Intravenous urography (IVU) is a radiographic study of the renal parenchyma, pelvicalyceal system, ureters and urinary bladder using intravenous contrast medium. This exam has been largely replaced by CT urography. 

Terminology

The term "urography" refers to evaluation of the entire urinary tract, ie. kidneys, pelvicalyceal systems, ureters and bladder. Intravenous pyelography (IVP) or excretory urography (EU) are commonly used as alternative but less accurate terms. Some reserve the term "pyelography" to refer to retrograde opacification of the collecting system.

Indications

IVU is rarely performed if CT is available. However if a CT IVU demonstrates delayed excretion due to obstruction, a delayed radiograph following CT IVU can identify the site of obstruction.

IVU can provide important information:

• ureteric obstruction: severity, site and cause e.g. urolithiasis

• synchronous or metachronous upper tract tumour: detailed evaluation of pelvicalyceal and ureteral morphology in patients with bladder transitional cell carcinoma (TCC)

• papillary necrosis

• anatomical variants such as horseshoe kidney

• the course of the ureters

• renal function

Patient preparation

• fasting for 5 hours prior to the examination is preferred; laxatives to reduce faecal loading do not improve image quality ⁴

• check eGFR

• check for allergies and contrast medium reactions and obtain written informed consent according to hospital guidelines

• emergency medications and equipment must be available to treat clinically significant contrast medium reactions

Technique

Exposures in the 65-75 kV range optimise radiographic contrast, mA of 600-1000 and exposure time < 0.1 second.

There are various IVU techniques ⁴. 18 or 19G gauge IV access is required for bolus injection of a water-soluble iodinated contrast agent; nonionic contrast medium has a better safety profile. A dose up to 1.5 ml/kg body weight is well tolerated.

For suspected ureteric obstruction the following radiographs will suffice:

• control AP radiograph of the kidneys, ureters and bladder to show calculi which can be obscured by contrast medium

• 3 minute post injection AP radiograph of the kidneys to show contrast medium beginning to appear in the pelvicalyceal systems. Unilateral absent excretion indicates obstruction. Cortical and medullary nephrogram is normally well seen at 3 minutes but attenuation may be reduced on the obstructed side

• 10 minute full-length AP radiograph, optional obliques

• full-length post-micturition radiograph to confirm ureteric obstruction and delineate the lower ureter which can be obscured by contrast medium in the bladder

• if the obstruction is severe and the ureter is insufficiently opacified, perform delayed full-length radiographs at 1 hour +/- 24 hours

High-grade obstruction can significantly delay excretion. The nephrogram on the obstructed side will be delayed, and will persist and increase in attenuation. If the site of obstruction is not delineated at 1 hour, then a 24-hour delayed radiograph is indicated.

Contrast medium is heavier than urine and this property can be used to advantage. An erect full-length radiograph will demonstrate a full ureter to the point of obstruction. If the patient cannot stand, lie them prone to demonstrate the mid ureter and then supine to show the distal ureter.

The technique for synchronous or metachronous upper tract urothelial tumours includes detailed views of the pelvicalyceal systems and ureters.

• 5 minute AP radiograph of the kidneys then apply a lower abdominal compression band to distend the upper tracts

• AP and both oblique radiographs of the kidneys at 10 minutes

• full length AP radiograph and both obliques on compression release

• prone views are optional to show the mid ureters

• multiple images help overcome the problem of non-visualisation of ureteric segments due to normal peristalsis

• AP full-length post void view

Compression is contraindicated in:

• renal trauma

• large abdominal mass

• abdominal surgery (post operative)

• abdominal aortic aneurysm