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Intravenous Urography: Technique and Normal Findings

Abbreviations and synonyms: IVP (intravenous pyelography), IVU (intravenous urography).

Indications for Intravenous Urography

The indications for intravenous urography are being pushed back by computed tomography (native or with contrast medium), which is superior in terms of sensitivity and specificity in almost every question. Without the availability of computed tomography, urography is a diagnostic option in the following situations: nephrolithiasis, gross hematuria, recurrent urinary tract infections, nephrolithiasis, urinary retention, urothelial carcinoma of bladder, upper urinary tract carcinoma, renal trauma, and urinary tract malformations.

Intravenous urography: KUB plain film (left) and KUB after 12 min (right): right distal ureteral stone (arrow) in a small ureterocele. The contrast medium is eliminated without signs of obstruction. With kind permission, Dr. R. Gumpinger, Kempten.

Examination Technique of Intravenous Urography

Premedication:

Premedication may reduce the rate of side effects of the iodinated contrast medium in certain situations: chronic kidney disease, allergic predisposition, or hyperthyroidism, see section contrast medium for the pharmacology of iodinated contrast medium. Bowel preparation before IVP delays the examination and fails to show any clear benefit in randomized trials.

Examination technique:

After emptying the bladder, the examination begins with an abdominal X-ray (KUB, plain film). contrast medium is given if good examination conditions are seen (no meteorism or contrast medium remnants of preliminary studies).

1–1.5 ml/kg contrast medium with a concentration of 300 mg/ml of iodine is given with a rapid infusion. After bolus injection, further KUB radiographs are done after 3 min (collimated to the kidneys and best done with nephrotomography), after 6 min, and after 12 min [fig. intravenous urography with distal ureteral stone]. Improved imaging of the upper urinary tract is possible with an abdominal compression of the ureters after the 6 min KUB if no obstruction is present.

Depending on the results of the 6 and 12 min imaging, further radiographs are done to e.g., evaluate hydronephrosis with insufficient contrast [fig. i.v. urography of third-grade hydronephrosis]. Collimation should be adapted to the clinical question (lower abdomen, half-sided KUB). Additional radiographs to image bladder tumors or residual urine are no longer performed due to the wide availability of ultrasound imaging.

Intravenous urography of a right-sided proximal ureteral stricture with third-grade hydronephrosis. 15 min after contrast injection (left image): contrast opacifies the dilatated calices on the right side, but not the renal pelvis or ureter. On the left side, the contrast medium has already reached the bladder as a normal finding. Additional imaging one hour after contrast injection provides clues to the localization of the ureteral stricture (right image). With kind permission, Dr. R. Gumpinger, Kempten.

Normal Findings of Intravenous Urography

Plain film KUB:

2--3 min KUB:

The nephrographic effect should be symmetric, without parenchymal defects, and the lateral convex border of the kidney is smooth. The renal length is usually 11–12 cm, and the width is around 5 cm. Parenchyma is 2–3 cm thick.

6 min KUB:

Usually the renal pelvis system and the proximal ureter are contrasted on both sides without filling defects or signs of obstruction. The anatomy of the calyces and papillae is described in fig. radiological anatomy of the renal calyces. See also section anatomy of the ureter and renal pelvis for the normal anatomy of the renal pelvis with its dendritic or ampullary norm variants.

Radiological anatomy of the renal calyces without hydronephrosis. The papillae protrude into the calyces and produce a characteristic image in the X-ray depending on the projection. In the profile, the impression of the papillae with pointed fornices is seen (left). In an oblique and orthograde projection, the papillae and fornices cause an annular shadow (center and right).

12~min KUB:

Normal findings are the complete contrasting of the ureters and the bladder without filling defects. Segmental narrowing of the ureter is caused by peristalsis. The diameter of the ureter proximal to the narrowing should be less than 8 mm. Signs of urinary obstruction are delayed contrast medium excretion, rounded calyceal fornices, calyceal "clubbing" and dilatation [fig. radiological signs of hydronephrosis], enlarged renal pelvis, and a ureter diameter >8 mm.

Radiological signs of hydronephrosis: blunted fornices and calyceal "clubbing" are signs of chronic urinary obstruction, the pointed fornices and papillar impressions disappear due to atrophy of the renal parenchyma.

Later KUB:

Later images are necessary if urinary obstruction causes delayed contrasting of the urinary tract. KUB after 1–2 hours help to find the level of obstruction and to judge the clinical significance of obstruction.

Complications of Intravenous Urography

Forniceal rupture:

Contrast medium increases diuresis and may cause a forniceal rupture [fig. forniceal rupture], most common in patients with an ureteral calculi. Forniceal rupture necessitates ureteral stenting. Intravenous urography should not be done in patients with renal colic.

Intravenous urography with forniceal rupture: 12 min film (left) and 30 min film (right): the 12~min film shows the beginning contrast medium extravasation, the 30 min film shows pronounced extravasation. With kind permission, Dr. R. Gumpinger, Kempten.

Complications due to contrast medium:

See section contrast medium.

References

  Deutsche Version: Intravenöse Urographie