Stone management

Edmond

Workup

• Imaging

• Renal fxn scan

• Metabolic workup: Bld & Urine

• Txn of metabolic stone

Review of modality of stone txn

• ESWL

• URSL

• PCNL

• Lap/open renal stone surgery

• Lap/open ureteric stone surgery

• Dissolution therapy

Treatment of Renal stone

• Staghorn stone• Upper and mid pole stone Lower pole stone• Renal pelvis stone with upper ureter extension• Calyceal stone• Horsehoe kidney stone• Pelvic kidney stone• Bilateral renal stone• Stone with PUJO

Treatment of ureteric stone

• Mx of renal colic

• Relief obstruction

• Ureteric stone: upper , mid , lower

• MET

• Bilateral ureteric stone

Epidmiology Epidmiology

• Epidemiology Caucasian of renal stone – 10%, rising trend• Recurrence of renal stone within 1 year – 10%• Recurrence of renal stone within 10 years – 50%• Calcium stone - 75% : Ca oxalate , Ca phosphate• Non-calcium stone – 25%

– Infection stone• Magnesium ammonium phosphate (10%)• Carbonate apatite• Ammonium urate

– Ammonium urate stones form when a urease-producing infection occurs in patients with urine that is supersaturated with uric acid/urate

– Uric acid (10%) : 20% of gout have uric acid stone– Rare stone that is radiolucent : Indinavir (HIV med), triamterene (K spari

ng diuretic) – Cystine stone (renal tubular defect – 1%)

Risk factorsRisk factors

Why does the stone form?

• Imbalance between stone promoter and inhibitor– Saturation below solubility product stone will not form– Saturation above solubility product crystal growth can be

prevented by increased inhibitors– Saturation above formation product stone forms despite

inhibitors

• Urine concentration btw solubility product & formation product metastable

• Urine concentration above formation product supersaturated

• Inhibitor of crystallization : Mg , GAG, Tamm-Horsfall (?) protein, citrate

• Phases of stone formation: – Nucleation: crystal nuclei occur on surface of

epithelial cell or on other crystal– Aggregation : Crystal nuclei form into clumps

Risk factors• Age (younger age group, peak at 40)• Sex (male)• Strong family history of stone formation• Race (Caucasian > black > Asian)• Positive family history• Diet: obesity

– High animal protein (high ca, uric & oxalate, low pH, low citrate)– High salt (hypercalciuria)– High Calcium intake is protective– Vit D (increase instestinal Ca absorption) – Vit C (cause hyperoxaluria)

• Occupation: sedentary lifestyle• Gout• Low fluid intake (urine output <1L)

Age

Gender

Season/climate

Fluid Intake

Stress/diet

Occupation

Mobility

Metabolic disorders

Genetic disorders

Anatomical abnormality

Family history

Risk Factors for Calcium Stone-Formation

Urinary Risk Factors for Stone-Formation

• Low urine volume (<1L/24hrs)

• Alteration in urinary pH (<5.5,>7.5)

• Hypercalciuria (>4mg/kg/24hrs)

• Hyperoxaluria (40mg/24hrs)

• Hyperuricosuria (>600mg/24hrs)

• Hypocitraturia (<250mg/24hrs)

• Hypomagnesiuria (<50mg/24hrs)

What are the risk factors for What are the risk factors for recurrent stone formation?recurrent stone formation?

• Diseases associated with stone formation – Hyperparathyroidism – Renal tubular acidosis (partial/complete) – Cystinuria – Primary hyperoxaluria – Jejuno-ileal bypass – Crohn’s disease – Intestinal resection – Malabsorptive conditions – Sarcoidosis

What are the risk factors for recurrent stone formation?

• Anatomical abnormalities associated with stone formation – Tubular ectasia (medullary sponge kidney) – Horseshoe kidney– Caliceal diverticulum, caliceal cyst – Pelvo-ureteral junction obstruction – Ureteral stricture– Vesico-ureteral reflux– Ureterocele

What are the risk factors for recurrent stone formation?

• Medication associated with stone formation – Calcium supplements (Normal adult - 20-50 mmol per

day)– Vitamin D supplements – Ascorbic acid in megadoses (> 4 g/day) – Triamterene – Indinavir– (acetazolamide)– (Sulphonamides) – Corticosteroid (increase enteric absorption of Ca)– Chemotherapeutic agent (uric acid)

What are the What are the Other Other risk factors forisk factors for recurrent stone formation?r recurrent stone formation?

• Onset of urolithiasis early in life ( i.e. below 25 years of age)

• Stones containing brushite (calcium phosphate

ImagingImaging

What is the diagnostic imaging What is the diagnostic imaging of choice for renal colic?of choice for renal colic?

• IVU has been the gold standard in the past– Bowel preparation and 6-hour fasting – KUB (preliminary film)– Immediate nephrogram (1mg/kg Omnipaque) – 5 mins > tomograms > – 10 mins (compression and release in prone position) > – 20 mins film– Post-micturition > delay film– Laterally visualized calyces on IVU not correspond to posterior row of ca

lyces– Abdominal compression during IVU is not necessary for child under 2

• The specificity and sensitivity of unenhanced helical CT was found to be similar or superior to that obtained with IVU

What are the advantages and What are the advantages and disadvantages of IVU?disadvantages of IVU?

• Advantages– Road map for percutaneous procedure, clear calyceal / ureter an

atomy, better function information– For emergency on table IVU - use double strength contrast (2mg

/kg)– Less radiation(2.5mSv)– Specificity – 90%

• Disadvantages– contrast nephropathy, allergy to contrast (mortality 1/1 million)– Can only see 90% stone (miss radiolucent stone)– Time consuming– Low sensitivity (60%)

What are the signs of What are the signs of obstruction on IVU?obstruction on IVU?

• Cause delayed dense nephrogram

• Clubbing of calyces

• Dilated renal pelvis/ureter

• Hold up of contrast

• Normal IVU during pain cannot rule out ureteric obstruction as cause

What are the advantages and What are the advantages and disadvantages of NCCT?disadvantages of NCCT?

• Advantages– No contrast, – demonstration of radiolucent uric acid & xanthine ston

e– Show alternative diagnosis, relationship with extra ren

al organ– ~100% sensitivity and specificity

• Disadvantages– Higher radiation (5mSv)– Less clear calyceal anatomy– Less suited for follow-up after the treatment of radiopa

que stones– Cannot see indinavir stone

• Greenwell et al, British study

What are the signs of What are the signs of obstruction on CT?obstruction on CT?

• Hydronephrosis

• Increased renal size

• Perinephric or periureteric stranding

• Ureteric wall edema (rim sign)

How about KUB?

• NCCT should be the initial imaging examination for acute ureteric colic

• preliminary KUB X-ray is unjustified– All stones visible on scout also seen on KUB– Reduce radiation and cost

• KUB after +ve CT for Rx and F/U decisions– If stone visible on scout no need for KUB– If NOT visible on Scout Perform KUB X-ray

• ~ 1/3 will show a radio-dense stone

• KUB still is required in the planning of treatment for urolithiasis.

What are the advantages and What are the advantages and disadvantages of USG?disadvantages of USG?

• Advantages– No radiation/contrast , cheap, accessible, radiolucent

stone– Should be considered the first imaging test in children

with suspected urolithiasis– (In child, renal cortex appear bright on US)– Sensitivity – 80%, specificity – 95%

• Disadvantages– No road map, operator dependant, difficult or unable t

o visualize mid-distal ureter

What is the diagnostic imaging What is the diagnostic imaging of choice for renal colic?of choice for renal colic?

KUB combined with US. Extensive experience shows that in a large proportion of patients these methods are sufficient for the diagnosis of a ureteral stone

Sensitivity of KUB – 50%, specificity – 70%

What are the radiological What are the radiological feature of stones?feature of stones?

What are the important issues What are the important issues of IV contrast?of IV contrast?

• Classified into ionic vs non ionic and low/ high or iso-osmolar

• High osmolar - more nephrotoxic• The most commonly used contrast media are the nonio

nic low osmolar which are still hypertonic with an osmolarity of about 600 mosmol/l eg omnipaque

• The only iso-osmolar contrast in clinical use is the visipaque

• Contrast media have a half life of 1 hour in the body and by 12 hours 90% is excreted by the kidneys

What are the precautions for those at risk What are the precautions for those at risk

of contrast allergyof contrast allergy??• Asthma (6X for low osmolar, 10X for high osmol

ar)– Alternative Ix– Defer Ix if poor control– Standby emergency drugs box

• Always use low-molecular non-ionic contrast medium

• Give a corticosteroid (e.g. prednisolone, 30 mg) between 12 hours and 2 hours before the contrast medium is injected

What is the risk of metformin of cWhat is the risk of metformin of contrast injection?ontrast injection?

• Metformin which was exclusively excreted by kidney• Precipitate lactic acidosis ~1/10000 (serum lactic acid c

oncentration > 5 mmol/L) in case of contrast-induced anuria

• Lactic acidosis is associated with high mortality, particularly when renal function is reduced – Symptoms of lactic acidosis:

• Vomiting, somnolence, epigastric pain, anorexia, hyperpnoea, lethargy, diarrhoea and thirst

– Treatment: Diuresis ≥ 100 ml/h during 24 hours– Serum creatinine, lactic acid and blood pH should be

monitored +/- ICU/medical care

What are the precautions of thosWhat are the precautions of those taking metformin?e taking metformin?

• EAU guideline– Serum creatinine level should be measured in every patient with diabete

s being treated with metformin – Metformin and normal serum creatinine

• metformin stopped for 48 hours from the time of the radiological examination until the serum creatinine remains normal

– Metformin & Reduced renal function• metformin should be stopped 48 hours before administration of cont

rast medium • metformin may resume 48 hours after the examination provided that

serum creatinine remains at the pre-examination level– if contrast given to patient taking metformin

• metformin stopped immediately• hydration to ensure U/O 100ml/hr x 24 hours• monitor serum Cr, lactic acid and blood gas

What is contrast nephrotoxicitWhat is contrast nephrotoxicity?y?

• Increase of 25%, or at least 44 μmol/L for Cr in 3 days following IV contrast administration

• Reduced renal perfusion and toxic effect on tubular cells

• Direct nephrotoxic effect• Vasoconstriction of glomerular afferent arterioles

causes a reduced GFR and increased renal vascular resistance

What are the risk factors of What are the risk factors of contrast nephropathy?contrast nephropathy?

1. Increased serum creatinine

2. Dehydration

3. Age over 70 years

4. Diabetes

5. Congestive heart failure

6. Nephrotoxic drugs, (NSAIDs, aminoglycosides)

7. Multiple myeloma

8. Injection of contrast medium at intervals less than 48 hours

When Contrast medium should not When Contrast medium should not be given, or should be avoided? be given, or should be avoided?

How to treat anaphylactoid reaction (not How to treat anaphylactoid reaction (not mediated by antibody) after IVU?mediated by antibody) after IVU?

• ABC• Intubated if necessary• 100% O2 mask• BP/P monitoring• Two large bore iv drip• Adrenaline 0.5mg (1:1000 – 0.5ml) intramuscularly,

repeat again every 5 minutes depending on pulse and blood pressure

• Piriton 10mg• Hydrocortisone 200mg• ICU care

What is the role of DMSA?What is the role of DMSA?

• 99mTC dimercaptosuccinic acid

• Cortical imaging

• Split renal function before planning definitive treatment

• Actively extracted by functioning renal tubules

How to prevent radiation How to prevent radiation hazards?hazards?

• Main slogan : ALARA as low as reasonably achievable• ( I ) Minimize scattering

– ( 1 ) Put the fluoroscopy beam under the table ( image intensifier is placed superiorly ) to minimize XR leakage and scattering.

– ( 2 ) Keep the image receiver as close to the patient as possible :• Decrease the distance between the focal spot and the receiv

er• Decrease the fluoroscopic beam intensity• Decrease blurring of the image• Serve as a scatter barrier

• ( II ) Decrease fluoroscopy exposure – ( 1 ) Decrease fluoroscopy time– ( 2 ) Use of last image – hold feature– ( 3 ) Collimation

• narrow the beam and limit the imaging area to the exact position of interest

How to prevent radiation How to prevent radiation hazards?hazards?

