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GU Studies

Cystourethrography (Voiding Cystourethrogram -VCUG)

Anatomy

Students should be able to identify the following structures on radiographic images:

Ureters, Bladder (Apex, Base, Neck, Trigone), Ureterovesical junction (UVJ), Urethra,  Prostate (male)

Indications, Contraindications, and Patient Preparation

Indications

  • Vesicoureteral reflux (especially in pediatrics).
  • Recurrent urinary tract infections.
  • Evaluation of urethra during voiding (strictures, trauma, post-surgical assessment).
  • Incontinence or abnormal voiding patterns.

Contraindications

  • Relative: allergy to iodinated contrast.
  • Active urinary tract infection (procedure may worsen infection).
  • Severe urethral trauma (consult physician before catheterization).

Patient Preparation

  • No dietary prep required.
  • Patient should empty bladder before catheterization.
  • Procedure explained carefully (especially to children and parents, since voiding during imaging can be stressful).
  • Catheterization performed under aseptic technique.

Procedure Overview

Cystourethrography (VCUG) evaluates the bladder and urethra during filling and voiding using retrograde instillation of dilute iodinated contrast through a sterile catheter. The contrast flows into the bladder by gravity only, with the bag no more than 24 inches above the bladder to prevent overdistension.

Dynamic fluoroscopy records the filling and voiding phases to assess urethral patency, reflux, and sphincter function.

Special procedural variations include:

  • Metallic Bead-Chain Technique (Female Stress Incontinence Studies):
    A small chain is inserted through the urethra with its proximal end in the bladder and distal end taped to the thigh. AP and lateral upright projections are taken at rest and during the Valsalva maneuver to evaluate the posterior urethrovesical angle, urethral axis, and bladder floor mobility.

  • Upright Voiding Studies:
    Used to simulate normal voiding mechanics.
    Men: Usually imaged in RPO position using a urinal.
    Women: Typically imaged in upright AP, with optional lateral view for urethral motion analysis.


Routine Projections (ARRT Required)

AP Projection (Female VCUG)

CR Location & Positioning

  • SID: 40 inches
  • Patient position: Supine or semi-upright AP; legs slightly apart, arms at sides.
  • Adjustments: Center IR to superior border of the pubic symphysis.
  • CR: Perpendicular to IR, entering 2 inches (5 cm) above pubic symphysis; 5° caudal angulation may project pubic bones below bladder neck.
  • Patient instructions: Remain still during filling; void when instructed. Suspend respiration at end of expiration.
  • Exposure: Routine urinary contrast technique.

Evaluation Criteria

  • Coverage (what anatomy must be included and how you verify it’s complete): Bladder, urethra, and distal ureters visualized during filling and voiding.
  • Rotation checks (how symmetry or alignment tells you if positioning is correct): Symmetric pelvis; pubic bones at midline.
  • Motion checks (how sharpness confirms patient cooperation/exposure timing): Sharp bladder and urethral margins without motion blur.
  • Technique checks (what contrast, density, soft tissue visibility, and artifacts to look for): Adequate contrast density in bladder and urethra; no cutoff at symphysis.
  • Clinical aim (when applicable, e.g., reflux, obstruction, displacement, etc.): Evaluate bladder neck, urethra, and reflux during voiding.

AP Oblique Projection (Male VCUG – RPO)

CR Location & Positioning

  • SID: 40 inches
  • Patient position: Supine, rotated 30–40° into RPO.
  • Adjustments: Position penis obliquely across thigh to prevent superimposition. Extend and abduct elevated thigh to avoid overlap.
  • CR: Perpendicular to IR, centered 2 inches above pubic symphysis and 2 inches medial to elevated ASIS.
  • Patient instructions: Remain still during filling; void on command. Suspend respiration at end of expiration.
  • Exposure: Routine urinary contrast technique.

Evaluation Criteria

  • Coverage: Entire urethra demonstrated from bladder neck to external meatus.
  • Rotation checks: Pubic rami projected lateral to urethral course; urethra unobscured.
  • Motion checks: Sharp margins of bladder and urethra without motion.
  • Technique checks: Adequate density and contrast through bladder and urethra.
  • Clinical aim: Demonstrate full urethral course and evaluate reflux or obstruction during micturition.

