How to perform a Voiding Cystourethrogram (VCUG)

How to Perform a Voiding Cystourethrogram (VCUG)

A voiding cystourethrogram (VCUG) is a fluoroscopic technique that focuses on imaging the bladder and urethra during filling and voiding, primarily used to detect vesicoureteral reflux (VUR) and urethral abnormalities. The procedure should be performed following a standardized protocol to ensure accurate diagnosis and minimize patient discomfort.

Preparation

• Obtain informed consent explaining the procedure, risks, and benefits 1
• Consider prophylactic antibiotics in patients at high risk for infection, though routine prophylaxis is controversial 1
• Take a scout image before contrast administration to identify any radiopaque calculi or abnormalities 2

Equipment and Materials

• Fluoroscopy unit with recording capabilities 1
• Sterile catheterization kit 1
• Appropriate-sized Foley catheter 1
• Contrast medium (water-soluble, iodinated) 1
• Sterile drapes and gloves 1

Procedure Steps

1. Patient Positioning and Preparation

• Position the patient supine on the fluoroscopy table 1
• Use aseptic technique throughout the procedure 1
• Cleanse the perineal area with antiseptic solution 1

2. Catheterization

• Insert an appropriately sized Foley catheter into the bladder using sterile technique 1
• Secure the catheter to prevent displacement 1

3. Contrast Administration

• Connect the catheter to the contrast medium 1
• Fill the bladder with contrast under gravity at a height of approximately 100 cm above the table 1
• Fill until one of the following occurs:
  • Patient expresses discomfort 1
  • Maximum predicted bladder capacity is reached (calculated as [age in years + 2] × 30 mL) 3
  • Contrast begins to reflux into ureters 1
  • Contrast leaks around the catheter 1

4. Imaging During Filling

• Obtain images of the bladder during filling to assess for:
  • Early reflux 1
  • Bladder contour and capacity 1
  • Bladder wall thickness or trabeculation 1
• Document the volume at which reflux occurs, if present 2

5. Voiding Phase

• Position the patient upright (sitting on a radiolucent commode) for the voiding phase 1
• For infants who cannot sit, maintain the supine position 1
• Remove the catheter when the bladder is adequately filled 1
• Obtain images during voiding to assess:
  • Bladder emptying 1
  • Urethral anatomy 1
  • Reflux during voiding 1
  • Urethral narrowing or dilatation 1

6. Post-Void Assessment

• Obtain a post-void image to assess residual volume 1, 2
• Calculate the post-void residual volume 2

Documentation and Reporting

• Record the following information in the report:
  • Total volume instilled 3, 2
  • Presence or absence of VUR and its grade if present 1, 2
  • Volume at which reflux occurs 2
  • Whether reflux occurs during filling or voiding 1
  • Bladder morphology (trabeculation, diverticula) 1
  • Urethral anatomy and any abnormalities 1
  • Post-void residual volume 2

Special Considerations

For Male Patients

• Pay special attention to the posterior urethra to detect potential posterior urethral valves (PUV) 1
• Consider using silodosin (8 mg) prior to the procedure in adult males to enhance visualization of the posterior urethra if difficulty opening the bladder neck is anticipated 4

For Pediatric Patients

• Use appropriate distraction techniques and consider sedation for younger children 3
• For infants with antenatal hydronephrosis, VCUG is indicated if renal and bladder ultrasonography reveals hydronephrosis, scarring, or findings suggesting high-grade VUR or obstructive uropathy 1
• Consider cyclic filling and emptying for better detection of reflux in children 2

Pitfalls to Avoid

• Failing to document the volume at which reflux occurs, which is important for predicting spontaneous resolution 2
• Not reporting whether reflux occurs during filling or voiding phase, which has prognostic implications 2
• Inadequate visualization of the male posterior urethra, which may miss PUV 1
• Performing VCUG too early in newborns with antenatal hydronephrosis (should wait at least 48-72 hours after birth) 1
• Risk of iatrogenic UTI (reported in about 2% of VCUGs performed for evaluation of antenatal hydronephrosis) 1