• ( III ) Distance protection ( inverse square law )

• ( IV ) Shielding– Lead apron 0.5 mm thick– Thyroid shield– Lead glove

• ( V ) Dosage monitoring by wearing dorsimeter

Specific Stone type & underlying factors

Calcium Oxalate (85%)• Hypercalciuria: 50%

– Definition: >7mmol Ca/day (men) , > 6mmol Ca/day (women) 1. Absorptive: increase intestinal absorption2. Renal: renal leakage of calcium3. Resorptive: increase bone demineralization (hyper PTH)

• Hypercalcaemia: – Primary hyper PTH (1% form stone)

• Hyperoxaluria: 1. Absorptive (enteric hyperoxaluria): short bowel syndrome colon exp

ose to more bile salts increase permeability of oxalate2. Renal: renal leakage of oxalate3. Primary hyperoxaluria: increase hepatic oxalate production

• Hypocitraturia: – Citrate forms soluble complex with calcium , prevent binding to oxalate

• Hyperuricosuria: – High uric acid uric acid stone Ca oxalate form stone on its surface

Uric acid (5%)• Human not able to convert uric acid to allantoin (very sol

uble)• Thus urine is supersaturate with insoluble uric acid• Uric acid exits as 2 form in urine:

– Uric acid : insoluble– Sodium urate: 20x more soluble in alkaline pH

• Human urine is acidic (metabolic product are acid) • Thus low urine pH predispose to uric acid stone formatio

n• 20% pt with gout have uric acid stone• 20% with uric acid stone have gout• 1% per year risk of stone formation after first gout attack• Myeloproliferative disease:

– Txn with cytotoxic drug cell necrosis large amount of nucleic acid convert to uric acid plug in collective system

• Txn: Alkalinization of urine

Ca phosphate (10%)

• Occur in patient with Renal tubular acidosis (RTA)• Defect of renal H+ secretion urine alkaline + metaboli

c acidosis• High urine pH increase supersaturation of Ca and Pho

sphate• Type 1 RTA (distal) :

– Failure of distal renal tubule to acidified urine– 70% type RTA form stone– Urine pH >5.5 , low citrate , hypercalciuria– Bld: metabolic acidosis, hypo K

• If urine pH > 5.5: use ammonium chloride loading test – If urine pH remain > 5.5 incomplete distal RTA

• Txn: acidified urine

Struvite stone

• Magenesium , ammonium & phosphates• Urease-producing bacteria which convert• Urea Ammonium + CO2• Alkalinized urine• Txn: acidified urine• Urease producing bacteria:

1. Proteus2. Klebsiella3. Serratia4. Pseudomonas5. Providencia6. Staphylococcus, ureaplasma urealyticum

Cystine stone• Autosomal-recessive• Disorder of transmembrance cystine transport• amino acids cystine, ornithine, lysine, and arginine, (“COLA”)• Result in decrease absorption of cystine from intestine and proximal

tubule of the kidney• About 3% of adult stone formers are cystinuric and 6% of stone-for

ming children• Cystine stones are relatively radiodense because they contain sulfur

atoms• Cystinuria urine supersaturate with cystine• Cystine is poorly soluble in acid urine• Dx: Cyanide-nitroprusside colorimetric test (cystine spot test) if +

ve 24 hour urine collection• 24hr cystine >250mg cystinuria • Txn: alkalinization of urine

Xanthine stone• Rare• Like other purine stones they are radiolucent and can be

confused for uric acid stones• Xanthine oxidase deficiency is autosomal recessive • Half of the homozygotes are asymptomatic

– Only biochemical evidence of lower serum uric acid levels and high urinary excretion of xanthine

• Xanthine oxidase converts hypoxanthine to xanthine and then to uric acid

• Allopurinol inhibits xanthine oxidase and in high doses it can precipitate xanthine stones (eg treatment of Lesch Nyhan syndrome)

• Xanthine is less soluble than hypoxanthine and hence the latter does not tend to precipitate

Analysis of stone Analysis of stone compositioncomposition

What are the methods of analysis of stone composition?

• Polarizing microscopy

• X-ray crystallography

• Infrared spectroscopy– All patients should have at least one stone ana

lysed– Repeated analysis when any changes in urine

composition, as a result of medical treatment, dietary habits, environment or diseases, might have influenced stone composition

Analyses in Analyses in uncomplicated stone uncomplicated stone

diseasedisease

What is diagnostic evaluation for What is diagnostic evaluation for single stone formers?single stone formers?

• History, P/E• Medications• Fluid intake• Biochemical screen

– U&E, Ca,PO4, uric acid, bicarbonate• PTH if Ca is elevated• Urine

– C/ST – PH>7.5 Infected stones– PH<5.5 Uric acid– Sediment for crystalluria– Urine culture –urea splitting organisms– Cystine test

• Xray• Stone analysis

Biochemical Investigation

• A bottle with HCL solution is used to measure calcium oxalate, phosphate, citrate and Mg

• A plain bottle is used to estimate uric acid• TWO 24-hor urine collections for each set of

analyses recommend• Collecting bottles:

– 5% Thymol in isopropanol (10ml for a 2-L blt) or– Stored at < 8 degree

• Fasting morning spot urine sample should be analysed

• A spot urine sample can provide a rough guide to the need of further analyses

Analyses in Analyses in complicated stone complicated stone

diseasedisease

Indications for metabolic stone Indications for metabolic stone evaluationevaluation

• Recurrent stone formers• Strong family history of stones• Intestinal disease (chronic diarrhea)• Pathologic skeletal #, osteoporosis• History of UTI with calculi• Gout• Solitary kidney• Anatomical abnormalities• Renal insufficiency• Stones composed of cystine, uric acid or struvite

Evaluation of stone formers 1Evaluation of stone formers 1

• History– Underlying predisposing conditions– Medications (Ca, Vit C, Vit D, steroids)– Fluid intake, meat consumption

Evaluation of stone formers 2Evaluation of stone formers 2

• Blood screen– Sodium, potassium, Calcium, uric acid– Creatinine– Parathyroid hormone

• Urine analysis– pH (>7.5 infection, <5.5 uric acid)– Culture– Microscopy for crystals– 24 hr urine: Ca, oxalate, uric acid, citrate, pH, cystine, total

volume– MSU : rule out infection

• Stone analysis

What are the summary of analyses in patients with uncomplicated and

complicated stone disease?

Patients should be advised to discard the first void urine sample and start collecting urine from there on including the first voided urine sample of the following morning

Hypercalciuria: >200mg/dayHypercalciuria: >200mg/day

• Absorptive: ↑intestinal absorption decreased PTH normal serum calcium– Type I – not responded to Ca restriction– Type II – responded to Ca restriction

• Renal (also known as renal leak)- High urinary Ca increased PTH normal serum calciu

m• Resorptive:

1. hyperPTH: excessive PTH excessive bone resorption increase renal synthesis of Vit D increase intestinal absorption of Ca hypercalcemia

2. Malignancy associated hypercalcemia3. Glucortocoid induced hypercalciuria

Hyperoxaluria (urinary oxalate > Hyperoxaluria (urinary oxalate > 40mg/day)40mg/day)

• Increased urinary saturation Calcium oxalate

• Causes– Primary (deficiency liver enzyme > early renal

failure > renal and liver transplant)– Enteric (chronic diarrhoea with fat malabsopti

on increase oxalate reabsorption, eg Bowel resection, IBD )

– Dietary: chocolate, spinach, nuts, strawberry, tea and ascorbic acid

Hypocitraturia (<250mg/day)Hypocitraturia (<250mg/day)• Citrate is an important inhibitor that can reduce Ca stone

formation– Metabolic acidosis reduces urinary citrate levels (due

to enhanced renal tubular reabsorption and reduced synthesis of citrate)

– Renal tubular acidosis, chronic diarrhoeal states (cause intestinal alkali loss), excessive animal protein, thiazide diuretics (hypoK and intracellular acidosis)

– RCT showed K citrate supplement in hypocitraturia Caoxalate stone remission rate 70% VS 20% in placebo

• Contraindicated in active peptic ulcer disease / hyperkalemia / Cr > 2.5mg/dl

Low Urine pH (<5.5)Low Urine pH (<5.5)

– Risk factor for both uric acid and Ca oxalate stone

– Undissociated form of uric acid serve as nidus for calcium oxalate stones through heterologous nucleaton

– Acidosis increases bone resorption and produces renal calcium leak

Hyperuricosuria (urinary uric aciHyperuricosuria (urinary uric acid >600mg/day)d >600mg/day)

– Uric acid reduces effectiveness of urinary inhibitors of crystallization promote Ca oxalate formation

– Increased dietary purine intake, gout, myeloproliferative and lymphoproliferative disorder, multiple myeloma, hemolytic disorders and increased insulin (decreased urine pH)

Uric acid stoneUric acid stone

• 3 main determinants – Low pH– Low urine volume– Hyperuricosuria

Uric acid stoneUric acid stone

• Low urine pH– Most important factor (most patients have nor

mal uric acid level but invariably have low urine pH)

– at pH 5, even modest amount of uric acid exceed solubility

– Low pH increases concentration of sparingly soluble undissociated uric acid direct precipitation of uric acid

What is cystinuria?What is cystinuria?• Autosomal recessive • Type A (chromosome 2), Type B (chromosome 19) type AB • Associated with defective renal absorption of cystine, ornithine, lysin

e , arginine (COLA), only cystine insoluble• 1% of all renal stones • The incidence of homozygous cystinuria is 1/20,000 and heterozygo

us 1/20 to 1/200• Median age of 20-30• The 24 hour urine excretion of normal cystine is <80mg• In homozygous cystinurics that quantity is >600 mg/day, heterozygo

tes > 400mg/day • Cystine stones commonly form in homozygous cystinurics but heter

ozygous cystinurics can form renal stones which may well not be cystine stones

• Cystione stones >4mm will normally be radioopaque due to their disulphide bonds

• Ground-glass appearance and hexagonal crystal in microscopy

What is Brand’s test?What is Brand’s test?

• Qualitative test for detecting cystine in urine >75mg/l

• Spot test for cystinuria • 12 drops of Na cyanide are added to the urine s

ample to stain the urine pinkly• Cyanide converts cystine to cysteine which

binds nitroprusside causing purple• False positive results may occur in homocystinur

ia or acetonurina, sulpha drugs, ampicillin or N-acetylcysteine

What is the treatment for cystiWhat is the treatment for cystine stone?ne stone?

• Diet: low in methionine, Na < 2g/day• Drinking: 24 hour urine > 3L• Drug:

– Potassium Citrate: 20-25 mmol/day TDS– Complex formation by chelating agents: – Thiol compounds: Vit B6 50mg QD together

• D-penicillamine (1-2g/day)• Alfa- mercaptopropionyl glycine (tiopronin) 750mg/day)

– Captopril : 75-100mg QD

• Accompanied by pyridoxine to avoid vitamin B6 deficiency

• Regular urine protein to detect nephrotic syndrome caused by penicillamine or mercaptopropionyl glycine

What is the medical treatment for cystine stone?

Renal tubular Renal tubular acidosisacidosis

Child presents with stunted growth• What is the diagnosis? (1)• What is the physiological abnormality in this child? (1)• Name the metabolic abnormality (1)• What is the usual urine pH? (1)• What is the usual component of stone formation? (1)

Q59

• KUB : bilateral medullary nephrocalcinosis• Dx : RTA type 1 (1)• Inability to excrete acid from collecting duct d

espite metabolic acidosis (1)• Hypokalemic, hyperchloremic, non—anion g

ap metabolic acidosis (1)• Elevated urine pH (>6.0), hypercalciuria, hyp

ocitraturia (1)• Calcium phosphate (1)

Renal Tubular AcidosisRenal Tubular Acidosis• Syndromes of metabolic acidosis resulting from defects in tubular hydrogen secretion

and urinary acidification• RTA I –

– The most common form of RTA– Thee majority of patients are females (80%) and 70% of them will form stones– Failure of H+ secretion in the distal nephron– Metabolic acidosis promotes bone demineralisation : secondary hyperparathyroid

ism, hypercalciuria hypocitraturia, coupled with high urine pH => calcium phosphate stones

– Usually occurs in adults : typical bilateral medullary nephrolithiasis– Children : vomiting, failure to thrive, growth retardation– Primary : idiopathic, hereditary (autosomal dominant or autosomal recessive), sp

oradic– Secondary : autoimmune diseaese, Sjogren’s syndrome, SLE– Tx: Sodium bicarbonate

Potassium citrate

• RTA II - – Due to Failure of bicarbonate reabsorption in the proximal tubule– Associated with generalised defect in proximal tubule function eg.

reabsorption of phosphate, urate– Associated with other absorptive deficiencies (Fanconi’s syndro

me)– Do not tend to form stones due to increase urinary citrate. – Metabolic acidosis leads to growth retardation and hypokalemia

• RTA IV – – Impairment of cation exchange in the distal tubule, reduced secr

etion of H+ and K+. – The unique feature is hyperkalemia– Associated with underlying aldosterone deficiency or resistance– Clinically associated with chronic renal damage such as diabetic

nephropathy / interstitial renal disease– Renal stone formation uncommon as excreted substrates eg. Ca

and urate decreased due to impaired GFR

What are some parameters to raise What are some parameters to raise

suspicious of renal tubular acidosis ?suspicious of renal tubular acidosis ? • Hypokalaemia hyperchloremic metabolic acidosis, incre

ased urine K and Na, hypocitraturia, hypercalciuria from resorption of bone, hyperphosphaturia

• Calcium phosphate stone• If pH above 5.8 in fasting morning urine = complete RTA• If urine pH is >5.8, confirmed by the ammonium chloride

loading test (oral 0.1g/kg = acid load). Urine pH that remains above 5.8 after an oral dose of ammonium chloride = incomplete RTA

(What are the analytical findings in patients with complete or incomplete

distal renal tubular acidosis?)

