Excretory urography — also called intravenous urography (IVU) or intravenous pyelography (IVP) — is a fluoroscopic and radiographic procedure that images the urinary tract after the intravenous administration of iodinated contrast medium. Despite the increasing use of CT urography, the IVU remains a valuable diagnostic tool for evaluating the kidneys, ureters, and bladder, especially in settings where CT is not readily available or for specific indications such as hematuria workup, suspected ureteric calculi, and post-operative assessment of the urinary tract.
For radiologic technology students, understanding the IVU procedure is essential for both the ARRT registry and clinical practice. This article provides a comprehensive walkthrough — from patient preparation and contrast injection through the complete sequence of radiographs, compression techniques, post-procedure care, and alternative imaging modalities.
Although IVP (intravenous pyelogram) and IVU (intravenous urogram) are often used interchangeably, IVU is the more accurate term. Pyelography refers specifically to imaging of the renal pelvis, while urography encompasses the entire urinary tract — kidneys, ureters, and bladder. The ARRT and most modern textbooks prefer the term excretory urography or IVU.
Proper patient preparation is critical for obtaining diagnostic-quality images during an IVU. The technologist is responsible for verifying preparation, screening for contraindications, and ensuring informed consent.
A clean bowel is essential because overlying stool and gas obscure the kidneys, ureters, and bladder. Standard preparation typically includes:
Before any contrast administration, the technologist must perform a thorough screening. This includes:
Know your facility's protocol for contrast reactions. The ARRT expects you to recognize signs of anaphylaxis (urticaria, bronchospasm, hypotension, laryngeal edema) and initiate emergency response — stop contrast, call for help, position the patient supine, and administer oxygen. Epinephrine (1:1000, 0.3-0.5 mg IM) is the first-line treatment for severe reactions.
A standard radiographic/fluoroscopic room is used for IVU. The equipment requirements include:
Non-ionic, low-osmolality iodinated contrast (e.g., iopamidol, iohexol, ioversol) is preferred due to lower risk of adverse reactions. Typical dose: 300-600 mgI/kg (approximately 50-100 mL of 300 mgI/mL contrast for an average adult). The contrast is injected intravenously over 30-60 seconds through an 18-22 gauge IV cannula, typically placed in an antecubital vein.
The hallmark of a properly performed IVU is a timed series of radiographs. Each image in the sequence has a specific purpose and timing window. The ARRT registry frequently tests knowledge of this sequence.
Full abdomen KUB before contrast. Evaluates bowel preparation, identifies calcifications (stones, phleboliths), and provides baseline anatomy.
30-60 seconds post-injection. Shows opacification of renal parenchyma. Evaluates renal size, contour, and perfusion. A delayed or absent nephrogram may indicate obstruction or reduced function.
Contrast fills the collecting system — calyces, infundibula, and renal pelvis. With compression, calyces appear distended. Without compression, contrast may begin draining into the ureters.
With compression applied at 5 min, this film shows maximally distended pelvicalyceal systems. Alternatively, a prone view can help visualize the ureters as contrast flows anteriorly.
After releasing compression, contrast flows freely into the ureters and bladder. A KUB or large-format film is taken immediately after release.
After the patient voids, a final KUB evaluates residual bladder volume and confirms complete drainage of the upper tracts. A "post-void residual" > 50-100 mL is abnormal.
Scout (Preliminary) KUB: The first image is a full abdomen radiograph (kidneys, ureters, bladder) taken before contrast injection. This film serves multiple purposes: verifying bowel preparation adequacy, identifying pre-existing calcifications that could be mistaken for contrast in later images, and assessing technical factors. The scout film must include the kidneys superiorly and the pubic symphysis inferiorly. Any calcification seen on the scout but not on post-contrast films is likely a phlebolith or gallstone rather than a ureteric calculus.
Nephrogram Phase (30-60 seconds): Taken immediately after the completion of contrast injection, this radiograph captures the nephrographic phase when contrast medium is within the renal tubules and the renal parenchyma is opacified. A homogeneous, dense nephrogram bilaterally indicates good renal perfusion and function. A delayed or patchy nephrogram may indicate renal artery stenosis, acute obstruction, or chronic renal disease. Clinical tip: If the scout film revealed a potential renal stone, the nephrogram phase helps confirm its location within the collecting system versus the renal parenchyma.
5-Minute Film: By 5 minutes post-injection, contrast has been filtered by the glomeruli and excreted into the collecting system. The calyces, infundibula, and renal pelvis become visible. This film is ideally taken with ureteric compression applied to distend the pelvicalyceal system. If only one kidney is opacified, consider renal agenesis, prior nephrectomy, or severe unilateral obstruction.
