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EXCRETION UROGRAPHY

By: Sudil Paudyal

B.Sc.MIT 2nd year

IOM,MMC

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Introduction

• Also known as intravenous urography (IVU).

• Most frequently employed radiologic investigation of renal drainage.

• The contrast material is administered intravenously.

• Best method for adults unless use of other methods is specified and is used in examinations of upper urinary tracts of infants and children.

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• Urogram: Visualization of kidney parenchyma, calyces and pelvis resulting from IV injection of CM.

• Pyelogram: Describes retrograde studies visualizing only the collecting system.

• So, IVP is misnomer, should be IVU

• Excretion urography used nowadays.

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Anatomy

Kidneys:• A pair of bean-shaped organs approximately 12 cm long.

They extend from vertebral level T12 to L3 when the body is in the erect position. The right kidney is positioned slightly lower than the left because of the mass of the liver.

Internal structure• Within the dense, connective tissue of the renal capsule,

the kidney substance is divided into an outer cortex and an inner medulla.

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• Cortex-contains glomeruli, Bowman's capsules, and proximal and distal convoluted tubules. It forms renal columns, which extend between medullary pyramids.

• Medulla-consists of 10 to 18 striated pyramids and contains collecting ducts and loops of Henle. The apex of each pyramid ends as a papilla where collecting ducts open.

• Calyces-the minor calyces receive one or more papillae and unite to form major calyces,of which there are two to three per kidney.

• Renal pelvis-the dilated upper portion of the ureter that receives the major calyces.

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• Relations:• Anteriorly, a portion of the liver, duodenum and right colonic

flexure lie in front of the right kidney. the left part of the transverse colon, the left colic flexure, and upper part of the descending colon lie in front of the rest of the left kidney.

• Posteriorly, the psoas muscles lie behind each kidney. The upper part of each kidney lies on the inner surface of the respective twelfth rib.

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• Superiorly, the adrenal glands are sited on the superior surface of each kidney.

• Inferiorly. Coils of small bowel supported on their mesentery lie below each kidney.

• Medially, vertebral column lies between the two kidneys. Immediately in front of it are the great vessels, the aorta on the right and the inferior vena cava on the left and their associated renal blood supply and drainage.

Blood Supply:• Right and left renal arteries respectively, branches of the

abdominal aorta.Nerve supply:• Motor neurones from the autonomic nervous system.

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• The large muscles on either side of the vertebral column cause the longitudinal plane of the kidneys to form a vertical angle of about 20° with the midsagittal plane. These large muscles include the two psoas major muscles. These muscle masses grow larger as they progress inferiorly from the upper lumbar vertebrae.

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• This gradual enlargement produces the 20° angle, wherein the upper pole of each kidney is closer to the midline than its lower pole.

• These large posterior abdominal muscles also cause the kidneys to rotate backward within the retroperitoneal space. As a result, the medial border of each kidney is more anterior than the lateral border.

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Ureters:

• These are two long tubes leading from the pelvis of each kidney to the bladder, descending on either side of the vertebral column and passing forward over the pelvic brim, to enter obliquely into the posterior base of the bladder.

• Are constructed so that urine passes along them by peristaltic action.

• There is an inner lining of mucous membrane supported on a submucosal layer, then a layer of plain circular involuntary muscle, and an outer layer of white fibrous tissue.

• The ureters have a length of approximately 20 cm and an internal diameter up to 3 mm.

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Ureteric constrictions: • The ureters vary in diameter

from 1 mm to almost 1 cm. • Normally, three constricted

points exist along the course of each ureter.

• If a kidney stone attempts to pass from kidney to bladder, it may have trouble passing through these three regions.

• The first point is the ureteropelvic (UP) junction, where the renal pelvis funnels down into the small ureter.

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• The second is near the brim of the pelvis, where the iliac blood vessels cross over the ureters.

• The third is where the ureter joins the bladder, termed the ureterovesical junction, or UV junction.

• Most kidney stones that pass down the ureter tend to hang up at the third site, the UV junction, and once the stone passes this point and moves into the bladder, it generally has little trouble passing from the bladder and through the urethra to the exterior.

