Intravenous urography

Intravenous urography (IVU), also referred to as intravenous pyelography (IVP) or excretory urography (EU), is a radiographic study of the renal parenchyma, pelvicalyceal system, ureters and the urinary bladder. This exam has been largely replaced by CT urography. 

Terminology

Some prefer the term "urogram" to refer to visualisation of the kidney parenchyma, calyces, and pelvis after intravenous injection of contrast, and reserve the term "pyelogram" to retrograde studies involving the collecting system. In practice, both terms are often used interchangeably.

Procedure

Indications

• check for normal function of kidneys

• check for anatomical variants or congenital anomalies (e.g. horse-shoe kidney)

• check the course of the ureters

• detect and localise a ureteric obstruction (urolithiasis)

• assess for synchronous upper tract disease in those with bladder transitional cell carcinoma (TCC)

Patient preparation

• overnight fasting for 5 hours prior to the date of examination; a laxative may not be necessary for bowel preparation as it does not improve image quality ⁴

• on the day of the procedure take a scout/pilot film to check patient preparation and also for radiopaque calculi

• check serum creatinine level to be within the normal range (as per hospital guidelines)

• take a history of the patient for any known drug allergies followed by written informed consent for the procedure

Technique

Exposures are generally in the 65-75 kV range, mA of 600-1000, with exposure of <0.1 sec. Higher kV ranges reduce contrast of the renal parenchyma.

• IV access is required for administration of a water-soluble contrast

  • nonionic contrast is preferred

• dose will vary as per the weight of the patient; generally up to 1.5 ml/kg body weight is well tolerated by patient

• the contrast dose is usually instilled at a fast (bolus) rate ⁴ 

• an immediate AP film is taken at 10 to 14 seconds after contrast injection to visualise the renal parenchyma/outline for masses ⁴

• another AP film is taken at 5 minutes to look for any obstructions in the pelvicalyceal system ⁴

• if there is no obstruction or other contraindications, then a compression band is applied to the patient at the anterior superior iliac spines to compress the ureters at the pelvic brim and produce pelvicalyceal distensions ⁴

  • compression should not be applied if ureteral calculi, ureteral obstruction, recent surgery, nephrostomy, or abdominal aortic aneurysm is suspected ⁴

• at 10 minutes, the pelvicalyceal system should be adequately distended for imaging. If the pelvicalyceal system is not adequately distended, compression should be checked. Additional 50 ml of contrast can also be administered. After that, another AP film should be taken ⁴

• serial images are taken at 5-20 minutes for visualisation of the pelvicalyceal systems and ureters when required and with operator preference

• compression is then released and another AP film is taken to show the flow of contrast into the ureters ⁴

• additional views taken are prone and obliques for ureters

• lastly take a full bladder and post-void film. Post void film is taken to show the urinary bladder emptying. During this stage, bladder tumours, ureterovesical junction calculi, and urethral diverticulum can be seen on film ⁴

There is a wide variation in protocols. One protocol is suggested below, but additional images should usually be obtained to answer the clinical question

Films

• scout images

• nephrogram (1-2 minutes)

• early and late images of the upper collecting system (abdominal compression then applied) (5 minutes)

  Compression is contraindicated in :

  1.Renal trauma

  2.Large abdominal mass

  3.Abdominal surgery (post operative)

  4.If 5min film shows dialated calyces or if calyces and pelvis are not adequately opacified, Obstruction exists and compression band should not be applied.

• If compression is applied a film is taken after 5min i.e. at 10minutes centred on kidney to demonstrate distended collecting system and proximal ureters.

• Visualisation of ureters iwill be better in prone position as they fill better. Which is taken in 15minutes.Another method to see ureter is modified TRENDELENBERG TECHNIQUEwith 15-20 degrees head low tilt with patient in supine.

• The complete overview of the urinary tract can be evaluated in 30minutes film.

• Post void film is taken immediately for residual urine, Bladder mucosal lesion, Diverticula, Bladder tumour.

Emergency medications and emergency equipment must always be available in case the patient has a reaction to contrast.