GU Studies
Intravenous Urography (IVU)
Anatomy
Indications, Contraindications, and Patient Preparation
Indications
- Abdominal or pelvic masses.
- Urolithiasis (renal or ureteral stones).
- Kidney trauma.
- Hematuria (blood in urine).
- Hypertension related to renal function.
- Renal failure (evaluate cause).
- Recurrent urinary tract infections.
Contraindications
- Hypersensitivity to iodinated contrast.
- Anuria (no urine production).
- Severe renal disease or failure (high BUN/creatinine).
- Diabetes, especially on metformin (Glucophage) → risk of lactic acidosis; discontinue 48 hrs post-exam.
- Multiple myeloma.
- Pheochromocytoma (rare adrenal tumor).
- Relative: pregnancy (use ultrasound instead if possible).
Patient Preparation
- Bowel cleansing: low-residue diet 1–2 days prior, laxative afternoon before exam.
- NPO: nothing after midnight before exam.
- Laxative contraindications: do not give if patient has gross bleeding, severe diarrhea, obstruction, or acute appendicitis.
- Voiding: patient empties bladder prior to procedure.
Procedure Overview
Intravenous Urography (IVU) — also known as excretory urography or intravenous pyelogram (IVP) — evaluates both structure and function of the urinary system by tracking the filtration and excretion of iodinated IV contrast.
The exam begins with a pre-contrast (scout) KUB, followed by a series of time-stamped images after injection.
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Nephrogram or nephrotomograms are taken immediately post-injection to visualize renal parenchyma.
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5–20-minute images show progressive opacification of calyces, renal pelvis, ureters, and bladder.
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Oblique views display kidneys in profile and separate ureters from the spine.
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A post-void image assesses residual urine and kidney mobility (nephroptosis).
Prone positioning can substitute for ureteral compression when compression is contraindicated (stones, trauma, aneurysm, abdominal mass, recent surgery, suprapubic catheter).
Patients must be NPO for 8 hours, screened for renal function and contrast contraindications, and monitored during and after injection for adverse reactions.
Use precise collimation and labeling (include time markers, body position, and projection) to maintain reproducibility and reduce dose.
Summary Table for Clinical Workflow
| Step | Timing / Technique | Purpose |
|---|---|---|
| Scout KUB | Before contrast | Baseline anatomy, calcifications |
| Nephrogram / Tomogram | 0–1 min | Parenchymal phase, renal function |
| Timed KUBs (5, 10, 15, 20 min) | Sequential | Track excretion and ureteral patency |
| Obliques (10–15 min) | During filling | Profile kidneys, open ureterovesical junctions |
| Post-Void Film | After voiding | Evaluate residual urine, nephroptosi |
Contrast Media & Safety
Contrast Type:
Water-soluble iodinated contrast — non-ionic preferred for reduced reaction risk.
Pre-Exam Screening:
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Allergies: Iodine, seafood, shellfish, x-ray “dye.”
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Asthma, hay fever, prior contrast reaction.
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Medical history: Diabetes (esp. on metformin), renal disease, multiple myeloma, pheochromocytoma.
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Check BUN and creatinine before injection; ensure normal urine output.
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Pregnancy screening for women of childbearing age.
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Catheterized patients: clamp Foley before injection.
Metformin Precaution:
Hold for 48 hours post-contrast, restart only if renal function remains stable.
Technologist Key Points:
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Document screening responses before injection.
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Do not proceed without physician clearance if contraindications exist.
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Stay with the patient during and immediately after contrast administration.
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Keep emergency equipment accessible; never leave a symptomatic patient unattended.
Contrast Reaction Quick Reference
| Severity | Examples | Response |
|---|---|---|
| Mild (Common, Usually Self-Limiting) | Warmth/flushing, metallic taste, mild nausea, limited hives, sneezing | Reassure and monitor; usually no treatment required. |
| Moderate (Potentially Concerning) | Diffuse hives, vomiting, facial/laryngeal edema, wheezing | Stop infusion, notify radiologist, provide O₂, prepare IV antihistamines or bronchodilators. |
| Severe (Life-Threatening) | Shock, severe bronchospasm, arrhythmia, unresponsiveness | Call code; begin CPR as needed; administer epinephrine/IV fluids per protocol. |
Post-Reaction Documentation:
Record onset, symptoms, treatment, and outcome in the patient chart.