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Bladder:• Bladder is situated in the anterior part of the pelvic cavity,

behind and just above the symphysis pubis.• Exact position depends on the degree of distension.• Acts as a reservoir for urine from the kidneys and

subsequently expels it via the external urethra.

• It is a hollow muscular organ lying in the anterior part of the pelvis outside the peritoneum.

• When empty it is pyramidal in shape and presents an apex behind the smphysis pubis, a base anteriorly and a superior and two inferolateral surfaces.

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• The ureters enter the postero lateral angles of the base and the urethra leaves inferiorly at the narrow neck.

• The interior of the bladder is covered with mucous membrane which thrown into folds, except in the trigone between the ureteric orifices, in the contracted state and stretched more smooth when the bladder is distended.

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Indications

• To see the anatomy and physiology of urinary system• Trauma• Calculi- renal, ureteric, bladder• Congenital anomalies- ectopic kidney, horseshoe kidney, renal

agenesis• Infective pathology• Renal tumour• Unknown Haematuria• Renal hypertension• Bladder pathology- diverticula, fistula• Vesico ureteric reflux

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Contraindications:

• Hypersensitivity to iodinated CM• Renal insufficency• Hepato renal syndrome• Thyrotoxicosis,• Pregnancy, (Allow 28 days from childbirth)

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Contrast media:

• Low osmolar contrast media (LOCM)- 300- 600mgI/ml• Adult dose : 50-100ml• Paediatric dose : 1ml/kg

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Equipment:

• Any standard radiographic unit is suitable to perform the procedure.

• High power x-ray generator.

• Immobilization band is usually not applied because the resultant pressure may interfere with the passage of fluid through ureters and may also cause distortion of canals.

• However, compression band is sometimes applied over distal ends of ureters to retard flow of opacified urine into bladder and to ensure adequate filling of renal pelves and calyces.

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Pt. preparation

• NPO for 5h prior to examination. • Pts. should preferably be ambulant for 2h prior to the

examination to reduce bowel gas.• Bowel preparation is necessary to reduce the bowel gas

pattern which may obscure the region of interest.

• The routine administration of bowel preparation use makes the examination more unpleasant for the patients.

• Nowadays it is said to be unnecessary.

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• The technologist must check the patient's chart to determine the creatinine and BUN (blood urea nitrogen) levels. Patients with elevated blood levels have a greater chance of experiencing an adverse contrast media reaction. Normal creatinine levels for the adult are 0.6 to 1.5 mg/dl. BUN levels should range between 8 and 25 mg/100 ml.

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• Nowadays, dehydration is not necessary and doesnot improve image quality.

• Dehydration is contraindicated in the following situations:1. Renal failure2. Myeloma 3. Infancy

• If examination is to be performed on a pt who has previously had a severe CM reaction, consideraton should be given to administering methyl prednisolone 32mg orally 12 and 2 h prior to CM injection.

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SIGNING INFORMED CONSENT FORM:

• Venipuncture is an invasive procedure that carries risks for complications, especially when contrast media is injected. Before beginning the procedure, the technologist must ensure that the patient is fully aware of these potential risks and has signed an informed consent form.

• If a child is undergoing venipuncture, the procedure should be explained to both the child and the guardian, and the guardian should sign the informed consent form.

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Technique

• Venous access via the median antecubital vein is the preferred injection site because flow is retarded in the cephalic vein as it pierces the clavipectoral fascia.

• The gauge of the cannula/needle should allow the injection to be given rapidly as bolus to maximize the density of nephrogram.

• Upper arm or shoulder pain may be due to stasis of contrast in vein which may be relieved by abduction of the arm.

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Films • Preliminary film: Supine, full length AP of

abdomen in inspiration. The lower border of

cassette is at the level of symphysis pubis and the x-ray beam is centred in the midline at the level of iliac crests.

To demonstrate bowel preparation, check exposure factor, and location of radiopaque stones or any radiopaque artifacts.

