What is the preferred imaging study, X-ray cystogram (X-ray) or CT cystogram (Computed Tomography), for confirming healing after Vesicovaginal Fistula (VVF) repair?

CT Cystogram is Preferred for Confirming Healing After VVF Repair

CT cystography should be used over conventional X-ray cystography for confirming healing after vesicovaginal fistula repair, as it has supplanted fluoroscopic cystography at most institutions and provides superior diagnostic accuracy for detecting bladder fistulas and leaks. 1

Rationale for CT Cystography Superiority

Diagnostic Performance

• CT cystography has become the primary imaging modality for bladder fistulas and leaks, with the American College of Radiology explicitly stating that it has replaced fluoroscopic cystography for evaluation of bladder injuries and fistulous communications 1
• CT with bladder contrast (either retrograde cystogram or antegrade with delayed imaging after IV contrast) demonstrates high sensitivity (76.5%) for fistula detection and can identify persistent fistulous tracts with enhancing tissue 2
• The technique allows visualization of the fistulous tract, associated bladder wall thickening, and any residual communication that would indicate incomplete healing 3, 2

Technical Advantages Over Fluoroscopy

• CT provides superior anatomic detail and can detect complications that fluoroscopy may miss, including small residual tracts, associated abscesses, or other pelvic pathology 1
• CT cystography offers better characterization of the size and location of any persistent fistula for potential re-intervention planning 3
• The cross-sectional imaging capability of CT allows assessment of surrounding structures and complications beyond what fluoroscopic cystography can demonstrate 1

Optimal Imaging Protocol

CT Cystography Technique

• Water-soluble contrast should be instilled into the bladder (retrograde CT cystogram) to opacify any persistent fistulous tract 2
• Alternatively, delayed imaging after IV contrast administration can be performed (antegrade approach) 2
• The bladder should be adequately distended during imaging to maximize detection of small persistent communications 2

Timing of Confirmation Study

• Healing confirmation should be performed at 3 weeks post-repair when the urethral catheter is typically removed, using cystography to document tract closure before catheter removal 4
• If clinical concern persists despite negative initial imaging, repeat assessment may be warranted 4

Alternative Imaging Considerations

When MRI May Be Preferred

• MRI pelvis with IV contrast provides superior soft tissue resolution and is equally sensitive to CT for evaluating vesicovaginal fistulae (per ACR guidelines) 1
• MRI should be considered if there is concern for complex fistula anatomy, multiple tracts, or need to assess for active inflammation in the healing tract 2
• MRI is particularly useful when radiation exposure is a concern in younger patients requiring multiple follow-up studies 1

Role of Conventional Fluoroscopic Cystography

• Fluoroscopic cystography is "generally not useful" according to ACR guidelines and has been supplanted by CT at most institutions 1
• The only potential advantage is lower radiation dose, but this is outweighed by inferior diagnostic accuracy 1
• Conventional X-ray cystography should only be used if CT is unavailable or contraindicated 1

Clinical Pitfalls to Avoid

• Do not rely on clinical examination alone to confirm healing, as studies demonstrate imaging is superior to clinical evaluation for detecting residual fistulous tracts 1
• Ensure adequate bladder distention during cystography, as inadequate filling can result in false-negative studies 2
• Do not use barium-based contrast agents; water-soluble contrast is mandatory for cystography 1
• If CT cystography is equivocal, consider supplementing with MRI pelvis rather than repeating fluoroscopic studies 2