ESWL

4 factors of ESWL

• Energy source• Coupling

– System to transmit shockwave to decrease energy loss

• Focusing– Acoustic lens– Cylindrical reflector

• Imaging– USG, fluoroscopy or both

Generator type

• Electrohydraulic lithotripsy (EHL)– Spark is produced between two electrodes under water, which r

esults in the rapid expansion and collapse of a gas bubble and subsequent energy transmission

– A metal hemi-ellipsoid reflector is used to focus the energy– Result in great shot-to-shot variability as electrode wear down

• Electromagnetic lithotripsy– Cylindrical electromagnetic source, and energy is focused by an

acoustic lens• Piezoelectric lithotripsy

– Piezoelectric materials consist of ceramic or crystal elements (barium titanate) that produce an electrical discharge under stress or tension, or can be induced to rapidly expand by the application of a high-voltage pulse.

– The piezoelectric elements are placed on the inside of a spherical dish to permit convergence of the shock front

• For EM & PE acoustic output instability may occur

1. Electrohydraulic

2. Electromagnetic

3. Piezoelectric

Shock wave• What is shock wave?• A short-duration (<10us) aco

ustic pressure wave consist of a compressive phase & a tensile phase

• Compressive phase: initial short and steep compressive front with peak pressures of about 40 MPa (megapascals)

• Tensile phase: longer, lower amplitude negative (tensile) pressure of 10 MPa,

• Note that the ratio of the positive to negative peak pressures is approximately 5

Newer generator

• Higher peak pressure (more effective?)• Small focal zones (less painful)• Ideal for txn of ureteral stone• No observe improvement in SFR

• F1: electrode (focus of an ellipsoid)

• F2: target (kidney stone)

Dual Heads

• SW generated simultaneously from 2 reflectors through 2 axes in non-opposinig directions to the same F2

• Intensifies and localizes cavitational effects

• Better quality and rate of stone disintegration

Electroconductive

4th generation

• Electrode surround by highly conductive solution

• Shock generation by discharge between anode and cathode

• Repeatable spark location due to shorter interelectrode distance and reduced electrode wear (vs EHL)

• Electrode life time > 40000 impulses

• spark generation exactly at F2

Electroconductive

• Efficacy of the lithotripter

• Latest-generation lithotripters are at least as effective as the first lithotripters, but are much cheaper and have greater versatility

• 4th generation: Sonolith– Electroconductive– Large focal diameter of the SW (12.8–25 mm)

– A longer pulse duration (138–279 ns)– A relatively lower peak pressure– Achieved a high success rate, comparable with that us

ing the HM-3 machine but with lower analgesia requirements and very low re-treatment rates

ECL vs EHL

• Reduction in shockwave pressure variability

• Improved energy transfer to the stone

• Linear relation between the voltage setting and the pressure at F2 stone Fragmentation

• Result Tolley–Sonolith between 2004 and 2006

–plain KUB and USG at 1 and 3 months

–SFR: – 77% (<10mm), 69% (11-20mm), 50% (>20mm)

– 74% (lower), 70% (upper), 78.5 (middle), 74% (renal pelvis)

Mechanism of stone comminutionMechanism of stone comminution• Stone communition is a progressive process consisting:

– Initial (base of dynamic squeezing) propagation– And colaescence (because of increasing fragility) – Mechanical stress produce micro-cracks sudden break off of the calculus

• Spallation (剝落 )– Once the shockwave enters the stone, it will be reflected at sites of impe

dance mismatch. One such location is at the distal surface of the stone at the stone-fluid (urine) interface

– As the shockwave is reflected, it is inverted in phase to a tensile (negative) wave. If the tensile wave exceeds the tensile strength of the stone, there is an induction of nucleation and growth of microcracks that eventually coalesce, resulting in stone fragmentation

• Cavitation (氣穴 )– During the negative pressure wave, the pressure inside the bubble falls

below the vapor pressure of the fluid, and the bubble fills with vapor and grows rapidly in size (almost three orders of magnitude). As these bubbles grow, they oscillate in size for about 200 μs and then collapse violently, giving rise to high pressures and temperatures. In the absence of any boundaries, a cavitation bubble remains spherical during collapse, releasing energy primarily by sound radiation, the majority of which is in the form of a shockwave

• Circumferential compression (壓縮 )– The shockwave inside the stone advances faster through the sto

ne than the shockwave propagating in the fluid outside of the stone. The shockwave that propagates in the fluid outside of the stone thus produces a circumferential force on the stone

• Tear & Shearing (撕破 )– In contrast to compression waves, which move the molecules in

the direction of propagation, a shear wave results in translation of molecules transverse to the direction of propagation, and therefore the molecules are not compressed but are shifted sideways by the wave

• Dynamic squeezing: (擠壓 )– Stone fragment by shear waves created inside the stone driven by sque

ezing wave from the lateral stone borders

– A model accounts for all acoustic phenomenon

What are the imaging systems during ESWL?

• Fluorosocopy– Advantages

• In-situ tx of ureteric stones• in all parts of ureter• Shorter learning curve

– Disadvantages• No direct targeting of radiolucent stones• Small stones sometimes are difficult to locate• Exposure to radiation

• USG– Advantages

• Easy targeting of radiolucent stones and smaller renal stones• Real-time imaging without excessive radiation exposure

– Disadvantages• Is-situ treatment of ureteric stones is possibly only for prox and dista

l ureter• Longer learning curve

Factor influence efficacy

• 1. Focal zone: – Diameter at which the peak pressure is half of

P+, known as -6dB– Energy focused on stone depends on source

and method of focusing– But focal zone has little relevance in the disint

egrative efficacy– Usually: larger FZ renal stone, small FZ

ureteric stone– In short : larger FZ increase efficiency

• 2. Pulse rate frequency: – Cavitation bubbles produced by the rarefactio

n phase of the SW can decrease the energy of the following impulse thru scattering and absorption

– Longer pulse frequency less bubble in the path to decrease the energy

– Only the –ve phase is affected– Increase PRF from 1Hz to 1.8Hz has drastic e

ffect on SW energy

• 3. Coupling– HM3 use water bath now coupling

cushions– More air pockets less SW efficacy– Gel: use bubble-free USG gel– Lower viscosity gel better– Greater quantity of gel– Apply gel from stock container as a large

amount rather than hand or zigzag application from squeezed bottles

• 4. Localization & monitoring:– Compression belt to reduce resp movement– Larger FZ to reduce impulse miss the stone– Real time coaxial USG localization – Automated fluoroscopic localization

• 5. Impact on pulse rate: – Reduce pulse from 2Hz to 1Hz increase stone passag

e rate from 20% 80%– RCT: 1Hz has better outcome vs 2Hz esp with stone

> 10mm (60% vs30%),

• 6. Ramping: – Slow increase of generator voltage – Less pain– Pretreatment at lower voltage reduce renal trauma

by vasoconstriction• 7. SW energy:

– Stone fragmentation is achieved as long as the threshold is exceed

– Base of effective energy dose (Eeff at intensity level x impulses)

– Renal stone: Edose (12mm)= 100-130– Ureteral stone: Edose (12mm) = 150-200

Contraindications Absolute1. Pregnancy 2. Uncorrected bleeding disorder 3. Uncorrected hypertension4. Untreated infection5. Body habitus (obesity or severe skeletal

malformations) Relative

1. Aneurysm2. Pacemaker3. Downstream obstruction (e.g PUJ stone)4. Excessive stone burden

What is the important point for Steinstrasse?

• Internal ureteral stents are now commonly inserted before ESWL for large renal stones, the frequency of Steinstrasse has decreased

• Steinstrasse: Accumulation of gravel that does not pass within a reasonable period of time , and interferes with the passage of urine

• PCN results in passage of fragments• URS: help remove the leading stone in distal ure

ter

Factors predicting usefulness• Stone free rate (EAU 2010)

– <1cm – 80%– 1-2 cm – 60%– >2cm – 50%

• Stone factors– Size– Site– Composition as measure by HU on CT scan (> 1000)– Calyceal anatomy

• Patient factors– Age: for renal stone, age stone free rate– BMI– Stone skin distance– Pain control

size• EAU 2010

– >20mm consider PCNL although ESWL still an option– > 40 x 30mm combine PCNL and ESWL 71%-96% su

ccess (sandwich procedure)• But single kidney can still try ESWL• ESWL after PCNL better then vice versa

106

< 20mm > 20mm

Dornier HM3 75-89% 39-63 %

Newer model 45-60% 45-60%

Stone Burden

• Can be expressed in different way– Largest diameter: length of stone on KUB– Stone surface area (SA): Length, width

– Stone volume (SV): CT

Composition

• Stone resistant to ESWL in descending order :– Cystine– Bushite– Ca oxalate monohydrate– Hydroxyapatite– Struvite– Ca oxalate dihydrate– Uric acid

• Matrix stone, soft stone composed of up to 65% organic matter, compared to 3 – 4 % of most noninfected stones, is associated with poor outcome with ESWL, and PCNL is preferred

Hard stone

• Hard stone like cystine and brushite should be treated with ESWL only when they are < 15 mm in size.

• RIRS may be beneficial in cystine stone, because life-time risk of recurrence, therefore less renal trauma and less morbidity.

• EAU 2010 : cystine stone– < 15mm ESWL 71% SFR– > 20mm ESWL 40% SFR

What is the importance of shape & CT HU unit to determining successful rate of ESWL to cyst

ine stone?• Rough-appearing external surface on plain film i

maging were more apt to be fragmented with shock-wave energy than those with a smooth contour

• Computed tomography attenuation coefficients of the latter were significantly higher in smooth-type stones

• HU > 1000 asso with reduce stone disintegration 50% vs 100% if HU < 500 [Joseph JU2002]

• Stones with higher attenuation values have also been demonstrated to be resistant to shock-wave fragmentation

When is stenting required in ESWL?

• Indication: – Obstructed infected system– New-onset of renal failure– Stone > 2cm : steinestrasse after ESWL 10%

(vs 1% if < 2cm)

• Improve passage of stone

• Prevent obstruction

• Prevent loss of ureteral contraction

Stent with ESWL useful?

• Stent + ESWL for proximal ureteral stone does not affect stone fragmentation or clearance, but associated with more symptom (Grade 1B)

• Recommendation against stenting for proximal ureteric stone

• Routine Ureteric stents compromise stone clearance after shockwave lithotripsy for ureteric stone [Tolly BJUI 2008]

Prophylactic antibiotic• Antibiotic prophylaxis in pt with sterile urine before

txn reduce risk of UTI (2% vs 6% in placebo) [MA ,Pearle Ju1997]

• Expert panel from AUA [JU2003]– Not indicated for most of the urology patients– Not indicated for pin, plate or screw

• Advised for patient who had increased risk of hematogenous joint infection (Total joint replacement)– For total joint replacement within 2 years– Immunocomprimised patient– Co-morbidity

• Previous joint infection• Malnourished• HIV infection, DM, malignancy

Pain

• Related to energy density of SW as it passes through skin, size of focal point

• short acting parenteral sedative narcotics: alfentanil, midazolam, propofol

• topical agents: EMLA cream (mixture of lidocaine and prilocaine) ， 45 mins before SWL

• Pain control is important to reduce patient movement causing mistargeting

• Prefer: Oral + IV PRN (Alfentanil) [Ng 2009]• those who receive GA experienced a significantly greater

stone free rate than IV sedation• ( Due to more controlled respiratory excursion)

Evidence of pre-treatment SW• Willis (2006) reported a practical way to protect the treated kidne

y from clinical dose of shockwaves. • Before the administration of a clinical dose of 2000 shocks at 2

4 kV with an unmodified HM3 lithotripter• A pretreatment dose of 100 to 500 shockwaves at 12 kV is admi

nistered, followed by the full clinical dose to the same site.• Under these conditions, the normal lesion of approximately 6%

is reduced to approximately 0.3%, a highly significant change • One hypothesis of a possible mechanism of this outcome

– Pre-dose of shockwaves induces vasoconstrictive event that prevents an incoming stress from shearing the vessel wall

– Or prevents or reduces the number of cavitation events.• A reduction in cavitation potentially protects the parenchyma from c

avitation-induced injury. A clinical trial is needed to test this result in patients

• Occur when the treatment is apply to same or opposite pole (give 100 shock for pretreatment)

ESWL best practice (EAU)

• Best Txn of patient who desire txn with minimal anaesthesia• Renal stone <2cm, ESWL first choice• Lower SFR & more number of session need if stone> 1cm• Ureteral stent should be inserted in case renal stone >2cm• However , stenting should not be use for proximal ureteric stone

dose not affect stone fragmentation or clearance but asso with more symptoms

• Stones with medium density >1000HU upon NCCT are less likely to be disintegrated

• Obesity – poor localisation with imaging and increase skin to stone distance poor outcome

• Women of childbearing age: caution in txn of distal ureteric stone with ESWL possibility of damage to undertilised egg or ovaries

• NO asso of SWL with HT and DM

• Mid-ureteric stone – prone• Lower ureteric stone -Traditionally prone• Optimal frequency is 1Hz (safer and more effective, start

with low energy and stepwise power ramping)• Shock-wave frequency increases, tissue damage increas

es • Meta-analysis comparing 60 shocks/min vs 120

shocks/min– Patient treated with 60 shocks/min, significant

greater likelihood of a successful treatment• Escalating voltage may have protective effect against ES

WL damage and better stone clearance

• ESWL should be performed by urologist who was experience in ESWL

• The number of ESWL sessions : not exceed three to five• For more sessions, a percutaneous method • No rules on how frequently ESWL sessions can be repea

ted • Two successive sessions must be longer for electrohydr

aulic and electromagnetic lithotripsy than for treatments using piezoelectric equipment

• Careful and long fluoroscopy and USG time is essential• Decrease air pocket in coupling gel is essential – apply U

SG gel to water cushion straight from container rather than by hand

• Careful control of pain during treatment is necessary to limit pain-induced movements and excessive respiratory excursions

MET after SWL

• Meta-analysis BJUI 2009 Yefang Zhu : Tamsulosin – Improves clearance of fragments after ESWL by 20%– With ~1 week faster stone passage– Reduce pain medication requirement– Fewer returns to hospital– Steinstrass resolve completely vs 25% require intervention in

placebo gp– Work best esp in stone > 10 to 24mm

• K citrate for Ca Oxalate stone: – Improve SFR

• MET vs ESWL: – Equally effective in distal ureteric stone 4-7.9mm– MET less effective in stone 8-9.9mm

Conclusion

• MET is recommended (both nifedipine and tamsulosin) in facilitating clearance of fragments after ESWL of ureteral stone and to reduce pain medication requirement

Complications after ESWL?Complications after ESWL?