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• If necessary the position of overlying opacities may be further demonstrated by:

• Supine AP of renal areas, in expiration. The x-ray beam is centred in the mid-line at the level of lower costal margin

Or

• 35° posterior oblique views, or,

• Tomography of the kidneys at the level of a third of the AP diameter of the patient (app.8-11 cm). The optimal angle of swing is 25-40°.

• The examination should not proceed until these films are reviewed by radiologist and claimed satisfactory.

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Films

• Immediate film : AP of the renal areas. This film is exposed 10-

14 s after the injection (app. Arm to kidney time)

Aims to show the nephrogram, i.e renal parenchyma opacified by contrast medium in renal tubules.

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• 5-min film: AP of renal areas. To determine if excretion is symmetrical and is invaluable for

assessing the need to modify the techinque, eg a further injection of CM if there has been poor initial opacification.

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• Compression band is now applied around the patient’s abdomen and the balloon positioned midway between the ASIS i.e. precisely over the ureters as they cross the pelvic brim. The aim is to produce better pelvicalyceal distension.

• Compression is contraindicated:1. After recent abdominal surgery2. After renal trauma3. If there is a large abdominal mass or aortic aneurysm.4. When the 5-min film shows already distended calyces.

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• 15 min film: Supine full length AP There is usually adequate

distension of the pelvicalyceal systems with opaque urine by this time.

Compression is released when satisfactory demonstration of the pelvicalyceal system has been achieved.

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• Release film (full bladder) : coned view of bladder area• Taken to show the bladder. If this film is satisfactory, the pt is

asked to empty the bladder.

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• After micturition film:• Either a full length abdominal film or a coned view of the

bladder with the tube angled 15° caudad and centred 5 cm above the symphysis pubis based on earlier findings.

• Main aim of films is to Assess bladder emptying To demonstrate return of dilated upper tracts with relief of bladder pressure. Aid diagnosis of VJ calculi Dx of bladder tumors Demonstrate urethral diverticulum. Residual vol of urine.

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Additional films:

• Posterior obliques of kidneys, ureters or bladder:

To determine whether the radiopaque shadow is in the ureter or outside.

Position: Pt. is rotated 30-35° in rt or lt side depending on pathology side.

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• Prone film: To investigate pelviureteric and ureteric obstruction as the

heavy contrast laden urine will more readily gravitate to the site of the obstruction.

To displace the overlying bowel gas towards periphery. Position: Pt. lies prone after doing 15 min full film and after 4-

5 min. of lying prone (so that lower ureter is dependent part) full film is taken.

• Tomography- when there are confusing overlying gas shadows in renal areas.

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• AP with caudal angulation: To separate the over shadows by stomach on left kidney. Position: AP position, film of kidney area with 25° caudal tube

angulation.

• Erect film: To determine where or not there is small ureteric calculus, erect oblique film of area of ureter. To demonstrate layering of calculi in cysts and abscesses.

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• Delayed films : may be necessary for up to 24 h after injection to demonstrate the actual site of ureteric obstruction.

• Children: films are taken in 3 min, 15 min, aden post mic after CM injection and further depending upon pathology.

• Pregnancy: film sequence is KUB and 15 min full film.

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Modification in case of pathology:

• In case of suspicious shadows in renal areas: Take lateral film of renal area. Take inspiratory and expiratory film of renal area to

demonstrate the relationship of opacities and filling defects of renal tract.

• In case of renal hypertension: take fast sequences (1min, 3 min, and 5 min film).

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• Ectopic kidney: full film KUB region from immediate to last film.

• Renal agenesis: full fim KUB from immediate to last film. Delayed films upto 24 hours.

• Bladder diverticulum: Abnormal pouch formed within bladder. Lateral film of bladder area.

• Vesicovaginal fistula: lateral film of bladder area.

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• VUJ obstruction: Oblique film of bladder area of obstruction side.

• Suspected renal failure, er urography, inadequate bowel preparation:

High dose IVU (dose of CM upto 600mgI/kg body wt.) is performed.

Common sequences and further delayed sequences ( 1 hrs, 3 hrs, 6 hrs, 12 hrs and 24 hrs) if kidney function is not seen.