Supplemental Projections

Lateral Projection (Either Sex)

CR Location & Positioning

  • SID: 40 inches
  • Patient position: True lateral recumbent.
  • Adjustments: Flex knees slightly for stability; raise or flex elbows at right angle to clear pelvis. Ensure hips and femurs are superimposed.
  • CR: Perpendicular to IR, centered 2 inches above pubic symphysis at midcoronal plane.
  • Patient instructions: Remain still during voiding if possible. Suspend respiration at end of expiration.
  • Exposure: Routine urinary contrast technique.

Evaluation Criteria

  • Coverage: Bladder and urethra in profile, distal urethra and external sphincter visualized.
  • Rotation checks: Hips and femurs superimposed; pelvis true lateral.
  • Motion checks: Sharp bladder outline and urethral course.
  • Technique checks: Sufficient contrast opacification; no cutoff from soft tissue overlap.
  • Clinical aim: Detect urethral fistulae, diverticula, or abnormal urethral course.

Hows & Whys of Cystourethrography

Anatomy

  • How does the male urethra differ from the female urethra?
    The male urethra is longer (approximately 17–20 cm) and has three segments (prostatic, membranous, and spongy), while the female urethra is short and straight (approximately 3–4 cm).
  • How does the trigone differ from the rest of the bladder?
    It remains fixed and non-distensible during bladder filling, serving as a stable landmark for the ureteral orifices.
  • How can prostate enlargement appear radiographically?
    As an elevated or smooth filling defect at the base of the bladder due to compression by the enlarged gland.

Positioning

  • Why is the male urethra imaged in an oblique position (RPO)?
    The oblique angle elongates the urethra and prevents superimposition of the thigh and pubic rami over its course.
  • Why is the female urethra imaged AP?
    The short, nearly vertical urethra can be evaluated directly in the AP projection without obstruction by bony structures.
  • Why might a lateral projection be added?
    It provides a profile view of the urethra and bladder, useful for detecting fistulae or diverticula.
  • Why must the contrast bag not exceed 24 inches above the bladder?
    This limits hydrostatic pressure and prevents overdistension or rupture during filling.
  • Why is gravity filling preferred to manual injection?
    Gravity ensures controlled bladder filling and prevents trauma to the urethra or bladder wall.

Technique & Image Evaluation

  • How do you confirm adequate visualization of the urethra?
    The entire urethral course—from bladder neck to external meatus—must be filled with contrast and unobscured by bone or soft tissue.
  • How can you detect vesicoureteral reflux?
    Reflux is present when contrast is seen ascending the ureters during filling or voiding phases.
  • How do you assess for urethral stricture?
    A localized narrowing or abrupt cutoff in contrast flow indicates a stricture site.
  • How do you verify the study captured the voiding phase?
    Images or fluoroscopic loops must demonstrate active contrast flow through the urethra during micturition.
  • How can motion be minimized during the voiding phase?
    Encourage the patient to void smoothly and remain as still as possible; short exposure times freeze motion.

Clinical Applications

  • Why is cystourethrography considered a functional study?
    It evaluates both anatomy and function of the bladder and urethra during voiding, not just at rest.
  • Why is VCUG especially common in children?
    It is the gold-standard test for diagnosing vesicoureteral reflux, a frequent cause of recurrent UTIs in pediatrics.
  • Why is iodinated contrast used instead of barium?
    Iodinated contrast is water-soluble and safe if extravasated; barium could cause inflammation or obstruction in the urinary tract.
  • Why must pediatric patients be carefully coached?
    Voiding on command in a medical setting can be difficult or intimidating; reassurance and comfort improve cooperation and image quality.
  • Why are upright or stress views sometimes performed?
    To evaluate stress incontinence or bladder floor descent, often using bead-chain or upright voiding techniques.

 

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Radiographic Procedures Review Guide Copyright © 2025 by Carla M. Allen and Taylor M. Otto is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License, except where otherwise noted.