1. Pain2. Hematuria3. UTI and occasional sepsis4. Steinstrasse complicates (1-4%) 10% if > 2cm5. Perirenal hematoma (25% radiological) (<1% significant)6. Renal edema 7. Gastric or duodenal erosion commonest extra renal com

plication of ESWL8. Arrhythmia during ESWL session9. Chronic: Still some controversies

– HT– DM– Decrease RFT

Who are at risk of complication?

• Acute renal injury may be more likely to occur in patients

1. Pre-existing hypertension

2. Prolonged coagulation time

3. Coexisting coronary heart disease

4. Diabetes

5. Solitary kidneys

URSL

Indications• Stone factor:

1. ESWL failure 2. Lower pole stone3. Cystine stones4. Bilateral ureteric stone5. Stone in a calyceal diverticulum 6. Stenosis of a calyceal infundibulum or tight angle between renal pelvis and in

fundibulum. The flexible ureteroscope can negotiate acute angles and the laser can be used to divide obstructions.

• Patient factors: 1. Obesity such that PCNL access is technically difficult or impossible 2. Obesity such that ESWL is technically difficult or impossible. BMI >28 3. Musculoskeletal deformities such that stone access by PCNL or ESWL -e.g.kyp

hoscoliosis)4. Bleeding diathesis 5. Horseshoe or pelvic kidney

• ESWL only 50% success• PCNL difficult : bowel proximity and variable blood supply

6. Patient preference

Advantage of URSLAdvantage of URSL• Access to virtually the entire collecting system is possible• Holmium:YAG laser has a minimal effect on tissues at distances of 2–3 mm

from the laser tip and so collateral tissue damage is minimal • More effective treatment option than ESWL, with a lower morbidity than PC

NL• laser lithotripsy (reliable method for treating urinary calculi, regardless of har

dness)• It can also allow access to areas of the kidney where ESWL is less efficient

or where PCNL cannot reach• Safely used in pregnancy• Treatment of bilateral ureteral stone simultaneously• Small stones and fragments are best retrieved with a basket or a forceps • most suited to stones <2 cm in diameter• Renal stone: ESWL and PCNL are recommended primary txn options• Flexible URS: txn alternative for lower pole stone up to 20mm

Standard technique

Ho: YAG laser lithotripsy

• Regardless of hardness

• Ureteral stones: 365-um laser fibre

• Intracaliceal stone: 200-um fibre

• Better SFR at 3 months than EHL (97% vs 87%)

What are the advantages of What are the advantages of access sheath?access sheath?

• Ureteral access shealth: 9-16F• Operating time might be reduced for highe

r stone burdens where multiple ureter passages are necessary

• The maintenance of a low-pressure irrigation system by continuous outflow through the sheath

• follow-up series indicate a low rate of ureteric strictures

What is the advancement of baskets?

• Nitinol baskets preserve tip deflection of flexible ureterorenoscopes

• Tipless design reduces the risk of mucosa injury • Nitinol baskets are most suitable for use in flexib

le URS

• Nitinol baskets are more vulnerable than a stainless steel basket, and laser or EHL might break the wires of the basket

SFR

• Overall SFR: 81-94% • Appropriate for stone of any size in proximal

ureter: SFR 81%• Proximal stone: Flexible URS (87%) vs Semir

igid URS (77%)• < 2cm: >80%• > 2cm: 50%• Majority of pt stone free in single procedure,

10% require auxillary procedure

EAU GL 2010

RIRS result on Renal stone

• SFR for stone < 15mm : 50-80%

• Larger stone can also be treated successfully

• NOT recommended as 1st line for renal stone

• Flexible URS could become 1st line for lower pole stones < 15mm

• Simultaneous URS + PCNL: not routine

Stone extraction

• Intraureteral manipulations with stone basket should always be performed under direct URS vision

• Fluoroscopic imaging of the stone alone is not sufficient

• Obvious risk of injury to ureter

Consent:

Intraoperative complication• Bleeding (0.1%)• Ureteral injury (0.5%)• Ureteral avulsions (0.1%)• Stone migration (4%)

Early complication: • Fever or sepsis (1%)• Hematuria (2%)• Renal colic (2%)• Transient VUR (4%)

Late complication: • Ureteric stricture (0.5%)

Stenting• No improved fragmentation with stenting• Frequent LUTS related to stents• Routine stenting after uncomplicated URS not necessary• Complications: stent migration, UTI , breakage , encrustation a

nd obstruction• Increase expense, FC for removal• Strong recommendation against routine stenting after

uncomplicated URS (Grade 1B)• Clear indications:

1. Ureteral injury or perforation2. Larger residual stone burden 3. Stone fragments >2mm remain in ureter

4. Impacted stone with edematous ureter

5. Prolonged manipulation (esp upper 1/3)

6. Stricture7. Solitary kidney8. Renal insufficiency

PCNL

Indications

• For stone <20mm, ESWL has the advantage of lower morbidity

1. Stones >3 cm in diameter 2. Failed ESWL and/or an attempt at flexible URS

L 3. Staghorn calculi• ESWL and/or repeat PCNL being used for resid

ual stone fragments. • For stones 2–3 cm in diameter, PCNL gives the

best chance of complete stone clearance with a single procedure, but this is achieved at a higher risk of morbidity.

Prophylatic antibiotic?• Mariappan and associates (2005) have reported that

– the best predictor of post-PNL urosepsis is stone culture or renal pelvic urine culture results, rather than bladder urine culture results.

– The fragmentation of stones, despite sterile urine, may release preformed bacterial endotoxins and viable bacteria that place the patient at risk for septic complications

• Therefore, struvite stone pt or in whom infection is suspected should receive– minimum of 2 weeks of broad-spectrum antibiotics before surger

y to reduce the risk of sepsis.– Parenteral antibiotics should be administered preoperatively in a

ny patient in whom urinary infection is suspected.

• Patients with radiological evidence of struvite stone should be treated with oral antibiotic x 2 weeks even with sterile urine ( 35 % incidence of bacteruria after PCNL )

• Prophylactic antibiotic should be given to all cases ( reduce the incidence of post-op UTI from 12 % to 2 % , Tolly )

• Cephalosporin is the most suitable prophylactic antibiotic given in case of sterile urine because the most common secondarily infecting organism is Sta. Epidermidis

Procedure• Pre-procedural USG + fluoroscopy:

– Best access site and stone position– Ensure no organ within the planned path

• PCNL is the removal of a kidney stone via a track developed between the surface of the skin and the collecting system of the kidney

• General anesthesia is usual, though regional or even local anesthesia (with sedation) can be used

• Inflation of the renal collecting system (pelvis and calyces) with fluid or air instilled via a ureteric catheter inserted cystoscopically

• A posterior approach is most commonly used– below the 12th rib (to avoid the pleura and far enough away from the rib to avoid

the intercostals, vessels, and nerve)– through a posterior calyx, rather than into the renal pelvis, because this avoids da

mage to posterior branches of the renal artery that are closely associated with the renal pelvis.

• Percutaneous puncture of a renal calyx with a nephrostomy needle• Once the nephrostomy needle is in the calyx, a guide wire is inserted into th

e renal pelvis to act as a guide over which the track is dilated • An access sheath is passed down the track and into the calyx• Through this a nephroscope can be advanced into the kidney • An ultrasonic lithotripsy probe is used to fragment the stone and remove the

debris.

Calyceal Anatomy

• LAMP – lateral ant, medial post• Brodel configuration:

– posterior longer, more lateral (many “l”)– 69% Rt kidney is Brodel

• Hodson configuration :– posterior shorter, more medial (“s”, no “l”)– 79% Lt kidney is Hodson

• 99% superior calyceal group drain by 1 midline infundibulum

• 96% midzone drained by paired calyces arranged in 2 rows (anterior and posterior)

Puncture: Munver

Overall Cx Intrathoracic Cx

Infra - costal 5 %

Supra - costal 15 % ( 3 X )

Supra – 12th 10 % ( 2 X ) 1.5 %

Supra – 11th 35 % ( 7 X ) 23 %

Result

• For small stones, SFR 90–95%

• For staghorn stones, SFR of PCNL + postoperative ESWL for residual stone fragments : 80–85%

Result: upper pole puncture

• Tolley, Western General Hospital [BJUi 2007]• 66 PCNL with upper pole puncture• Overall SFR : 78%• Thoracic complication: 3%• Overall complication: 30%• Conclusion:

– Upper pole puncture asso with minimal morbidity– SFR depends on size of stone rather than puncture sit

e

What are some tricks of PCNL?• The puncture site on the skin lies in the extension of the l

ong axis of the target calix• The puncture avoids aiming at infundibulum• This is the safest access point because it uses the infund

ibulum as a conduit to the pelvis• Puncture pass thru papilla (no major blood vessels)• Staghorn stone: subcostal or supracostal upper pole

puncture• CT-guided renal access may be an option if failed fluoros

copic or US guided• Renal tract dilatation is possible using the Amplatz syste

m, or balloon dilators (no difference in morbidity, less operation time but more cost)

• Lower pole puncture at posterior calyx - Mid-pole stone will be left

Percutaneous antegrade access

• Indications: – Cases with large impacted upper ureteric ston

e (>15mm)– Combination with renal stone removal– Ureteral stones after urinary diversion– Failure of retrograde ureteral access to large,

impacted upper ureteral stones

• SFR: 85% and 100%

• Complication rate: low and acceptable

What is mini-perc?

• Smaller shaft calibres of 12-20 F

• Mini PCNLVS PCNL (prospective study by Li Ly)– Operation time was longer– Blood transfusion rates lower– No significant differences in trauma response

• As treatment time increases with stone size, this method is recommended only for stones with a diameter < 20 mm

• The value of mini-perc in adults has not been determined, but mini-perc is the method of choice for percutaneous stone removal in children

What are the pros and cons of What are the pros and cons of supine PCNL?supine PCNL?

• RCT showed no difference between supine and prone PCNL except less operation time in supine

Films taken after an urologic operation• What has happened? (2)• What is the incidence? (1)

Q23

• Colonic injury during PCNL• <1% of PCNL

• In uncomplicated cases, tubeless percutaneous nephrolithotomy, with or without tract fulguration, application of a sealant or double-J stenting, is a safe alternative (RCT showed less local pain / shorter hospital stay)

Tubless PCNL• Exclusion criteria included :

– operative time longer than 2 h, – three or more percutaneous accesses, – perforation of the collecting system, – bleeding, – significant residual stone burden. – Obstructed ureter

• All patients had antegrade stents placed after PNL • ( 6F stents for stone patients and 14/7F stents for endopyelotomy p

atients. )• Adv :

– shorter hospitalizations (1.25 days) – lack of external drainage tubes.

• Disadv :– wearing a urinary catheter for 24 h, – a second procedure is necessary for stent removal.

What are indication and contraindication of PCNL?

• Indication: – Stone > 3cm or staghorn st

one– Renal pelvis stone > 2cm– Lower pole stone > 1cm– Anatomical abnormaly : hor

seshoe kidney, calcyceal diverticular stone , obesity, kyphoscoliosis

– Failed ESWL or URSL– Foreign body

• Contraindication: • Absolute :

– Bleeding disorder– Proegnancy– Spesis– Poor kidney fxn (nephrecto

my) – Need of open procedure

• Relative: – Horseshoe or ectopic kidne

y (bowel injury)– Co-morbidities– Anterior calyceal divedrticul

um

What are the complication of PCNL?

