IVP (intravenous pyelogram) or IVU (intravenous urography) is an X-ray examination in which iodinated contrast is injected into a vein and images are taken as the kidneys filter the contrast into the urine. The test can show kidney outline, collecting systems, ureters, obstruction and some stones. It is now used much less often because CT urography and ultrasound provide more detailed information in many situations, but IVU can still be encountered in older records or selected settings.

How the test is performed

After a preliminary X-ray, intravenous contrast is injected. Serial films are taken as the kidneys enhance and excrete contrast. Some protocols include compression or delayed images to outline the ureters and bladder. The duration depends on how quickly the kidneys excrete contrast and whether obstruction is suspected.

Common terms in an IVU report

Prompt bilateral nephrogram

Both kidneys take up contrast at the expected time. This is generally reassuring but does not provide a precise numerical measurement of kidney function.

Delayed nephrogram or delayed excretion

One kidney appears later or drains contrast more slowly. This can occur with obstruction or impaired renal function and should be interpreted with the ureteric findings and serum creatinine.

Hydronephrosis/hydroureter

The collecting system or ureter is dilated. The film may show the level at which contrast stops or narrows, but CT often defines the cause more accurately.

Filling defect

A non-opacified area within contrast may represent a stone, clot, tumour or artefact. Modern CT urography generally provides better characterisation.

Preparation and safety

Preparation varies by centre. Patients should disclose pregnancy, kidney disease, dehydration, diabetes medicines and any previous iodinated-contrast reaction. Modern risk assessment focuses on actual prior contrast reactions and kidney function rather than the vague label of “iodine allergy.”

Why IVU has largely been replaced

Non-contrast CT is more accurate for urinary stones, while CT urography gives better cross-sectional information about renal masses and urothelial lesions. Ultrasound avoids radiation and contrast. IVU remains historically important and can provide a useful overview of excretory anatomy, but its role is now narrower.

What an abnormal result may lead to

Further evaluation may include CT KUB for stones, CT urography for haematuria or suspected urothelial disease, ultrasound for hydronephrosis, cystoscopy for bladder pathology, or a renal scan when functional obstruction and split renal function need quantification.

IVU findings that should not be overinterpreted

Older reports may describe “pelvic fullness,” “clubbed calyces” or “non-visualised kidney.” These terms can have several causes and should not be converted directly into a modern diagnosis without current imaging. A kidney that did not opacify on an old IVU may have been obstructed, poorly functioning or simply imaged at an inadequate delay. Current ultrasound, CT and renal-function testing are usually more useful for present-day decisions.

How to read an old IVU in today’s practice

When reviewing an older IVU, ask four questions: did both kidneys form a nephrogram, did both collecting systems fill, did contrast pass down both ureters, and did the bladder fill/empty normally? Delayed or absent visualisation on one side may reflect obstruction or poor function, but old films should be interpreted cautiously if timing and renal function are unknown.

If an IVU from years ago documented a ureteric narrowing, duplex system or PUJ pattern, bring the actual films when possible. Modern CT/MRI or a renal scan may be needed to determine whether the anatomy or function has changed before making a current treatment decision.

What an IVU can and cannot tell about kidney function

Older IVU reports often describe a kidney as ‘promptly functioning’, ‘delayed’ or ‘poorly excreting’. These are useful qualitative observations, but IVU does not measure differential renal function the way a nuclear renal scan does. A delayed nephrogram can result from obstruction, impaired renal function or technical/timing factors.

If an old IVU is being used to plan modern treatment, it is often more valuable as an anatomical record of the collecting system than as a precise current function test. Ultrasound, CT, serum creatinine/eGFR and DTPA/MAG3 renography may answer different questions more reliably.

What to bring for consultation

• IVU films or digital images, not only the report.
• Recent creatinine/eGFR.
• Urine routine and culture.
• Previous ultrasound or CT.
• History of stones, surgery, ureteric stents or contrast reactions.

FAQs

Related reading

• CT Urography Report Explained
• CT KUB Report Explained
• DTPA / Renal Scan Explained
• Serum Creatinine Test Explained
• Urologist in Latur

References

• RadiologyInfo.org (ACR/RSNA). Urography. Last reviewed March 11, 2024 https://www.radiologyinfo.org/en/info/urography
• European Association of Urology. EAU Guidelines on Urolithiasis. 2026 https://uroweb.org/guidelines/urolithiasis