Urinary Tract Obstruction 2

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Urinary Tract Obstruction

Introduction

Urinary Tract Obstruction can be the result of various pathological processes, intrinsic and

extrinsic to the renal system. Symptoms and signs of obstruction are often mild, occurring over

long periods of time and requires a high index of suspicion for diagnosis.

Def inition

Urinary Tract Obstruction is an interference with the flow of urine at any location along the

urinary tract. An obstruction may be anatomic or functional; it impedes flow proximal to the

blockage, dilates the urinary system, increases the risk for infection and compromises renal

function.

Caus e so f Urinary Tract Obstruction

The causes of Urinary Tract Obstruction can be grouped by the site at which the obstruction

occurs. Four examples of these causes are Calculi occurring within the lumen, Ureteric, Urethral

or ureterovesical stricture that occurs within the wall, Phimosis and tumors.



Certain points along the urinary tract are more susceptible to obstruction and these include:

1. Pelvi- Ureteric junction (PUJ)

2. Where the ureters cross the pelvic brim, at the level of the iliac vessels.

3. Vesico -ureteric junction (VUJ)

Obstuction can be either unilateral or bilateral:

Unilateral- calculi and neuromuscular malfunction at the junction of the renal pelvis and

ureter are the most common causes of this form of obstruction.

Bilateral- In the developed world, 75% are due to prostate, calculi and bladder tumors.

R e nal Calculi are hard, small stones that form in the renal structures. Calculi are most

commonly made up of Calcium crystals. These Calculi may be found anywhere from the kidney

to the bladder. Their size may vary from minute granular deposits, called sand or gravel, to

bladder stones as large as an orange.

These stones may form when there is a deficiency of substances that normally prevent

crystallization in the urine, such as, citrate, magnesium, nephrocalcin and uropontin. The fluid

volume status also plays a role in the calculi formation in that the stones tend to occur more

often in dehydrated patients. Renal Calculi can also be caused by either increased urine pH (e.g.

calcium carbonate stones) or decreased urine pH (e.g. uric acid stones) Certain dietary habits or



drugs can also result in stone formation also urine stasis (no movement) anywhere in the

urinary tract, increases the likelihood of stone formation.

Depending on where a stone forms, it may be called a kidney stone, ureteral stone, or bladder

stone. The process of stone formation is called urolithiasis, renal lithiasis, or nephrolithiasis.

Calculi formation is also influenced by three endogenenous factors;

(1) Crystal growth inhibiting factors. These are substances that are capable of minimizing

the risk of calcium phosphate or calcium oxate precipitation in the urine and ensuing

stone formation. These substances include pyrophosphate, potassium citrate and

magnesium.

(2) P article Retention. This occurs primarily at the papillary collecting ducts. Urinary stasis,

anatomic abnormalities or inflamed epithelium within the urinary tract prevents the

flushing of crystals from the system, escalating the possibility of the development of

calculi.

(3) Matrix . This is an organic material found in the urinary calculus. Some urinary calculus

contains significant amounts of organic matrix caused by tissue damage.



Som e Common Signs and Symptoms

These includeinfection (pyelonephritis and cystitis with chills, fever and dysurea) can occur due

to constant irritation by the stones. Pain and renal colic; when the stone is lodged in the ureter,

it is common to have pain radiate down to the genetalia. The pain results when the stones

prevent the urine from draining. Other signs and symptoms include hematuria from irritation

done by the stone. Urinary Retention can occur if the stone obstructs the bladder neck. Some

clients may experience nausea, vomiting and diarrhea because of the proximity of the gastro

intestinal structures.



M anag e m e nt o f R e nal Calculi

Renal Calculi are treated medically if possible. The basic goals of management include,

eradicating the stone, determining the stone type, to prevent nephron destruction, to control

infection and to relieve any obstruction that may be present. If possible fluids are encouraged;

this increases the hydrostatic pressure behind the stone, assisting it in its downward passage.

Intravenous fluids are administered to hydrate the client and help flush the stone out of the

body provided that the stones are 5mm or smaller because if they are larger the wont pass out.

To detect the passage of stones all urine passed out is strained and pain medication such as

morphine is given to relieve the pain Interventions are used when the client is unable to pass

the stones, infection has developed, impaired renal flow or continuous severe pain.

Lithotripsy is a form of therapy that is used to break the stones into smaller parts that can be

removed or urinated out. Blood in the urine is common after this procedure. Some clients

require surgery and the type of surgery to be performed depends on the location of the stone.

Endoscopic procedures or open surgery can be used. Endoscopic procedures for the bladder

include a cystoscopy for small stones and a cystolitholapaxy for larger stones. The open surgery

procedure would include a cystotomy for stones in the bladder and an ureterolithotomy for the

ureter. If the stone is very large, a nephrolithotomy (surgical incision into the kidney to remove

the stone) is performed.



L ithotripsy

Cytoscopy



D iagnostic Evaluation

The diagnosis of renal calculi can be made by the use of a kidney-ureter-bladder examination,

ultrasonography, intravenous urography,or retrograde pyelography.Intravenous

pyelogram.Blood chemistries and a 24-hour urine test for measurement of calcium, uric acid,

creatinine,sodium, pH, and total volume are part of the diagnostic workup.

Pr e disposing Factors o f Urinary tract Obstruction



These factors would include, diet, medication, lifestyle factors and genetics. Obesity and weight

gain increase the possibility of kidney stones due to increased excretion of overabundant

calcium, oxalates (calcium stones, usually formed with oxalate, recurrently accompany

conditions that cause bone resorption, including immobilization and renal disease) and uric acid

(uric acid stones frequently accompany gout, a disease of increased uric acid production or

decreased excretion.)

Other factors include age in which Urinary Tract Infection occurs in the young (children not

those young at heart) and the old, in older men it is a relatively common condition due to

prostatic enlargement whilst in children it is due to congenital abnormalities such as

hydronephrosis( distension of the pelvis of the kidney).

Another factor is sex, in men urinary tract obstruction is most frequently a result of urethral

stricture whilst, in women, it tends to be associated with pelvic tumors (particularly

gynecological malignancies), prolapse of pelvic structures, or pregnancy.



Tabl e o f Cont e nts

Introduction, Def inition and Caus e s f or UTO«.pg1

R e nal Calculi«pg2

Common Signs and symptoms o f R e nal Calculi...pg3

M anag e m e nt o f R e nal Calculi«pg. 4 & 5

D iagnostic Evaluations«pg6

Pr e disposing Factors o f R e nal Calculi«pg7

Urinary Tract Obstruction 2

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