• Access: – Bleeding (10%)– Require embolization (1%)– Require nephrectomy (rare) – Perforation of adj organ (bowel <1%, pneumothroax 0-5%) – Hydrothorax in supracostal puncture (15%)– Access failure (5%)

• Related to stone removal: – Infection (bacteriuria 70%, sepsis 1%)– TUR syndrome (rare) – Extravasation of irrigant (30%) – Renal pelvis injury – Residual stone (10%)

• Others: – Pleural effusion (10%)– Mortality (<1%)

• Major bleeding: – Termination of operation– Placement of nephrostomy tube– Secondary intervention at later date– Clamp nephrostomy tube to stop venous

bleed

• Persistent or late secondary bleeding– Artery injury– Angiographic super-selective embolisation– Nephrectomy is rare

Open/Lap renal stone surgery

Indications

1. Complex stone burden (projection of stone into multiple calyces, such that multiple PCNL tracks would be required to gain access)

2. Failure of endoscopic treatment 3. Anatomic abnormality that precludes endoscopic surger

y (e.g., retrorenal colon)4. Body habitus that precludes endoscopic surgery (e.g., g

ross obesity, kyphoscoliosis)5. Patient request for a single procedure where multiple P

CNLs might be required for stone clearance6. Nonfunctioning kidney (pain, recurrent urinary infection,

hematuria) esp with staghorn stone to reduce infective complication

Options

• Small to medium-sized stones– Pyelolithotomy – Radial nephrolithotomy

• Staghorn calculi– Anatrophic (avascular) nephrolithotomy - – Extended pyelolithotomy with radial nephrotomies (sm

all incisions over individual stones)– Excision of the kidney, bench surgery to remove the s

tones, and autotransplantation

Complications

• Wound infection (infection stones)• Flank hernia• Wound pain• Stone recurrence after open stone surgery • Scar tissue that develops around the kidney will

make subsequent open stone surgery technically more difficult.

• The superiority of open surgery over less invasive therapy, in terms of stone-free rates, is based on historical experience, but no comparative studies are available yet

Lap ureterolithotomy

• Retroperitoneal or transperitoneal access

• When other non-invasive procedure failed

• For both renal and ureteric stone

• Esp for stone in ventral caliceal diverticulum

• < 2% conversion rate

Medical dissolution therapy

Indication

Uric acid stone:• Uric acid stones form in concentrated, acid urine to de

crease acidity of urine• Hydration (urine output 2–3 L/day)• Urine alkalinization

– Aim urine pH 6.5–7 – sodium bicarbonate 650 mg TDS or – potassium citrate 30–60 mEq/day

• Allopurinol:– For those with uric acid secretion > 1200mg/day– Inhibits conversion of hypoxanthine and xanthine to uric acid– 300–600 mg/day

• Dietary manipulation (low purine diet)

Cystine stones• Most cystinuric patients excrete about 1 g of cystine per day• Cystine solubility in acid solutions is low (300 mg/L at pH 5, 400 mg/L at p

H 7)• Treatment:

– Reduce cystine excretion (dietary restriction of the cystine precursor amino acid methionine and also of sodium intake to <100 mg/day)

– Increase solubility of cystine by alkalinization of the urine to >pH 7.5, maintenance of a high fluid intake

– Drugs that convert cystine to more soluble compound– D-penicillamine, N-acetyl-D-penicillamine, & mercaptopropionylglycine – Bind to cystin the compounds so formed are more soluble– D-penicillamine (allergic reactions, nephrotic syndrome, pancytopenia, protein

uria, epidermolysis, thrombocytosis, hypogeusia)• Cystine stone are very hard• Flexible ureteroscopy (for small) and PCNL (for larger) cystine stones are

used where ESWL fragmentation has failed

Chemolytic dissolution

• Adjunct to ESWL, PCNL, URS, open Sx to achieve more complete elimination of small residual stone/fragments

• Staghorn stone: ESWL + dissolution as low invasive option

• 2 nephrostomy catheters – to irrigate renal collecting system– Prevent chemolytic fluid draining into bladder– Reduce risk of increased intrarenal pressure

• Large stone burden– JJ stent to protect ureter

Percutaneous chemolysisPercutaneous chemolysis

• Infection stone– 10% solution of Hemiacidrin (Renacidin), pH 3.5-

4, or– Suby’s G solution– Abx prophylaxis– One PCN in, another PCN out– Increase contact surface area with ESWL– Several week chemolysis + ESWL x complete sta

ghorn– Option of High risk pt– Risk: cardiac arrest due to hypermagnesaemia– Contraindicated in immediate postop stage

Percutaneous chemolysis• Brushite stone:

– Hemiacidrin/ Suby’s G solution, for residual fragments after other Tx

• Cystine stone– Soluble in alkaline – 0.3-0.6mol/L THAM (trihydroxymethyl aminomethan) solution (p

H 8.5-9), or – 200mg/L N-acetylcysteine

• Uric acid stone• THAM• Dissolve with bicarbonate treatment

• Ca Oxalate or ammonium urate stone– No useful Rx– Ca Oxalate in infection stone markedly reduce stone solubility in

Hemiacidin

Treatment

Natural history of renal stone

• 15% pass & 50% require intevention in 5yr [Glowacki 1992]

• Asymptomatic calyceal stone < 15mm: no difference SFR, QOL, RFT & admission [MRC, Keeley BJU2001]

• EAU 2010: Spontaneous stone passage rate• Renal stone

– < 4mm : Spontaneous pass 80%– 6-10mm : pass 10-53%– Stones > 5 mm - highly likely obstruction, drop in relative renal f

unction and require intervention

• Ureteric stone– Proximal 25%, mid 45%, distal 70%

WW ? For who• Traditional indications for intervention are pain, infection, and obstruction• Asymptomatic stones followed over a 3-year period are more likely to

require intervention (surgery or ESWL) or to increase in size or cause pain if they are >4 mm in diameter and if they are located in a middle or lower pole calyx

• Patient’s job

What are the indications for What are the indications for active stone removal? EAUactive stone removal? EAU

Renal stone: recommendations

• Method offering lower invasiveness or morbidity should be selected

• < 10mm ESWL

• 10-20mm ESWL as first line but PCNL is 1st line for LPS

• > 20mm PCNL is preferred

• Uric acid stone: oral chemolysis +/- disintegration

Staghorn stone

Staghorn stone

What is staghorn stone?• Definition: Stone with a central body and at least one cali

ceal branch• Partial staghorn: fills only part of collecting system• Complete staghorn: fills all calices and renal pelvisWhat is it compose of ?• Struvite stone (calcium, ammonium and magnsium phos

phate) • Urea spliting organsim (PKS PPS) • Urea ammonia (NH3) + bicarbonate• Ammonia(NH3) + H2O ammonium NH4 + OH

Staghorn stone

Why need to treat staghorn stone?• According to study by Blandy and Singh [JU1976]

– Staghorn stone cause symptom– If left with observation : 28% die of stone related renal failure– If treat with surgery: mortality is only 7%

• According to study by Teichman [JU1995]– NO patient with complete stone clearance die of renal –related di

sease vs 3% without clearance of fragments and 70% who refuse surgery

• ~30% of patients with staghorn calculi who did not undergo surgical removal died of renal-related causes—renal failure and urosepsis

• Thus treatment of staghorn stone is indicate

How should staghorn stone be treated?

For stone> 2cm• ESWL: No because SFR 40-60% at most• Flexible URS: no because SFR < 60%• PCNL : yes because highest SFR : >90%• Open surgery vs PCNL in complete staghorn stone [Egy

pt Gp (Al-Kohlany, JU2005]• Conclusion:

– PCNL approaching the SF of open• At discharge (49% vs 66%) and at FU (74% vs 82%)

– PCNL : lower morbidity, shorter operative time, shorter hospital stay and earlier return to work

– Stone-free rates for both groups at follow-up were approximately 80%

AUA GL – stone free rate

SFR Significant complication

Transfusion Procedure per patient

PCNL 78% 15% 18% 1.9

PCNL + SWL 66% 14% 17% 3.3

SWL 54% 19% Very low 3.6

Open surgery 71% 13% ~20-25% 1.4

MEDLINE search 1992 – 7/2003

Combine SFR lower because the last procedure is SWL in some series

Bilateral staghorn stone

• Manage symptomatic first, then good function side in bilateral staghorn disease – Determined by DMSA, best for the differential

function– Simultaneous bilateral PCNL is safe with adva

ntage of single anesthesia except large stone burden and complex pelvicalyceal system

Lower pole stone

Natural hx of LPS

• From 4 reportsoApproximate 10-20% asymptomatic

stones become symptomatic per year

oFor these, 50-60% eventually require surgical intervention

Lotan et al J Urol 2004 172 (6) p2275-81

Any benefit of treating it?

• MRC trail [F.X Keeley el at. BJUi 2001, 87, 1-8]

• Preliminary results of a randomiszed controlled trial of prophylactic SWL for small asymptomatic renal calyceal stones

• 228 patients randomised to ESWL vs control • All <15mm stone, > 70% LPS• ESWL Max 3 session• FU 2.2:

• SFR: ESWL 28% vs observe 17% (insignificant)– addition tx ( include analgesic/ antibiotic / JJ / URS ):

ESWL 15% vs observe 21% • Thus: ESWL will have an increase SFR & less additional

txn require

Is ESWL less effective in LPS?

• Overall SFR of LPS vs upper & mid PS – 60% vs 90%– Meta-analysis by Lingeman [JU1994]

• Stone size stratification – Up to 10mm: 75%– 11-20mm: 55%– Over 20mm: 30%

What determine the SFR of LPS?

• Lower pole collective system anatomy [Sampaio JU1992]1. Angle btw lower LP infundibulum & renal pelvis2. Diameter of the LP infundibulum3. Spatial distribution of the calyces

– But they are controversial

• How do they affect?– Lower pole infundibulopelvic (LIP) angle as define as: – Angle btw lower border of the pelvis with medial border of the LP infu

ndibulum [Keely EU1999]– Angle btw central pt of renal pelvis & central axis of LP infundibulum

[Elbahnasy JU1998]– Elbahnasy found that favourable factors as (LIP>70, infundibular lengt

h < 3cm & width > 5cm) All 3 all clear vs 16% if none– But other studies show conflicting result

Any way to improve SFR in ESWL of LPS?

• Pace JU 2001

• Percussion , diuresis and inversion (PDI)

• SFR 40% (PDI) vs 3% (observation gp)

ESWL vs PCNL vs URSL• PCNL vs ESWL : Lower Pole I [Albala JU2001]

– Prospective multicenter RCT , LPS < 3cm, SFR at 3m– SFR: PCNL (95%) vs ESWL (37%)– Complication: PCNL (23%) vs ESWL (12%) [insignificant]– Conclusion:

• ESWL = PCNL for treatment lower pole stone < 10 mm• PCNL should be indicated for LPS > 10 mm

• URSL vs ESWL: Lower Pole II [Pearle JU2005]– LPS < 1cm, SFR at 3m– SFR: 50% (URS) vs 35% (ESWL)– SFR: URSL 15% better than ESWL (not significant)– Conclusion:

• ESWL = URSL for LPS < 1cm• ESWL has shorter txn time & recovery, better acceptance • Thus URSL can be offered if ESWL failed as Lower morbidity than P

CNL

Counseling

• LPS < 1cm:– Offer ESWL as less invasive

• LPS 1-2cm: – PCNL, RIRS, ESWL are all acceptable options– URSL or PCNL : less depend on lower pole

anatomy

• LPS > 2cm: – PCNL : outcome independent on stone size

and renal anatomy

Lower pole stone

Calcyceal diverticulum stone

What is calyceal diverticulum?

• Congenital in origin• Non-secretory urothelial-lined compartmen

ts that communicate with collecting system• Pt of communication often very narrow• 25% associated with stone, which will not

pass• Other than treating stone obliteration of

diverticulum during PCNL is needed

What is the SFR?

• ESWL 30%

• URSL + incision 70%

• PCNL + obliterateion 90%

If ESWL failed to clear fragment , why?

