Excretory urography — also called intravenous urography (IVU) or intravenous pyelography (IVP) — uses serial projection radiographs, sometimes with fluoroscopy, after intravenous iodinated contrast to depict renal excretion and the collecting systems. Its present role is limited: ACR Appropriateness Criteria generally favor risk-stratified CT urography for appropriate hematuria evaluation, noncontrast CT for most nonpregnant adults with acute stone suspicion, and ultrasound or MR urography in selected scenarios. IVU may still be performed where cross-sectional imaging is unavailable or when a radiologist chooses it for a focused question.
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.
IVP and IVU are commonly used interchangeably. IVU or excretory urography is the more descriptive term because the examination evaluates more than the renal pelvis.
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.
Overlying stool can reduce projection-image visibility, but cathartic preparation is not universally required and routine fasting is not required solely for modern intravascular iodinated contrast. Follow the radiologist-approved local protocol and the patient's clinical needs:
Before any contrast administration, the technologist must perform a thorough screening. This includes:
Recognize a severe allergic-like reaction (for example, respiratory distress from bronchospasm or laryngeal edema, or hypotension with anaphylaxis). Stop the injection, activate the facility emergency response, assess airway/breathing/circulation, obtain vital signs, provide oxygen and positioning appropriate to the patient's condition, and bring the emergency cart/AED. Under the authorized protocol, adult IM epinephrine 0.3 mg (0.3 mL of 1 mg/mL [1:1,000]) into the anterolateral thigh is first-line for anaphylaxis and may be repeated every 5-15 minutes; dosing/routes differ for children and for IV use. Do not delay escalation to trained resuscitation personnel.
A standard radiographic/fluoroscopic room is used for IVU. The equipment requirements include:
Modern nonionic low-osmolality iodinated contrast is generally used because it causes fewer adverse events than older high-osmolality agents. Contrast concentration, volume, injection duration, cannula size, and site are protocol- and patient-specific; verify the prescribed agent/dose and injector limits rather than treating 50-100 mL, 30-60 seconds, or a particular gauge as universal. Confirm a suitable, functioning IV and observe the site during injection.
An IVU uses a protocol-selected timed series. The examples below are conventional teaching times, not universal orders: timing and projections must be adapted to the injection, renal function, clinical question, observed excretion, and radiologist direction.
Full abdomen KUB before contrast. Evaluates bowel preparation, identifies calcifications (stones, phleboliths), and provides baseline anatomy.
Often 30-60 seconds after injection. Shows renal parenchymal opacification and permits comparison of renal size, contour, and symmetry. Abnormal timing or density is nonspecific.
Often demonstrates the collecting systems. Review it for excretion and obstruction before any optional compression; actual timing varies.
If specifically ordered and no contraindication or obstruction is evident, compression can distend the collecting systems. Prone or oblique images may instead improve segmental ureter visualization.
After full release, an immediate abdomen image may demonstrate ureteral drainage and bladder filling; peristalsis often makes opacification segmental.
If indicated, an image after voiding assesses residual contrast and drainage. A radiograph cannot accurately quantify post-void urine volume; ultrasound or catheterization is used when a numerical residual is needed.
Scout (Preliminary) KUB: When included, a precontrast abdomen image evaluates coverage and calcifications before they can be obscured by contrast. It should include both kidneys and the bladder/pubic symphysis. A calcification's disappearance or nonvisualization later does not by itself prove its origin; localization uses its course, morphology, multiple projections, and—when needed—cross-sectional imaging.
Early Nephrogram (often 30-60 seconds): An early image captures renal parenchymal opacification. Compare size, contour, onset, density, and symmetry. A delayed, asymmetric, patchy, or persistent nephrogram is nonspecific and can reflect altered perfusion, obstruction, or parenchymal dysfunction; it is not diagnostic of renal artery stenosis and must be interpreted with other imaging and clinical data.
Early Excretory Film (often about 5 minutes): The calyces, infundibula, and renal pelvis are commonly visible, but excretion varies. This image should be reviewed before compression. Nonvisualization has a broad differential—including delayed function/obstruction, technical timing, prior nephrectomy, or congenital absence—and requires radiologist-directed evaluation rather than assumption.
10-15 Minute Film (Optional Compression): If the radiologist-approved protocol calls for compression and the preliminary/early images show no obstruction or contraindication, temporary compression may distend the collecting systems. Do not apply or continue it merely to reach a clock time; monitor the patient and release immediately for significant pain, distress, or concern.
