12.3 Urinary System Contrast Studies

12.3 Urinary System Contrast Studies

Quick Answer: IVU/IVP (excretory urography) opacifies the urinary tract after IV iodinated contrast and timed imaging—now less common where CT urography dominates, but still conceptually examinable. Cystography and VCUG image the bladder (and urethra on voiding) with retrograde contrast. Retrograde pyelography opacifies the collecting system via cystoscopic ureteric catheterization in the OR/cysto suite. Always link iodinated contrast to renal function, hydration, allergy history, and pregnancy screening.

Blueprint Context

Gen rad urinary procedures and urinary pathology (calculi, obstruction/hydronephrosis) sit at medium to low–medium secondary weight on the CAMRT Radiological Technology blueprint, but they connect tightly to:

• RTR.4 clinical procedures (positioning, series selection, fluoro assistance)
• RTR.5 substances (iodinated contrast, routes, contraindications)
• RTR.6 image analysis (stone location, delayed excretion signs, bladder filling defects)
• Care Provider competencies (consent, monitoring, education)

Do not skip this content because “CT replaced IVP.” Entry-to-practice exams still test principles, contrast safety, and when each study is used.

Overview of Urinary Imaging Pathways

Plain-Film Context: Calculi & Obstruction Clues

Before contrast, RTRs must understand what plain images contribute:

• Many calcium-based urinary calculi are radiopaque on KUB; uric acid and some matrix stones may be lucent
• Phleboliths in the pelvis can mimic distal ureteric stones—shape and central lucency clues help image discussion
• Staghorn calculi outline the collecting system
• Indirect obstruction signs: enlarged renal outline, absent psoas margin on one side, ileus pattern—non-specific; CT/US clarify
• Hydronephrosis itself is a soft-tissue finding better shown on US/CT; IVU shows delayed nephrogram/excretion and dilated collecting systems when performed

IVU / IVP Concepts (Where Still Performed)

Intravenous urogram (IVU) and intravenous pyelogram (IVP) are often used interchangeably in clinical speech; conceptually both describe IV contrast excretion urography.

Basic sequence concepts

1. Preliminary KUB (scout) — stones, residual barium, bowel gas baseline, positioning
2. IV injection of iodinated contrast by authorized personnel per scope and policy
3. Nephrogram phase — kidneys enhance as contrast filters
4. Pyelogram/excretory phase — calyces, pelvis, ureters opacify
5. Timed overheads / fluoro spots per protocol (e.g., immediate, 5 min, 10–15 min, delayed films for obstruction)
6. Full-bladder and post-void images when ordered

RTR responsibilities (typical)

• Verify identity, order, pregnancy status, eGFR/creatinine results per protocol, allergy history, metformin and other relevant meds per site policy
• Explain procedure, warm flush sensation, and need to report itching, dyspnea, or throat tightness immediately
• Position for scouts and timed images; collimate; protect staff during any fluoro
• Recognize delayed excretion patterns that may require delayed imaging rather than ending the exam early without team input
• Document contrast type, volume, lot/expiry if required, injection time, and any reaction

Why IVU volume declined

CT urography and non-contrast CT for stones provide more information with standardized protocols. IVU may persist for select indications, resource-limited settings, or specific surgeon preferences. For the exam, know the physiology (filtration/excretion), timed imaging idea, and contrast safety, not every historic film timing table.

Cystography

Purpose: Evaluate bladder integrity (trauma/post-operative leak), diverticula, filling defects, and capacity as ordered.

Technique concepts:

• Aseptic catheterization (or use of existing catheter) per protocol—RTR assists within scope; many sites share this with nursing/urology
• Instill iodinated contrast retrograde by gravity or controlled infusion to a target volume or patient tolerance
• Multiple projections (AP, oblique, lateral as needed) and sometimes drainage images for leak
• Do not confuse bladder filling cystography with voiding study goals—orders differ

Trauma note: Suspected bladder rupture pathways often coordinate with CT cystography; plain/fluoro cystography principles still matter (adequate distension, post-drainage images for leak).