• Calyceal diverticulum

• Stone is too hard (ca oxalate monohydrate)

Horseshoe kidney stone

Horseshoe kidney

• Prevalence: 1 in 400• Pathology: abnormal medial fusion of the meta

nephric blastema failure of ascent and rotation of kidney (by IMA)

• Anatomical difference: 1. Kidney in more caudal position

2. Renal pelvis is anterior to all calyces

3. Ureter insert high and lateral on renal pelvis

4. Calyces point posteriorly , lower pole calyces point caudal and medially

Management• ESWL:

– Reasonable 1st line treatment– Problem:

• Difficulties in stone location (medial rotation , bowel gas, bone ) • Impairment of drainage (dilated collecting system, urinary stasis & high inser

tion of ureter) • URSL:

– For small sympotomatic stone not responding to ESWL– Flexible instrument for tortuous ureter & complicated intra-renal anatom

y– Reasonable SFR

• PCNL: – For stone >2cm , failed ESWL & URSL– Puncture: Upper pole posterior calyx – Tract is more medial (increase risk of bowel injury , less pulmonary injur

y) – Use flexible instrument to reach lower pole– SFR: 70%

Ureteric stone

Presentation

• Sudden onset of severe Flank pain that is colicky (waves of increasing severity are followed by a reduction in severity, but it seldom goes away completely)

• It may radiate to the groin as the stone passes into the lower ureter

• Patient moves around, trying to find a comfortable position

Investigation

• Bld

• MSU

• Dip stick hematuria– sensitivity for detecting ureteric colic

• ~95% on the first day of pain,• 85% on the second day• 65% on the third and fourth days

• pregnancy test in premenopausal women

NCCT

1. Greater specificity (95%) & sensitivity (97%) for dx of ureteric stone

2. Can identify other non-stone cause of loin pain3. No contrast injection need (RFT)4. Faster (min)5. Cost equivalent to IVU in high volume centerIVU: • Less radiation exposure• Show level and degree of obstruction

NCCT

• Can also predict fragility of stone under ESWL:• We observed that for calcium stones, the number

of SWs to comminution was generally less than half the stone CT attenuation value in Hounsfield units (in those w/ 3-mm scans).

• This "half-attenuation rule" predicted the number of SWs needed to complete fragmentation for 95% of calcium stones (24/24 calcium oxalate monohydrate, 13/13 hydroxyapatite, 8/10 brushite stones).

• Saw K C et al Calcium stone fragility is predicted by helical CT attenuation values. J. of Endourology 2000 Aug;14(6):471-4

Mx of acute renal colic

• Pain control: NSAID• MOA: by smooth muscle relaxation and reducing

ureteral peristalsis• Caution: Can affect RFT in patient with an

already reduced function• Ev:

– Cochrane review 2005– Opioid vs NSAID– NSAID: lower pain score, less likely to require rescure

medication– Opioid: more adverse effect (Nausea)

• If suboptimal pain control• Add opioid analgesics e.g. dologesic/ pethidine

Prevent recurrent colic

• Double-blind, placebo-controlled trial• Diclofenac 50mg TDS x 7 days after discharge vs

Plecobo• Result:

– significant fewer colic (p < 0.01)– difference was greatest during the first 4 treatment days

• Conclusion: oral treatment with diclofenac was effective as short-term prophylaxis of new colic episodes, especially during the first 4 days, and reduces the number of hospital readmissions significantly. The stone passage rate appears not to be affected

Mx: Renal colic

• Medication: Pain relief – Voltaren SR 100mg QD PO PRN (RFT) – Pepcidine 20mg BD PO– Pethedine 50mg Q6H IM PRN

• Medication: antibiotics ?

Do we need to over hydrate patient?

• Reason: increase urine output to “Flush” the stone out ?

• In fact, renal blood flow and UO fall in episode of obstruction

• Excess fluid excretion will cause greater hydronephrosis further impair peristalsis

Treatment options

• Tailored to individual patient: • (past health, obesity, stable clinical

condition, responding to analgesics)• 1. Observation and medical therapies• 2. Ureteroscopy• 3. ESWL• *2007 Guideline for the management of ureteral

calculi. Gleen M. Preminger et al, Journal of urology 2007 dec vol 178; 2418-34*

MET• Chances of spontaneous passage of stone

– <4mm : 90%– <5mm : 70%– 5-10mm: 50%– Proximal 25%, mid 45%, distal 70%– Average time for spontaneous stone passage

for stones 4–6 mm is 3 weeks– Stones that have not passed in 2 months are

unlikely to do so

• Effects: Ureteral SM relaxation , Limits pain, Accelerated SFR

MET• For stone < 5mm : no additional benefit with MET• For stone 5-10mm , MET with alfa blocker is suggested

when: – No contraindication:

• Pain not controlled• Septic• Derange in RFT• Hypotension

– Benefit: 29% more patient will pass their stone than control, less colicky & analgesic requirement

– Risk: 5% drop out due to hypotension

• Ca channel blocker: only 9% more (not significant) • CCB vs AARB: 20% improvement in SPR with alpha bloc

kers [MA Hollingsworth Lancet. 2006]• Single use of corticosteroid is discourage

• Time for stone passage: 4-6 weeks• Vast majority of trials were limited to p

atients with distal ureteric stones• Tamsulosin is most studied , but all alfa blockers

works well class effect (YILMAZ JU2005)• MET using tamsulosin resulted in a $1132 cost

advantage over observation (Bensalah et al. EJU 2008)

• MET in paed gp is not effective [Aydogdu JU2009]

Mechanis of Action• Ureter SM relaxation• Alpha-1 adrenergic receptor

anatagonist in ureter in humans and animals

• Density of alpha1-anatagonist significantly higher than alpha2/ beta

• Prevalence of alpha1a (subtype) in human

Inhibit basal tone, peristaltic frequency and ureteral contraction

Decrease basal and micturating bladder neck pressure

Decrease intraureteric pressureIncrease fluid transport ability

Facilitate spontaneous expulsion of ureteric stone

Definitive treatment

• For stone >10mm: No recommendation can be made for spontaneous passage (with/without therapy)

• Consideration factors: – Stone size & location– Renal function– Presence of a normal contralateral kidney– Tolerance of exacerbations of pain– Job and social situation– local facilities

Stone removal

• Based on the: 2007 Guideline for the Management of Ureteral Calculi (joint EAU/AUA nephrolithiasis guideline Panel)

• Both ESWL and URS should be discussed as initial treatment options

• Stone free rate, anaes, additional procedures and complications

• URS has better chance of stone free with single procedure , but higher complication rates

• URS has greater stone-free rate for majority of stone stratifications

Stone free rateESWL URSL

Distal ureter Overall 74% 94%< 10mm 97%> 10mm 93%

Mid ureter Overall No difference (86%)

< 10mm

> 10mm

Proximal ureter Overall No difference (80%)

<10mm 90% 80%

>10mm 70% 80%

Open and Lap

• In difficult situations– Very large impacted stones– Multipler ureteral stones– Concurrent conditions requiring surgery

• Lap Ureterolithotomy: – Alternative to open surgery– Less successful in distal ureter then mid/proxi

mal– Median stone-free rate: 88%

Conclusion

• The more distal the stone, more in favor of URS

• SFR were consistently higher for smaller stones

• URS SFR show less size dependence• The data for middle ureteral calculi may

not be as reliable as the overall outcome data (smaller sample size)

• A higher retreatment rate for SWL

What is cost effectiveness between URSL VS ESWL?

• Observation was least costly if no extra cost was incurred by failed observation

• Ureteroscopy was less costly than ESWL for stones at all ureteral locations

• *all patients in URS groups were stented• *URS as an out-patient procedure• *Based on US health system

– Lotan et al. Management of ureteral calculi: cost comparison and decision making analysis. Journal of Urology, 2002. Vol 167, 1621-29

When is drainage required?

1. Pain that fails to respond to adequate analgesics or recurrent pain

2. Associate fever and sign of sepsis (vitals, WBC)

3. Impaired RFT (obstructed solitary kidney / bilateral ureteric stone)

4. Obstructed stone > 4-6 weeks5. Personal occupation reasons (pilot, contr

ol machine, driver, etc)

In obstruction : PCN or JJ?PCN

Advantage: •Rapid decompression•No manipulation of ureter to flare up sepsis•Low failure rate•Monitor UO from kidney•Accessible tract for future use

Disadvantage: •Require radiologist•Injury to other organs•Nephrostomy bag

JJDisadvantage: •Takes time to perform•Manipulation of ureter (sepsis and injury) •Failure rate (impact stone)•Fail to monitor UO •NO accessible tract

Advantage: •Performed by urologist•Able to dilate ureter for future txn•NO risk of injury to other organ•Internal drainage

Management of stone with PUJOManagement of stone with PUJO

What is the management of stone with PUJO?

• Either percutaneous endopyelotomy or open reconstructive surgery

• Transureteral endopyelotomy with Ho:YAG laser endopyelotomy

• Incision with an Acucise balloon catheter

Treatment of Treatment of pediatrics stonespediatrics stones

Investigation: • < 1% of stone in patient <18 years• Doppler USG: Severity of obstruction

– The ureteric jet – Resistive index of the arciform arteries– US will fail to identify stones > 40%

• NCCT & IVU : – detect 95% of stones (rarely need sedation)– Provide anatomical and functional info

• MRU: – Cannot be used to detect a urinary stone– Provide detailed information of anatomy , the location of an obstruction or

stenosis in the ureter, and the morphology of renal parenchyma• Urine:

– serum chemistry and 24-hour urine collections• Identify underlying pathology:

– VUR– PUJO– Neurogenic bladder or other voiding difficulties

Txn: WW

• Spontaneous passage of a stone is more likely to occur in children than in adults

• < 5 mm are likely to pass spontaneously in up to 98% of paediatric patients

• Use of MET is not proven in paed age gp

Txn: ESWL vs URSL

• Indications for ESWL (same as adults) stones with a diameter up to 20 mm are ideal cases

• GA need: 30-100% (age and type of lithotriptor) • URS: primary / after failed ESWL • Semirigid URS: 4.5 and 6.0 F • Flexible URS: 5.3 F• ESWL: less efficient (cystine, brushite, Ca oxalat

e and anatomic abn)

What are stone-free results for pediatric patients?

• The very small number of patients in most groups, particularly for URS, makes comparisons among treatments difficult

• SWL may be more effective in the pediatric subset than in the overall population, particularly in the proximal and mid ureter

• Stone-free rate: – 67-93% (short term studies)– 57-92% (long term FU studies)

• Retreatment rate: 14-54 %• Need for ancillary procedures: 7-33 %• Residual fragments should be closely FU

Ureteral stone

• Spontaneous passage: 98% of <5mm• ESWL: txn choice for most stone, success rat

e fall as stone passed to distal parts• Overall SFR: 80-97%• Success rate for proximal and distal stone:75

-100%• URS is the treatment of choice in mid and dis

tal ureteric stone in children• Flexible URS : for proximal ureteric stone/ lo

wer pole stone <1.5cm

ESWL for ureteric stone

• Txn of choice for proximal ureteric stone

• Difficult case:– >10mm , impacted stone– Ca oxalate monohydate / Cystine – Unfavourable anatomy

• Stent is rarely need

• Ureteral pre-stenting: decrease SFR after initial txn (retreatment rate: 12-14%)

Paediatric

• ESWL may be more effective in mid & lower ureter

Stones in pregnancyStones in pregnancy

Physiological change• Increase cardiac output• Increase in vascular volume, renal output (+60%), GFR (+40-65%)• 1cm kidney size increase• Increased rate of filtered Cr/Ur/Na/Ca/urate• Decrease Serum Cr level • Hypercalciuria

– Increase intestinal Ca absorption– Increase renal Ca filtration– Increase in 1,25OH-D3 produced by placenta

• Same incidence of stone as increased inhibitors (e.g. citrate, Mg, glycoprotein)

• More alkaline urine due to respiratory alkalosisIncidence of ureteric stone: • 1 in 2000• Most in 2nd or 3rd trimester• Significant risk of pre-term labour

Differential diagnosis of flank pain

• Physiological hydronephrosis

• Ureteric stone

• Placental abruption

• Appendicitis

• Pyelonephritis

• All other cause of flank in non-pregnant women

Physiological changes

• Physiological dilation of upper tract– Occurs between 6th and 10th weeks (7weeks)– Disappears 4-6 weeks after delivery– 90% right hydronephrosis at 3rd trimester– Right side predominant

• Progesterone with ureteral smooth muscle relaxation

• Uterine dextrorotation• Compression by ovarian and uterine vein• Protection of left ureter by sigmoid

Ultrasound

• First line investigation: Sp 34%; Sn 86%• Cannot differentiate physiological vs patholog

ical dilation– Dilation up to pelvic brim: physiological– Dilatation below pelvic brim : distal obstruction

• 1st trimester: right <18mm; left <15mm• 2nd/3rd trimester: right <27mm; left 18mm• Look for absence of ureteral jet• Resistivity index >0.7 or difference from the

other kidney > 0.06

Effect of radiation1. Congenital malformation: reduced head circumference/ microcephaly, hypo

plasia of the genitalia, hypospadia, micropthalmia, cataract2. IU growth retardation3. Mental retardation4. Miscarriage5. Cancer risk (leukaemia) 6. Mutagenic effects (inherited disease in offspring) • Fetus most at risk : 4-10 week (1st trimester)• Radiation dose > 150mGy significant increase risk of malforation• Radiation dose < 100mGy unlikely to have adverse effect• Radiation dose < 50mGy negligible effect (National Council on Radiation

Protection) • Majority of diagnostic procedure did not involve fetal exposure

>50mGy (5000mrad)– 1 min fluoroscopy time (2mGy / 200mrad)– X-ray = 1mGy/radiograph

• American College of Obstetritian and Gynecologists guideline – Exposure to X-ray during pregnancy is not an indication for therapeutic abortion

• Thus for radiation dose > 150mGy: • 100 KUB• 88 IVP (6 shot)• 12.5 CT abd , 4 CT pelvis• 250 times JJ insertion

