Proper VCUG Procedure
To perform a proper VCUG, use sterile catheterization technique to fill the bladder with contrast under gravity at 100 cm height, obtain fluoroscopic images during filling and at least two complete voiding cycles in the supine position, with particular attention to the posterior urethra in males during voiding. 1
Pre-Procedure Preparation
- Obtain informed consent explaining the procedure, risks (including ~2% risk of iatrogenic UTI), and benefits 1
- Consider prophylactic antibiotics in high-risk patients, though routine prophylaxis remains controversial 1
- Ensure fluoroscopy unit with recording capabilities is available 1
- Gather sterile catheterization kit, appropriately sized Foley catheter, contrast medium, sterile drapes, and gloves 1
Step-by-Step Procedure
Patient Positioning and Catheterization
- Position the patient supine on the fluoroscopy table 1
- Insert an appropriately sized Foley catheter into the bladder using strict sterile technique 1
Contrast Administration
- Fill the bladder with contrast under gravity at approximately 100 cm above the table (not under pressure) 1
- This gravity-based filling mimics physiologic bladder filling and reduces risk of iatrogenic reflux
Image Acquisition Protocol
- Perform at least 2 complete filling-voiding cycles - this is critical as 21% of vesicoureteral reflux (VUR) is only detected after the initial negative cycle, with the majority being clinically significant dilating reflux 2
- Obtain images during active voiding to assess bladder emptying, urethral anatomy, and reflux during micturition 1
- For male patients, pay particular attention to visualizing the posterior urethra during voiding to detect posterior urethral valves (PUV) 1
Age-Specific Considerations
- Younger children (<1 year) are more likely to benefit from cyclic studies - 74.1% of children under 1 year should undergo cyclic evaluation compared to only 6.9% of children over 5 years 2
- In newborns with antenatal hydronephrosis, wait at least 48-72 hours after birth before performing VCUG 1
Critical Pitfalls to Avoid
- Inadequate visualization of the male posterior urethra may miss PUV - ensure proper imaging during active voiding 1
- Performing only a single voiding cycle will miss 21% of VUR cases, particularly high-grade reflux 2
- Performing VCUG too early in newborns (before 48-72 hours) may yield inaccurate results 1
- Excessive radiation exposure - cyclic studies actually result in lower median radiation doses (2.15 vs 4.41 microGy m²) when performed properly 2
Radiation Dose Optimization
- Cyclic VCUG protocols paradoxically result in lower radiation exposure than single-cycle studies when performed efficiently 2
- Consider simplified protocols using only full-bladder and post-void images for follow-up studies, which maintain 87-100% sensitivity and specificity while reducing radiation 3