Routine Projections (ARRT Required)
Scout & Post-Contrast KUB (AP Abdomen)
CR Location & Positioning
- SID: 40 inches
- Patient position: Supine; midsagittal plane (MSP) centered to table.
- Adjustments: Arms out of field; knees supported for comfort.
- CR: Perpendicular to IR at level of iliac crests (L4–L5).
- Patient instructions: Suspend respiration at end of expiration; remain still.
- Exposure: 14 × 17 inches (35 × 43 cm) lengthwise; standard abdominal technique.
Evaluation Criteria
- Coverage (what anatomy must be included and how you verify it’s complete): Diaphragms through symphysis pubis; urinary tract visualized throughout.
- Rotation checks (how symmetry or alignment tells you if positioning is correct): Iliac wings symmetrical; spinous processes midline.
- Motion checks (how sharpness confirms patient cooperation/exposure timing): Sharp renal and psoas margins; crisp bowel gas outlines.
- Technique checks (what contrast, density, soft tissue visibility, and artifacts to look for): Proper contrast density; visible psoas shadows and renal outlines.
- Clinical aim (when applicable, e.g., reflux, obstruction, displacement, etc.): Establish baseline anatomy and assess for calculi or masses before contrast administration.
Nephrogram / Nephrotomogram (Immediate Post-Injection)
CR Location & Positioning
- SID: 40 inches
- Patient position: Supine.
- Adjustments: Center midway between xiphoid process and iliac crests (kidney level); set tomography fulcrum per protocol.
- CR: Perpendicular to kidney region.
- Patient instructions: Suspend respiration; hold still.
- Exposure: Collimate to upper abdomen (kidney region); tomography parameters per protocol.
Evaluation Criteria
- Coverage: Both kidneys included; cortical and medullary zones visible.
- Motion checks: Sharp parenchymal detail without blur.
- Technique checks: Appropriate exposure to visualize contrast concentration without over-penetration.
- Clinical aim: Demonstrate parenchymal phase (nephrogram) showing renal function and structure.
5–15 Minute KUBs (Supine and Prone)
CR Location & Positioning
- SID: 40 inches
- Patient position: Supine (routine) and prone (to improve ureter filling).
- Adjustments: Center IR at iliac crests; arms out of field.
- CR: Perpendicular at iliac crests.
- Patient instructions: Suspend respiration; remain still.
- Exposure: 14 × 17 inches; visible time marker on each film.
Evaluation Criteria
- Coverage: Entire urinary system from kidneys to bladder.
- Rotation checks: Symmetric iliac wings; spine aligned with pubic symphysis.
- Technique checks: Progressive contrast filling from calyces to bladder.
- Clinical aim: Assess excretion pattern and ureteral patency.
- Note: Prone images improve visualization of ureters by separating them from the spine.
Posterior Obliques (RPO / LPO, 10–15 min)
CR Location & Positioning
- SID: 40 inches
- Patient position: Supine, rotated 30° into RPO or LPO.
- Adjustments: Flex knee of elevated side; spine centered; arms clear of field.
- CR: Perpendicular to IR, centered at iliac crests, 2 inches lateral to MSP on elevated side.
- Patient instructions: Suspend respiration after expiration.
- Exposure: 14 × 17 inches lengthwise.
Evaluation Criteria
- Coverage: Kidneys, ureters, and bladder visualized.
- Rotation checks: Elevated kidney elongated (parallel to IR); down-side kidney foreshortened (perpendicular to IR).
- Technique checks: Down-side ureter free of spine superimposition.
- Clinical aim: Demonstrate ureterovesical junctions and differentiate kidney orientation.
AP Bladder (Timed or Delayed)
CR Location & Positioning
- SID: 40 inches
- Patient position: Supine, MSP aligned to IR.
- Adjustments: Center 2 inches above pubic symphysis; mild caudad angle may clear symphysis.
- CR: Perpendicular (or 10–15° caudad).
- Patient instructions: Suspend respiration.
- Exposure: 10 × 12 inches (24 × 30 cm), crosswise or lengthwise per habitus.