However, every healthy mother…• 3% risk of birth defect• 15% for miscarriage• 4% prematurity• 4% growth retardation• 1% mental retardation / neurologic developmental proble

ms(Brent RL, Mettler FA. Pregnancy policy. AJR 2004: 182: 819-822)

• Need to explain that the baby is not guaranteed to absolutely healthy after x-ray explosure

If USG not adequate ? What can be done

• 3 shot IVU: plain, 30s, 20min

• Low – dose CT

• MRU

IVU

• Taken plain, 30s, 20min (3 shots IVU)

• Use high sensitivity film, reduce aperture, digital radiology, lead apron for the side of health kidney

• Radiation exposure• Overlap with fetus• Suboptimal film quality

NCCT

• High dose of irradiation

• Avoid in pregnancy

• Low dose CT with average radiation ~700mrad (7mGy) (Wesley, J of endourology 2007)

MRU

• T2 weighted image• Sensitivity and specificity (100% for decting ureteric

stone)• Patient needs to stay still in the machine in a period

of time in frank pain• Stone as filling defect• Not advised in the course of 1st trimester (Louca 199

9)• High resolution MRI available

Messsage

• Avoid all radiation at 1st trimester

• Use US as first line imaging modality

• Although estimated risk of diagnostic radiation during pregnancy is low, particularly 2nd and 3rd trimester, need to balance the risk of radiation and risk of untreated obstruction

Management of renal colic

• Imaging to confirm the diagnosis• 1st Line : Hydration + analgesia +/- antibiotics• If physiological: usually not require stenting /PCN• Analgesia

– Paracetamol can be used with no risk– Codeine contraindicated at 1st trimester; can be used episodicall

y during 2nd/3rd trimester– Morphine with short duration to avoid maternofetal dependence,

growth delay, prematurely induced labour; avoid at the beginning or or during labor

– NSAID : avoid for premature closure of ductus arteriosus, pulmonary HT, delay or prolong labour, bleeding during delivery

• Alpha-blocker & CCB : unknown risk in pregnancy

Definitive• 65% pass their stone during pregnancy• 50% of the remaining pass after delivery• Relief obstruction:

– JJ or PCN– under LA + USG or GA + limited fluroscopy– Problem: worsen irritative LUTS & repaid encrustation – JJ need to be change 4-8 weeks

• Indication of treatment– intractable pain, nausea, vomiting, febrile urinary tract infections,

 obstructive uropathy, acute renal failure, sepsis, and obstruction of a solitary kidney

• Treatment of stone: – ESWL : cotraindicated– PCNL: not advice for pt positioning & fluroscopy– URSL: safe and effective in all trimester , SFR 70-100%

AntibioticsSafe: • Penicillin: OK • Cephalosporin: OK• Marcolide - Erythromycin (bacteriostatic): OK

Use with cautions: • Nitrofurantoin: avoid in third trimester

– Fetal hemolytic anemia in G6PD deficiency mother– hepatotoxicity, lung toxicity, inadequate urine concentration if GFR<60

• Aminoglycoside (bacteriostatic): CI in 2nd and 3rd trimesters– can cross placental barrier: fetal ototoxicity & nephrotoxicity– Used only for short periods for severe acute pyelonephritis threatening

materal-fetal prognosis

• Sulphonamide : contraindicated in third trimester– Risk of neual tube defect in 1st trimester due to anti-folate mechanism– Risk of fetal anemia in G6PD def mother

• Triamethoprim : contraindicated in first trimester– Neonatal jaundice

Contraindicated: • Fluoroquinolone (bacteriostatic): contraindicat

ed as toxicity to fetal cartilage and joints, tendon damage

• Chloramphenicol: contraindicated in third trimester as “grey-baby” syndrome

• Tetracycline (bacteriostatic): contraindicated as hepatotoxicity, deposit in teeth and bone

• Thiazide: fetal thrombocytopenia(not to be used)• Allopurinol / D-penicillamine: fetal malformation• Pyridium: OK

Ureteral stents

• Under LA / US guidance• Allows return to normal activties• Can be difficult to be placed (trigone deforme

d by uterus, hyperemic mucosa)• Bladder irritation, risk of displacement due to

dilation of upper tract, VUR causing back pain and pyelonephritis

• Avoid incrustation by changing every 4-8weeks, increase fluid intake, control Ca intake, treat UTI

PCN

• LA, US guidance

• Risk of PCN

• Risk of encrustation; change 4-8 weeks

• Esp for very septic patients

URSL

• Risk of procedure: radiation/ureteric injury/ vascular injury

• Reduce discomfort from obstruction• Under locoregional anaesthesia• Ureters dilated already• Use laser rather than EHL ( may induce labour) or

ultasonic lithotriptor (hearing damage)

• ESWL: contraindicated by fetal damage/radiation• PCNL: contraindicated by difficult position, prolong

ed anaesthesia/high radiation / induce labour

Residual stones and Residual stones and fragmentsfragments

CIRF

• Clinically insignificant residual fragments• Most commonly seen after ESWL• Most common site: Lower calyx• NCCT show small fragments > KUB• EAU 2010:

– <=4mm called residue fragment– >=5mm called residue stone

• Infection stone:• 2.2yr, 78% of stone fragment have progression

• Calcium stone: 6yr FU– Stone growth: 26%– Recurrent stone formation: 15%

251

Recommendations

General recommendations on stone treatment

• Infections

• Anticoagulation and stone treatment

• Pacemaker

• Hard Stones

• Radiolucent stones

Infections

• Urine test should always be carried out

• Dipstick sufficient in uncomplicated case

• If infection and obstruction , drainage for several days before staring active intervention

Anticoagulation

• ESWL , PCNL and open surgery contraindicated

• URS can be done with less morbidity

• Reduced risk of throboembolic complications

Pacemaker

• Can be treated with ESWL provided that cardiologist is consulted before

• Implanted cardioverter defibrillators need to be de-activated during ESWL

Hard stones

• Brushite or Ca oxalate monohydrate

• PCNL for ESWL resistent cases

• Chemolytic treatment for brushite stone

Special problems

Recurrence preventiRecurrence preventive treatmentve treatment

How can stone be prevent?• High fluid intake:

– 24-hour urine volume should exceed 2000ml– Protective by reducing urinary saturation of Ca ,oxalat

e & urate– Prolong time to stone recurrence (from 2 to 3 years)– Reduce risk of stone recurrence (12% vs 27%)– One large study found a risk reduction of 29% in

patients with a higher fluid intakeCurhan et al New Engl J Med 1993; 328: 833–8

• Juice: – Grapefruit juice increase risk (high oxalate)– Orange juice beneficial– Cranberry juice no effect

Dietary calcium & ca supplement?

• Low dietary Ca intake is asso with higher risk of kidney stone [Borghi’s RCT (NEJM 2002) and Curham’s large scale epidemiological studies (NEJM 1993)]

• ↓ Ca intake => ↑absorption of oxalate in GI tract (due to decreased binding with Calcium) => ↑urine oxalate excretion => Ca oxalate sat

uration of urine increases rapidly with small increase in oxalate

• Normal Ca diet for most people (1000 mg/day)• Moderate Ca restriction for absorptive hypercalciuria• Ca supplement:

– Small risk of inducing kidney stone with Ca supplement vs no Ca supplement

– Not recommended except in cases of enteric hyperoxaluria– For those who need supplement , consuming supplement with meal or

with oxalate-containing food would reduce risk

Dietary factors• Other dietary modification to reduce stone forma

tion – Low sodium : should not exceed 5 g/day– Low animal protein (0.8-1 g/kg/day)– Vitamin C not > 500mg to 1g /day (precursor of

oxalate)– Small quantities of wine– Vegatatarian diet : alkaline content – High fructose induce hypercalciuria, hyperoxaluria

and hyperuricosuria– Reduce soft drinks– Urate <500mg/day

Dietary factors• Food rich in oxalate:

– Wheat bran, Rhubarb, spinach– Cocoa, Tea leaves, Nuts

• Food rich in urate: – Calf thymus– Liver, kidney – Poultry skin– Herring with skin , sardines, anchovies, sprats

• Excess animal protein result in: – Hypocitraturia– Low pH– Hyperoxaluria– Hyperuricosuria

• High Na intake result in: – ↑ Ca excretion (reduce tubluar reabsorption)– ↓ urinary citrate (Loss of bicarbonate)– ↓ effect of thiazide on ↓ urinary ca

• Combine Na and animal protein restriction ↓ rate of Ca stone formation

Medication

• Pharmacological treatment should be instituted only when the conservative regimen has failed

• The choice of drug therapy should be based on the stone analysis and on the appropriate biochemical investigations

• There are only three drugs with sufficient evidence on stone prevention: – thiazides in hypercalciuria– allopurinol in hyperuricosuria – postassium citrate in hypocitraturia

• Metaanalysis of RCT – medical therapy reduces 20% of CaOx stone recurrence– (Pearle, Pak J Endourol 1999)

Ca stones

What is suggested treatment for patients with specific abnormalities in urine composition?

What is the medical treatment for urate stone?

Thiazide

• Hydrochlorothiazide (25-50mg QD/BD), bendroflumethiazide, trichlorothiazide, Indapamide

• Mechanism– Increase Ca reabsorption in proximal and distal parts

of nephron– ↓ oxalate excretion (↓ intestinal ca absorption)

• SE: – Hypokalaemia, hypocitraturia and hyperuricosuria

• Loss of K should be replaced by K citrate 3.5-7mmol BD (K citrate >>> KCl )

• EAU Indications: hypercalciuria

Alkaline citrate• Potassium citrate (EAU), Na K citrate, Na citrate, K Mg citrate, KHC

O3, NaHCO3• Mechanism of action.

– Alkalinizing salt increase urinary pH increases the excretion of citrate

– reduce the supersaturation with calcium oxalate and calcium phosphate – increase the inhibition of growth and aggregation (agglomeration) of the

corresponding crystal phases• SE: GI upset, hyperkalaemia (!CRF)• Compliance: ~50%• Indications: hypocitraturia• Ev:

– 2 RCT: K citrate significant reduced recurrence rate vs Na citrate

Orthophosphate

• Very weak evidence, NOT 1st line choice• Insufficient evidence to recommend its use• Mechanism of action.

– reduce the synthesis of 1,25(OH)2-D vitamin. • decreased absorption of calcium • reduced calcium excretion; • reduced resorption of bone • increased phosphate excretion, • increases urinary citrate and pyrophosphate (inhibitor of Ca oxal

ate and Ca PO4 crystal growth)

• SE: Diarrhoea, abdominal cramps, nausea and vomiting

• The possible effect on parathyroid hormone needs attention

• Compliance: good

Magnesium

• Not recommended as monotherapy • Combination with thiazide might prove useful• Mechanism of action

– formation of complexes between magnesium and oxalate, thereby reducing the supersaturation with calcium oxalate.

– Inhibit the growth of calcium oxalate / phosphate crystals – ↑ citrate excertion

• SE: Diarrhoea, CNS disorders, tiredness, sleepiness and paresis

• Compliance 70-80%

Allopurinol

• Indication: – hyperuricosuric Ca oxalate stone– uric acid stone

• Mechanism of action– Reduced salting-out effect– Decreased risk of uric acid or urate crystals as promoters of calc

ium oxalate precipitation– Complex formation between colloidal urate and macromolecular

inhibitors, and/or– Reduced excretion of oxalate

• SE: Steven Johnson Syndrome• No effect in patient without hyperuricosuria• Compliance?