10-15 Minute Film (With Compression): With continued compression, contrast accumulates in the renal collecting system, providing detailed evaluation of the calyceal anatomy — each minor calyx should be sharply defined. This film is optimal for detecting papillary necrosis, calyceal diverticula, filling defects (stones, tumors), and hydronephrosis. The compression also slows contrast flow into the ureters, allowing better visualization of the upper tracts.
Post-Release (Full Ureter) Film: After the 10- or 15-minute compression film, the compression paddles are released, and a supine abdominal film is taken immediately. Contrast rushes distally, filling the ureters from the ureteropelvic junction to the ureterovesical junction. The entire course of each ureter should be visible. If a segment of the ureter is not opacified, it may be due to peristalsis (transient) or an obstructing stone. Oblique films can help distinguish between the two. A prone film taken at this time can also improve visualization of the anteriorly located ureters.
Post-Void Film: After the patient empties their bladder, a final KUB is taken. This evaluates bladder emptying and confirms complete drainage of the upper tracts. The normal post-void residual should be less than 50 mL. An enlarged post-void residual with bilateral hydroureter suggests bladder outlet obstruction (e.g., prostatic enlargement in males).
In patients with renal insufficiency or obstruction, contrast excretion may be delayed. In such cases, delayed films at 30 minutes, 1 hour, or even 24 hours may be necessary to visualize the collecting system. Always communicate with the radiologist if the standard sequence does not produce adequate opacification. Remember: a patient with a serum creatinine > 2.0 mg/dL should generally not receive IV contrast — check the most recent lab values before proceeding.
Ureteric compression is a specialized technique used to improve visualization of the renal pelvicalyceal system during IVU. Understanding when and how to apply compression is an ARRT registry topic.
The compression device consists of two radiolucent foam or inflatable paddles mounted on a belt assembly. The paddles are positioned over the lower abdomen, at the level of the pelvic brim (approximately at the level of the anterior superior iliac spines), where the ureters cross the pelvic brim. When inflated or tightened, the paddles compress the ureters against the psoas muscles and sacral promontory, temporarily occluding urine flow.
Compression is applied after the 5-minute film when contrast is seen in the collecting system. It is maintained for 5-10 minutes while the contrast accumulates and distends the calyces and pelvis. The compression should be firm but comfortable — the patient should not be in significant pain.
Compression must not be used in the following situations:
When compression is contraindicated, alternative techniques include prone positioning (which uses gravity to slow contrast drainage) or taking earlier films with a full bladder (a distended bladder can slow ureteric drainage).
To evaluate an IVU properly, the technologist must recognize normal anatomy and common variants. The following table summarizes key structures visible on each phase of the study.
| Phase / Film | Structures Visualized | Normal Appearance | Evaluation Criteria |
|---|---|---|---|
| Scout KUB | Renal outlines, psoas margins, bony pelvis, soft tissues | Smooth renal contours (L kidney slightly higher than R); psoas margins symmetric; no abnormal calcifications | Bowel preparation adequate; no overlying artifact; proper collimation from diaphragm to pubic symphysis |
| Nephrogram (30-60 s) | Renal parenchyma (nephrons and tubules) | Homogeneous, dense bilateral opacification; kidneys measure ~11-14 cm in length | Symmetric density; sharp renal outlines; no filling defects in parenchyma; visualized before contrast enters collecting system |
| 5-min (Early Pyelogram) | Calyces (major and minor), infundibula, renal pelvis | Sharp, cupped minor calyces; funnel-shaped infundibula; renal pelvis may be intrarenal or extrarenal | All calyceal groups opacified (upper, middle, lower); no blunting or clubbing of calyces; symmetrical filling |
| 10-15 min (Compression) | Distended pelvicalyceal system | Well-distended calyces with sharp fornices; renal pelvis filled | No filling defects (stones, tumors, blood clots); ureters not yet opacified (compression working) |
| Post-Release | Full ureters, bladder | Ureters 3-5 mm diameter; three physiologic narrowings: UPJ, pelvic brim crossing, UVJ; bladder dome opacified | Entire ureter visible from UPJ to UVJ; no strictures or filling defects; contrast flows freely into bladder |
| Post-Void | Bladder (residual), upper tract drainage | Minimal residual contrast in bladder (< 50 mL); no contrast retained in calyces or ureters | Near-complete drainage; normal residual volume; assess for vesicoureteral reflux if performed |
The IVU is useful for diagnosing a range of urinary tract conditions. Radiographic signs to recognize include:
Renal or ureteric calculi appear as filling defects within the contrast-opacified collecting system. A stone seen on the scout film that is surrounded by contrast on post-contrast films is a ureteric calculus. If a calcific density is seen on the scout but is outside the opacified ureter, it is likely a phlebolith (calcified pelvic vein). Key differentiating features: phleboliths often have a lucent center (laminated appearance), while calculi are more homogeneously dense. On IVU, a stone causes a filling defect with contrast above it (column of contrast proximal to the obstruction) and a delayed nephrogram on the affected side.