Evaluation Criteria
- Coverage: Entire bladder and distal ureters visible.
- Rotation checks: Pelvis symmetric; coccyx aligned with symphysis.
- Technique checks: Adequate contrast to demonstrate bladder contour.
- Clinical aim: Evaluate bladder filling, vesicoureteral junctions, and distal ureters.
Post-Void KUB
CR Location & Positioning
- SID: 40 inches
- Patient position: Upright preferred (to assess nephroptosis and residual urine).
- Adjustments: IR centered at iliac crests.
- CR: Perpendicular to iliac crests.
- Patient instructions: Suspend respiration.
- Exposure: 14 × 17 inches lengthwise; label POST-VOID.
Evaluation Criteria
- Coverage: Entire urinary tract, including bladder base.
- Rotation checks: Symmetric iliac wings; spine aligned with pubic symphysis.
- Technique checks: Progressive contrast filling from calyces to bladder.
- Clinical aim: Assess bladder emptying efficiency and kidney mobility.
Supplemental Projections
Lateral or Decubitus
CR Location & Positioning
- SID: 40 inches
- Patient position: Lateral recumbent (for localization) or dorsal decubitus (for horizontal beam).
- Adjustments: MCP centered to IR; arms raised; knees slightly flexed.
- CR: Perpendicular at level of iliac crests.
- Patient instructions: Suspend respiration after expiration.
- Exposure: 14 × 17 inches lengthwise.
Evaluation Criteria
- Coverage: Entire urinary tract in profile.
- Rotation checks: Hips and femurs superimposed; posterior bladder wall single line.
- Clinical aim: Distinguish anterior/posterior displacement of kidneys, localize calculi, or evaluate fluid levels.
Hows & Whys of Intravenous Urography
Anatomy
- How do the kidneys filter contrast medium?
Contrast is excreted by glomerular filtration, allowing visualization of the renal parenchyma and collecting system. - How does nephroptosis appear on IVU?
The kidney descends more than 2 inches between supine and upright films, indicating abnormal mobility. - How can obstruction be identified?
Delayed contrast filling or absence of contrast distal to a point suggests ureteral obstruction or stone.
Positioning
- Why is IVU considered a functional study?
It demonstrates both anatomy and renal function by capturing timed contrast excretion through the urinary system. - Why are nephrotomograms taken immediately after injection?
They show the parenchymal (nephrogram) phase before contrast drains into the collecting system, revealing renal architecture and function. - Why are prone films sometimes obtained?
Prone positioning separates ureters from the spine, improving visualization of the mid-ureter. - Why are oblique projections performed?
They display the kidneys and ureters without overlap, showing the elevated kidney in profile and the dependent ureter unobscured. - Why is a post-void film essential?
It assesses residual urine volume, possible obstruction, reflux, or bladder dysfunction.
Technique & Image Evaluation
- How do you confirm proper kidney visualization?
Both kidneys should appear symmetrically with sharp margins and visible contrast in calyces and pelvis. - How do you detect abnormal renal function?
Compare contrast density between kidneys and across time-marked films; delayed or faint opacification indicates impaired excretion. - How can you evaluate ureteral patency?
Continuous contrast flow from pelvis to bladder across sequential films confirms open ureters. - How is motion prevented during timed imaging?
Suspend respiration on expiration and support knees for comfort to reduce voluntary movement. - How is patient safety ensured during injection?
Monitor the patient continuously during and after contrast administration for adverse reactions.
Clinical Applications
- Why must diabetic patients on metformin withhold medication after IV contrast?
To prevent lactic acidosis, a rare but serious reaction that can occur if renal function is impaired post-contrast. - Why is renal function testing required before IVU?
Elevated BUN or creatinine levels indicate reduced filtration and increased risk of contrast nephropathy. - Why are compression devices used selectively?
They delay ureteral emptying to enhance pelvicalyceal filling but are contraindicated with stones, trauma, aneurysm, or recent surgery. - Why should technologists never leave the patient immediately after contrast injection?
Most serious contrast reactions occur within the first 5 minutes of administration and require rapid response. - Why is non-ionic contrast preferred?
It has lower osmolality and significantly reduces the risk of allergic or chemotoxic reactions.