Pyridoxine (Vit B6)

• Co-enzyme pyridoxal PO4 increase transamination of glyoxylate ?affect endogenous production of oxalate

• Use together with orthophosphate to tx primary hyperoxaluria Type I or idiopathic hyperoxaluria

• No RCT to show efficacy, but recommended for primary hyperoxaluria Type 1

Enteric hyperoxaluria

• Patients with intestinal malabsorption of fat– After intestinal resection– Jejunoileal bypass for txn of obesity– Crohn’s disease– Pancreases insufficiency

• Loss of fat Calcium bind to fat• Oxalate absorption ↑ hyperoxaluria• Hypocitraturia because loss of alkali• Urine: low pH, low ca, low volume

Treatment

• Restricted oxalate-rich foods & fat

• Ca supplements : enable ca oxalate complex formation in the intestine

• Ca should be given at meal teims

• Oxalate-binding agents: marine colloid (Oxabsorb)

• Increase fluid intake

• Alkaline citrate ↑ urinary pH and citrate

Recommendations

• Ca and oxalate influence the supersaturation with equal power essential to correct abnormalities of both variables

• Incomplete distal RTA : given K citrate

• In absence of common biochemical risk factors: water load had +ve effect on supersaturation and crystallisation

Intracorporeal Intracorporeal energy formsenergy forms

Outline

• Rigid – Ballistic lithotripsy– US lithotriptor

• Flexible– EHL– LASER

Lithoclast• Ballistic (Pneumatic) lithotripsy• Compressed air from an external supply• Fires to a metal projectile• Kinetic energy delivered to the probe and then fragment

the stone by Jackhammer effect• Vs electrokinetic lithotriptor

– Same fragmentation, retropulsion, safety margin– EKL has heavier handpiece, but cheaper

• Fragmentation rate 73-100%

• Avoid bowing of the probe to reduce power loss

• There is a pneumatic disintegrating probe for flexible scopes

• Safe on ureter with perforation rate <1%

• No heat production, less thermal injury to ureter

Lithoclast

• Pros– Cheap in maintenance– Effective– Safe

• Cons– Retropulsion– Need rigid instrument– Fragment to larger pieces– Fragments not removed (except Lithoclast master)

Electrohydrolic lithotripsy

• Underwater spark plug• Voltage/ current to two concentric electrode with different

voltage polarities, insulated and 1mm apart• Electrically generated electric spark• Momentary production of heat in a localized area,

causing the irrigant (water) to vaporize and form a gas bubble

• Expansion and collapse of bubble generates shock wave in 1/800 second– Symmetrical (~1mm): strong secondary shockwave– Asymmetrical (~3mm): microjets

• Probe at 1mm from stone (shockwave not focused)

EHL• Pros

– Effective– Use in flexible instrument, as small as Fr 1.6– Relatively inexpensive machine

• Cons– Potentially damage to surrounding tissue

(ureteric perforation risk 17.6%)– May need to revise the probe for hard stones– Residual stone fragments (3 month stone free rate

~84%)– Work worse on smooth stone surface

US lithotriptor• US generator transmitting US waves to a hollow probe resulting

vibration of the probe tip• Probe tip causes the stone to resonate at high frequency and

breaks• Drilling or grinding action for stone fragmentation• Normal tissue does not resonate less damage; but heat from the

tip could damage• Need good irrigation system to cool the probe• Allows suction of stone fragments• Avoid use in pregnant women in URSL as unknown risk of hearing

damage to fetus• High temperature of the probe causing risk of ureteric injury, but

reported to be good for steinstrass• Fragmentation rate 69-100%

US lithotriptor

• Factors affecting stone fragmentation efficacy (Campbell)

– chemical composition of the stone (cystine, calcium oxalate monohydrate, and uric acid being the most resistant)

– Size– Density– Surface structure (worse if smooth)

US lithotriptor

• Pros– Safe– Remove stone fragments– Less likely for retropulsion

• Cons– Relatively slower fragmentation (better

combine with lithoclast master)– Cost for probe breakage– Rigid instrument

What is cyberwand?

• Dual ultrasonic lithotriptor because it employs two separate ultrasonic probes that vibrate at two different (high and low) frequencies via one hand-piece to improve efficacy

• Inner probe with high frequency, for larger stones

• Outer probe with low frequency, for small stones• With sucker• One pedal

Laser Laser

LASERLASER• Light Amplification by Stimulated Emission of

Radiation• Coherence (light in parallel), Monochromacity (in

same wavelength), Collimation (in phrase)• Photoacoustic effect : generation of shockwave

by creating “plasma” bubbles and collapses• Photothermic effect: vaporization of stone by

heat

LASER

• Pulsed laser : to keep stone vaporization but decrease heat dissipation

• Two form of lasers in stone fragmentation– Pulsed dye laser (Coumarin green dye)

• 1us duration, 504nm wavelength• Absorb by stones except cystine but not tissue, poor with cal

cium oxalate monohydrate• Coumarin dye is a toxic disposable• High cost• Fragmentation rate 80-95%• Warm up time 20min

Laser

• Holmium:YAG laser– Pulse duration 250-350us (produce elongated cavitati

on bubble with weak shockwave)– Wavelength: 2140nm– Absorb by water, zone of thermal injury 0.4mm– Stone fragmentation mainly by photothermal effect– Work on all stones– Fragmentation rate 91-100%– More compact machine, 1min warm up time

Holmium:YAG Laser

• Pros– Work on all stones– Can fragment to tiny fragments– Safe for surrounding structures– Less retropulsion– Flexible

• Cons– Expensive machine– May need longer time for fragmentation– Need eye protection(damage cornea if <10cm)– Damage instruments

Alexandrite laser

• Solid state laser

• NOT a pulsed-dye laser

• Wavelength 750nm

• Stone fragmentation rate 50%

• Complication of ureteric perforation

• FOR REMOVAL OF SKIN TATTOO

Laser Safety

1. Warning signs in operating theatre2. Wear goggles3. Check if aim beam intact4. Operate the laser when the fiber is inside patient’s body5. Start from low setting (0.6J, 6Hz)6. Keep >2mm from urothelium7. Keep fiber tip in view at all times8. Do not discharge the laser fiber inside the working chan

nel or on guide wires and baskets9. Do not have one person controlling the fiber and anothe

r the foot pedal10.Do not pass the fiber tip through the back wall of stones

Factors affecting laser fragmentation efficacy

(Christian Seitz,EU 2007)• Position : distal ~95%; proximal ~75%

• Impaction for upper ureteric stone (86% vs 67%)

• Independent on– Size– Composition– Presence of hydronephrosis– Impaction for lower ureteric stone

Fragments after lithotripsy: Active retrieval or Spontaneous passage?

Oscar Schatloff (JU, 2010)

• RCT, 60 patients with URS + Holmium laser

• Intra-op fragments retrieval by grasper vs exhaustive lithotripsy

• Higher rate of unplanned medical or ER visit 30% vs 3% without fragments retrieval

• Rehospitalization / ancillary treatment, stone free rate worse but not significant

Upper ureteric stones• Prefer Holmium:YAG laser

– Higher stone clearance rate• Vs EHL : 100% vs 67%(Teichman, 1997)• Vs lithoclast : 96% vs 70% (Sun, 2001)(RCT showed similar fragmentation but decreased retrop

ulsion, Garg 2009)– US lithotriptor need larger URS and prior dilation. Also

potential problem of heat generation from probe and retropulsion

– Safe on ureter– Produce fragments ~2mm vs lithoclast, pulsed dye las

er or EHL (Teichman, JU1998)

Bladder stones

• No good study comparing different modalities

• Razvi (Journal of endourology, 1996)

– Mechanical lithotripsy 90% - stone too hard, breakage of lithotrite

– US lithotripsy 88% - stone too hard– EHL 63% - stone too hard, hematuria– Lithoclast 85% - ineffective probe contact, pro

static channel bleeding obscuring view

Bladder stone

• I prefer lithoclast– Proven safety in animal study– Effective device as shown in Razvi’s study in

1996– Durable device and cost effective– Lithoclast Master if available in the centre to d

ecrease stone load for retrieval

Renal stones during PCNL

• No study on optimal device for PCNL• May need a combination of devices• US lithotriptor

– effective and could remove small stone fragments– Study on CIRF in ESWL with 21% stone recurrence and retreat

ment (Osman, EU 2005)

– Avoid compress the stone to renal pelvis with pressure

• Lithoclast– Produce larger fragments to be removed

• Laser– Allows use of flexible instruments

If you see some yellowish If you see some yellowish concretion beneath the papillaconcretion beneath the papilla

What is it?

Randall’s plaqueRandall’s plaque

J Urol 2008; 179: 1676-1682

• Areas of damage associated with subepithelial plaques on renal papillae, composing of Ca apatite

• Originates from basement membrane of thin limbs of loop of Henles, that subsequently extends through medullary interstitium to a subepithelial location

• When eroded through the urothelium, constitute a stable anchoring surface that Ca oxalate crystals can nucleateand growth as attached stones (Evan 2003)

Q. IVU

• This IVU of a 45 year old lady present with dysuria.

Q.

• A. What abnormalities are shown?– Bilateral ureterocele with stone in L ureterocele (1)

• B. What is the most appropriate treatment?– Endoscopic incision of ureteric meatus with stone rem

oval. (1)

• C. What complication of treatment may occur?– VUR (1)

NephrocalcinosisNephrocalcinosis

KUB of patient with renal colic. Diagnosis?

Patient with loin pain, KUB

Patient with loin pain, IVU

Patient with loin pain

• What is seen?

• What is the diagnosis?

• What are the complications?

Medullary nephrocalcinosis

• Hyperparathyroidism, RTA, medullary sponge kidney, chronic pyelonephritis, milk alkali syndrome, vitamin D excess

• Segmental cases occur in medullary sponge kidney - present in roughly 1in 200 IVU, M=F, commonest in adolescence and thrid and fourth decade

• RTA is the commonest cause in young age group• Present in 1:200 IVU, stone common, UTI and

hematuria can occur

Microscopic hematuria

• 40 years old lady with microscopic hematuria

• KUB done

Microscopic hematuria

• What is the abnormality?– Cortical nephrocalcinosis

• What are the possible causes?– After acute cortical necrosis (shock), chronic

GN, Alport syndrome (nephritis associated with deafness), toxins (eg methoxyflurane anesthesia)

Urinary obstructionUrinary obstruction

What is the ureteric pathway in What is the ureteric pathway in female/male?female/male?

• Pass through parametrium, (tunnel through cardinal ligaments of uterus)

• Course anterior to vagina before entering bladder

• Far away from round ligaments• 1.5cm from cervix on each side• Course deep to broad ligaments

• Cross anterior to vas before entering bladder

What is physiology of GFR?

• GFR relates to glomerular filtration pressure (depends on renal blood flow) and tubular pressure

• Renal blood flow = (aortic pressure – renal venous pressure) / renal vascular resistance

Physiology of urine flow from kidney to bladder

• Transport of urine is intermittently by wave of perstalitic contraction of the renal pelvis and ureter

• Origin of peristaltic wave (pacemaker cell) in proximal region of renal calyces

• Frequency of contract independent of urine flow rate• Electrical activity is conducted distally from one muscle cell to anoth

er (proximal most are dominant) • Proximal ureter receive bolus of urine stimulated to contract while

distal ureter segment relax urine is projected distally• Ureter received Sym & parasym input which affect frequency and vo

lume transmitted• Ureter must coapt to propel urine• Ureteric resting pressure : 0-5 cmH20• Contraction pressure: 20-80cmH20• Ureteric peristalic wave: 2-6x/min

Acute unilateral ureteric obstruction

Time (hr) Ureteric pressure

Renal blood flow

Effect

Phase 1 0-1.5 Rises rises Afferent arteriole dilatation

(PGE2 & NO)

Phase 2 1.5-5 Continue to rise

Falls Efferent arteriole

constriction

Phase 3 Beyond 5 Fall Falls Afferent arteriole

constriction

Bilateral ureteric obstruction?

Time (hr) Ureteric pressure

Renal blood flow

Effect

Phase 1 0-1.5 Rises Rises Afferent arteriole dilatation

Phase 2 1.5-5 Rise Significantly lower than

UUO

Phase 3 After 5 Remain elevated

Fall

The prognostic value of renography in ureteric stone obstruction

• Stone size showed no correlation with functional impairment

• Infection proximal to ureteric stones accelerated kidney damage

• <14 days - 100% recovery• 15-28 days - 80% recovery • >28 days - 65% recovery

– Holm-Nielsen A, et al.Br J Urol. 1981 Dec;53(6):504-7.

USG for hydronephrosis/ obstruction

• Mainly anatomic study• Can assess cortical thickness and thus est

imate fx• If with doppler, then more info on function• > resistive index (RI)

– If RI > 0.7 then more suggestive of obstruction– RI means (PSV-EDV)/PSV– RI alone not sensitive enough– If RI + hydro > more predictive for obstruction

Symptomatic relief

• Analgesic• Choice: can be panadol NASID nacrotics• Preferred NSAID

– Strong pain-killer: reduced prostaglandin synthesis, reduce potentiation of nociceptor

– Help to reduce pressure in collecting system (mechanism: reduce RBF)

• nacrotics may cause nausea and emesis and drowsiness – not good choice, but if already impaired RFT or bil hydros, then preferred

Post obtructive diuresis

• Usu. Defined as >200ml/ hr for 2 consecutive hr• Usu. In bil obstruction or obstruction in solitary fx kidney• Can be physiological and pathological• Physiological:

– Renal excretion of previously accumulated water and salt due to obstruction

– Solute diuresis from accumulation of urea in ECF

• Pathological : – Impaired renal sodium and water handling (i.e. impaired concentrati

on ability)– Loss of countercurrent mechanism in the medulla (loss of corticome

dullary concentration gradient)– Accumulation of natri-uretic peptide (AVP)

2 phase recovery in most patients• Early: within 2 weeks: Tubular –sodium and water balance is restore

d (BP normalises and signs of CCF diminish) and plasma creatinine falls

• Later: Between 2-12 weeks: Glomerular phase –recovery of GFR?

Mechanism– Reduced medullary solute gradient (down regulation of Na trans

port in thick ascending limb of loop of Henle)– Increase endogenous ANP– Reduced responsiveness to ADH (down regulation of aquaporin)

mx

• Monitor fluid status, electrolyte, Ur and Cr and urine output

• If normal sensorium, normal electrolyte > allow free fluid intake

• If altered sensorium, IVF with amount less than maintenance requirement

• If patho diuresis, > more close monitoring, watch for hypovolemia and e- disturbance and replace IV accordingly