Dilatation of the renal pelvis and calyces (hydronephrosis) and ureter (hydroureter) appears as blunting of the calyceal fornices, ballooning of the renal pelvis, and a dilated, tortuous ureter. Causes include ureteropelvic junction (UPJ) obstruction, ureteric stones, ureteric strictures, and extrinsic compression. The degree of hydronephrosis is graded from mild (blunting of calyces only) to severe (massive dilatation with thinning of renal cortex).
Most commonly associated with diabetes mellitus, sickle cell disease, and analgesic nephropathy. The characteristic IVU finding is a contrast-filled cavity within a renal papilla. The sloughed papilla may detach completely, creating a "ring shadow" — contrast surrounding a filling defect. Early changes appear as small irregular collections of contrast at the calyceal fornices.
On the nephrogram phase, a renal mass appears as a filling defect or contour abnormality within the opacified renal parenchyma. Simple renal cysts appear as well-circumscribed, lucent defects with thin walls. Renal cell carcinomas appear as irregular, solid masses with variable contrast enhancement. In advanced cases, collecting system invasion produces irregular filling defects in the calyces or pelvis.
A classic ARRT question asks where ureteric calculi most commonly lodge. The answer is the three physiological narrowings of the ureter: (1) the ureteropelvic junction (UPJ), (2) where the ureter crosses the pelvic brim over the iliac vessels, and (3) the ureterovesical junction (UVJ). The UVJ is the narrowest point and the most common site for stone impaction. About 90% of stones <5 mm pass spontaneously, while larger stones often require intervention (lithotripsy, ureteroscopy).
While the IVU remains a useful study, newer imaging modalities have replaced it for many indications. Understanding when each modality is appropriate is expected for the ARRT exam.
| Modality | Best Indications | Advantages Over IVU | Limitations |
|---|---|---|---|
| CT Urography (CTU) | Hematuria evaluation, stone disease, renal mass characterization, trauma | Higher sensitivity for small stones (>98%); detects non-urinary tract pathology; 3D reconstructions; no compression needed; faster | Higher radiation dose (~10-15 mSv vs ~3 mSv for IVU); requires IV contrast with similar renal function precautions |
| CT KUB (Non-Contrast) | Suspected ureteric colic / acute renal stone | No contrast needed; very fast (30 seconds); excellent for stone detection regardless of size or composition; detects secondary signs (hydronephrosis, perinephric stranding) | Limited functional information; cannot evaluate renal perfusion or excretion; higher radiation |
| Renal Ultrasound | Hydronephrosis assessment, renal cyst evaluation, pediatric imaging, pregnancy | No radiation; no contrast needed; excellent for distinguishing solid from cystic masses; portable; low cost | Operator-dependent; limited visualization of ureters; less sensitive for small stones; limited functional assessment |
| MR Urography (MRU) | Pediatric patients, pregnancy, contraindication to iodinated contrast, congenital anomalies | No ionizing radiation; excellent soft-tissue detail; can evaluate renal parenchyma without iodinated contrast; provides functional information with contrast-enhanced sequences | Longer exam time; motion-sensitive; expensive; limited availability; contraindicated in patients with certain implants/claustrophobia |
| Retrograde Pyelography | Detailed evaluation of ureteric anatomy, patients who cannot receive IV contrast | Excellent ureteric detail; no systemic contrast reaction risk; can be combined with therapeutic intervention (stent placement, stone extraction) | Invasive (cystoscopy required); requires anesthesia/sedation; risks include infection, ureteric perforation |
Despite these alternatives, the IVU remains valuable for:
A standard IVU delivers an effective dose of approximately 3-5 mSv (depending on the number of films and patient size). The technologist should optimize technique to minimize dose while maintaining diagnostic image quality.
Dose reduction strategies include:
IV contrast is administered through a power injector at pressures that can cause extravasation if the IV is not properly placed. Always confirm patency by aspirating blood return and flushing with saline before connecting the contrast tubing. If extravasation occurs (the patient reports burning, stinging, or swelling at the IV site), stop the injection immediately, remove the IV, elevate the extremity, apply warm or cold compresses (check your facility protocol), and document the event. For large-volume extravasations involving high-osmolality agents, consult the radiologist — compartment syndrome is a rare but serious complication. Review our detailed guide on contrast extravasation management for complete protocols.
After the IVU is complete, the technologist has several responsibilities:
Try these ARRT-style multiple choice questions based on this article. Click an option to check your answer — correct answers turn green, wrong ones turn red.