Post-Release Ureter Image: If compression was used, it is fully released before an immediate abdomen image. Ureteral peristalsis commonly causes segmental nonopacification, so a single image need not show both ureters continuously. Fluoroscopic spot, prone, oblique, or delayed images may be selected by the radiologist; persistent nonvisualization is not by itself proof of a stone.
Post-Void Film: When clinically useful, an image after voiding assesses residual contrast in the bladder and upper-tract drainage. It does not directly measure residual urine; obtain bladder ultrasound or catheter measurement when an accurate post-void residual volume is required. Retained contrast or upper-tract dilation is interpreted with the complete examination and clinical findings.
With suspected obstruction or delayed excretion, do not apply compression. Notify the radiologist, who may choose additional delayed images or a different modality. There is no universal serum-creatinine cutoff such as 2.0 mg/dL: use AKI status and eGFR, the clinical need, alternatives, and the radiologist-approved contrast policy.
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 optional, not an automatic timed step. Apply it only when ordered and only after early images have been reviewed to exclude obstruction and other contraindications. Use the minimum pressure and duration needed, continuously assess the patient, and release it fully before ureter/bladder imaging—or immediately for significant pain or distress.
Compression must not be used in the following situations:
When compression is contraindicated, the radiologist may use prone, oblique, fluoroscopic spot, or appropriately delayed images to improve segmental visualization. Prone positioning can help contrast reach portions of the ureters; it should not be described as a dependable way to “slow drainage,” and intentionally overfilling the bladder is not a substitute for safe compression.
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 (often 30-60 s) | Renal parenchymal opacification | Usually relatively homogeneous and symmetric; apparent renal length varies with body size, projection, and magnification | Compare onset, density, size, and contour; abnormalities are nonspecific and collecting-system contrast may already be present |
| 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 (optional compression) | Distended pelvicalyceal system | Calyces and renal pelvis may be better distended | Use only after obstruction/contraindications are excluded; filling defects require further characterization |
| Post-Release | Ureters and bladder | Variable, often segmental ureteral opacification because of peristalsis; expected narrow regions include the UPJ, iliac-vessel/pelvic-brim crossing, and UVJ | Assess course, caliber, drainage, and persistent defects across available images; continuous bilateral opacification is not required on one image |
| Post-Void | Residual bladder contrast and upper-tract drainage | Variable residual contrast | Qualitative drainage assessment only; IVU does not accurately quantify residual urine or diagnose vesicoureteral reflux (use ultrasound/catheter measurement or voiding cystourethrography as appropriate) |
The IVU is useful for diagnosing a range of urinary tract conditions. Radiographic signs to recognize include:
A radiopaque calculus may be seen on the scout, while a calculus in an opacified collecting system may produce a filling defect or obstruction. Contrast outlining a calcification along the ureter supports a ureteric location, but overlap on a projection image is not definitive. A central lucency favors a phlebolith but is neither required nor perfectly specific. Noncontrast CT is generally preferred for acute stone suspicion in nonpregnant adults because IVU signs such as delayed nephrogram, dilation, or nonopacification are indirect and nonspecific.
Dilatation of the renal pelvis and calyces (hydronephrosis) and ureter (hydroureter) may appear as calyceal blunting, pelvic ballooning, and ureteral dilation. Causes include UPJ obstruction, stones, strictures, reflux, and extrinsic compression, but dilation does not always equal current obstruction. Ultrasound, CT, MRU, or diuretic renal scintigraphy is usually used to define cause and functional significance; IVU is poor at measuring cortical thinning.
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.
IVU may show a renal contour abnormality, collecting-system displacement, or filling defect, but it cannot reliably distinguish a simple cyst from a solid renal neoplasm or characterize enhancement. An indeterminate renal mass requires appropriate multiphase CT, MRI, or ultrasound characterization; a collecting-system filling defect also has multiple causes and needs further evaluation.
Three classically narrow regions are (1) the ureteropelvic junction (UPJ), (2) the iliac-vessel/pelvic-brim crossing, and (3) the ureterovesical junction (UVJ). Stone passage depends on size, location, anatomy, and clinical status; do not promise a fixed passage percentage. Infection with obstruction, worsening renal function, uncontrolled symptoms, or a solitary/at-risk kidney requires urgent clinical escalation.