Voiding Cystourethrogram (VCUG)

Purpose: Detect vesicoureteric reflux (VUR), evaluate urethra during voiding, and assess functional emptying—especially common in pediatric urinary tract infection workups and selected adult indications.

RTR focus:

• Pediatric communication, immobilization strategies, gonadal shielding policies that do not hide critical anatomy, and dose-conscious fluoro
• Fill bladder until voiding urge or protocol volume; image during micturition
• Capture urethral lumen in appropriate projections (e.g., steep oblique/lateral concepts for male urethra)
• Grade/describe reflux only within your documentation role; radiologist interprets grades, but RTR must know reflux into ureters/kidneys is the key finding being sought
• Dignity, privacy, caregiver presence policies, and trauma-informed care

Retrograde Pyelogram Awareness

Retrograde pyelography introduces contrast directly into the ureteral orifice via cystoscopy, outlining the collecting system independent of renal function (useful when IV contrast is undesirable or non-excreting kidney needs anatomic mapping).

RTR role awareness:

• Imaging support in OR/cysto: C-arm or fixed fluoro, sterile field respect, radiation protection for team
• Scout and contrast-filled images of kidney/ureter as requested by urologist
• Contrast is not relying on glomerular filtration for opacification—distinct from IVU physiology
• Infection control and specimen handling may intersect with the case (cultures, stents)

Iodinated Contrast Prep & Renal Function Link

Urinary tract contrast studies using IV iodinated agents share safety rules with other IV contrast exams (expanded in the contrast/pharma chapter). High-yield links for this section:

Nephrogenic concerns and MRI gadolinium are separate from iodinated CT/IVU agents—do not mix them up on exam items.

Calculi & Hydronephrosis — Imaging Context for RTRs

Calculi

• Non-contrast CT is the modern gold standard for urolithiasis in many Canadian EDs; KUB may still track known opaque stones or stent position
• On IVU, a stone may appear as a filling defect or cause delayed dense nephrogram and late opacification distal to obstruction
• Ureteric stones at UVJ (vesicoureteric junction) often need inclusion of the pubic symphysis on plain films

Hydronephrosis

• Dilation of the collecting system from obstruction or reflux
• US first-line for many patients (including pregnancy)
• IVU/CT show dilated calyces/pelvis and may identify level of obstruction
• RTR image critique: asymmetric excretion, persistent nephrogram, dilated ureteral column

Pregnancy Considerations

Pregnancy intersects urinary imaging frequently (flank pain, hydronephrosis of pregnancy vs stone):

1. Screen all patients of childbearing potential per policy before ionizing radiation
2. Prefer US (and sometimes MRI) pathways when they answer the clinical question
3. If radiography/fluoro/CT is justified, optimize dose, collimate, and document consent discussions per team practice
4. Shielding of the abdomen is often not compatible with imaging the urinary tract—do not place lead over the anatomy of interest; use other optimization methods
5. VCUG and elective urography are generally deferred in pregnancy unless benefits clearly outweigh risks after specialist input

Patient Education Points

• Warm metallic taste / warm flush with IV contrast is common; distinguish from allergic symptoms
• Need to void after studies as directed; collect samples if ordered
• Hydration after IV contrast when appropriate
• After cystography/VCUG: mild dysuria can occur; report fever, severe pain, or gross hematuria beyond expected
• Pediatric caregivers: explain steps before catheter placement; allow comfort items per policy

Common Errors & Exam Traps

1. Treating IVU and retrograde pyelogram as identical routes of contrast
2. Ending an IVU early when delayed films are needed for obstruction
3. Omitting scout KUB and missing residual barium or opaque stone baseline
4. Centering that excludes UVJ on stone follow-up KUBs
5. Ignoring eGFR before IV contrast because “it’s just a urogram”
6. Assuming all urinary stones are visible on plain film
7. Balloon/catheter trauma from poor technique during cystography prep (team skill—know risks)

Pulling Chapter 12 Together

Urinary contrast studies reward RTRs who think in routes (IV vs retrograde), function vs anatomy, and safety gates (renal function, pregnancy, allergy). Master those three axes and the medium-weight urinary content becomes manageable alongside the higher-weighted chest and skeletal procedure material.