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Radiation protection

• Direct lead rubber gonad protection using a half apron.• “Pregnancy” rule should be followed.

• If whole of renal tract is to be visualized, no gonad shielding is possible for the females, but for males the testis can be protected by placing a lead rubber sheet over upper thighs below lower edge of symphysis pubis.

• When bladder and lower ureters are not included then female can also be given gonad protection.

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Aftercare

• General psychological reassurance.

• Needle wound site dressed and checked for extravasation.

• Check patient understands how to receive the results.

• Ensure patient understands any preparation instructions are finished.

• Escort to changing rooms and bid good-bye.

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Advantage/disadvantage

• The strengths of urography are: rapid overview of the entire urinary tract, detailed anatomy of the collecting system,

demonstration of calcifications,

it is sensitive for obstruction, and

low cost,

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The weaknesses are that: • it depends on kidney function,

• it provides little assessment of parenchymal structure (eg. cystic vs. solid),

• the perinephric space is not demonstrated,

• it necessitates the use of radiation and contrast medium, and

• it provides no assessment of glomerular filtration rate.

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Complication

• Due to CM:Reactions due to CM: mild, moderate and severe.

• Due to technique: • Incorrectly applied abdominal compression may produce

intolerable discomfort or hypotension.• Swelling and pain during injection• Extravasation of CM

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Some pathologies

• Urinary obstructions:• Calculi: most commonly form in the kidneys• Ureteral calculi may form in lower portion at VUJ and pelvic

brim.• Bladder calculi are uncommon but they are relatively larger

when present.

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Congenital or hereditary diseases:Disorder Description Radiographic findings

Renal agenesis Solitary kidney Hypertrophic single functioning kidney

Supernumerary kidney

More than two kidneys

Hypoplstic 3rd kidney, may or maynot be fused

Malrotation Abnormal position Bizzare appearance of parenchymal calyces and pelvis.

Ectopic kidney Solitary kidney 2nd kidney in another location (pelvis or thorax)

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Horse shoe kidney Lower pole- parenchymal fusion

Kidney malrotation and possible nephrogram demonstrating parenchymal fusion

Duplication More than one renal pelvis or ureter

Double renal pelvis in single kidney; two ureters exit kidney and empty into bladder.

Ureterocele Located in distal ureter (VUJ)

Round or oval dilated ureter with radiolucent halo.

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Renal agenesis

Ectopic kidney

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Ureteric calculus Rotated kidney

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Bladder diverticulum

Stag horn calculus

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Horse shoe kidney

Duplex bilateral

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Polycystic kidney disease:

Polycystic kidney disease is a disorder marked by cysts scattered throughout one or both kidneys. This disease is the most common cause of enlarged kidneys. Its cause may be genetic or congenital, depending on the type of polycystic disease. These cysts alter the appearance of the kidney and may alter renal function.

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Additional modalities

Radio nuclide imaging for renal function evaluation. Ultrasound. C.T. for investigation of trauma and renal masses. Renal Angiography. Retrograde pyelography, Urethrography. Magnetic resonance imaging.

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Lastly .….

• Contrast is what we give intravenously

• Dye is used on clothes and in cooking to change the color of things—it is not given IV to patients!

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Conclusion

• Excretion urography has long been the cornerstone of the imaging evaluation of urinary tract disease. However, other imaging modalities such as USG,CT, and MRI are being used with increasing frequency.

• The declining use of urography in clinical practice presents a challenge for instruction in urographic technique and interpretation.

• In addition, alternative modalities also have their limitations, and despite their increasing use, the ideal “global” urinary tract examination remains controversial.

• Nevertheless, urography may still be important in the diagnosis of some urinary tract disease processes.

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References:

• A guide to radiological procedure by stephen chapman, fifth edition

• Clark’s special procedure in radiography

• Dyer et.al., intravenous urography, technique and interpretation, Radiographics,2001; 799-821

• www.xray-2000.co.uk• Various other websites and ppts.

04/11/2023 59Thank you