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) | Risk-appropriate hematuria/urothelial evaluation; selected collecting-system questions | Cross-sectional renal and urothelial assessment, extrarenal findings, multiplanar reconstructions, no compression | Ionizing radiation and IV iodinated contrast; protocol and dose vary. CTU is not the routine stone-colic protocol and is not automatically appropriate for every hematuria patient |
| CT Abdomen/Pelvis (Noncontrast) | Most nonpregnant adults with acute flank pain and suspected stone | Fast, no IV contrast, depicts most stones and secondary signs; reduced-dose protocols can be used when appropriate | Ionizing radiation; limited excretory/urothelial assessment; very small stones and uncommon drug/matrix stones may be occult |
| 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) | Selected congenital, obstructive, pediatric, or iodinated-contrast/radiation-avoidance questions | No ionizing radiation; heavily T2-weighted MRU can depict fluid-filled tracts without contrast; contrast-enhanced MRU can add functional information | Longer, motion-sensitive, less available; MRI safety screening required. In pregnancy, prefer noncontrast MRI when it can answer the question; gadolinium is not routine and requires specific risk-benefit justification |
| Retrograde Pyelography | Urologist-directed detailed collecting-system evaluation or intervention | Direct opacification; can accompany stenting, ureteroscopy, or biopsy | Invasive cystoscopic procedure with infection/trauma risks; anesthesia needs vary. Systemic allergic-like reactions are uncommon but not impossible because absorption/intravasation can occur |
Despite these alternatives, the IVU remains valuable for:
There is no single “standard” IVU effective dose: it varies substantially with patient size, exposure count, equipment, collimation, fluoroscopy, and technique. Record and review available dose indicators and optimize each examination under ALARA rather than quoting a fixed 3-5 mSv or assuming IVU is always lower dose than CT.
Dose reduction strategies include:
Extravasation can occur with hand or power injection even after an IV appears patent. Check for local swelling, pain, altered perfusion, sensation, and range of motion. If suspected, stop injection immediately, summon the appropriate clinician, examine and document the site, elevate the limb, and use cold or warm compresses according to local policy; give clear return precautions and observe until symptoms are stable or improving. Escalate urgently for severe/progressive pain or swelling, decreased capillary refill/perfusion, sensory change, blistering/ulceration, or reduced motion. Surgical consultation should be based on signs and symptoms—not an arbitrary volume threshold. Follow local policy on whether/when to remove the cannula. Review our detailed guide on contrast extravasation management for complete protocols.
After the IVU is complete, the technologist has several responsibilities:
Use a radiologist-approved, patient-specific protocol. IVU is now a selected examination rather than the default hematuria or renal-colic test. Do not routinely fast, dehydrate, stop metformin, apply compression, or use contact shielding. Screen for prior same-class contrast reactions, AKI/eGFR risk, pregnancy, and procedure-specific hazards; never compress a suspected obstruction. Stop contrast for a reaction or extravasation, assess promptly, and activate the appropriate emergency pathway.
IVP (intravenous pyelogram) and IVU (intravenous urogram) are commonly used interchangeably for excretory urography after intravenous iodinated contrast. IVU/excretory urography better describes evaluation of the urinary tract rather than only the renal pelvis.
The nephrogram is renal parenchymal opacification after intravenous contrast. An early image is commonly obtained at about 30-60 seconds, but timing varies with injection and protocol. Asymmetric, delayed, or persistent opacification is nonspecific and must be interpreted with the full study and clinical context.
No. Routine fasting is not required solely for modern intravascular iodinated contrast, and laxative or enema preparation is not universal. A site may use limited dietary or bowel preparation to reduce overlying stool for projection radiography, but it should follow the local protocol and avoid dehydration; individual aspiration, fluid-restriction, and cathartic risks must be considered.
When specifically requested and safe, external lower-abdominal compression temporarily retards ureteral drainage and distends the pelvicalyceal systems. It is used only after images exclude obstruction and other contraindications, released before ureter/bladder images, and released immediately if significant pain or distress occurs.
There is no blanket rule that a prior severe iodinated-contrast reaction or eGFR below 30 is an absolute contraindication. A prior severe reaction to the same contrast class is a relative contraindication requiring radiologist-led risk-benefit review and alternatives when feasible. Acute kidney injury or eGFR below 30 also requires individualized assessment and usually prophylaxis when contrast is necessary. Metformin itself is not a contrast contraindication; management depends on AKI/eGFR. Pregnancy requires justification and optimization of ionizing radiation, not automatic testing or automatic refusal.
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.