Best Test to Diagnose Vaginal Fistula After Total Robotic Hysterectomy
MRI pelvis with IV contrast is the best test to diagnose a vaginal fistula after a total robotic hysterectomy due to its superior contrast resolution for evaluating fistulous tracts and ability to detect active inflammation. 1, 2
Diagnostic Approach for Vaginal Fistulas
First-Line Imaging Tests
- MRI pelvis with IV contrast: Provides superior soft-tissue contrast resolution for evaluating fistulous tracts and is particularly useful for detecting active inflammation in fistulous tracts and abscesses 1, 2
- CT with IV contrast: Alternative with comparable diagnostic utility (sensitivity of 76.5% for fistula detection and 94.1% for defining etiology) 3, 1
- Fluoroscopic vaginography: High sensitivity (79%) and positive predictive value (100%) for identifying fistulous tracts 3, 2
MRI Protocol Considerations
- IV gadolinium contrast is essential for visualizing active inflammation in fistulous tracts 2
- Phased array body coil should be used for optimal imaging 3
- T2-weighted sequences help identify fluid-filled tracts, while contrast-enhanced sequences can visualize collapsed tracts that do not contain fluid 3
CT Imaging Approach
- Water-soluble contrast should be placed in the suspected organ (bladder, rectum) to opacify fistulous tracts 3, 4
- For suspected vesicovaginal fistulas, CT cystography can be performed 3
- For suspected rectovaginal fistulas, rectal contrast may help delineate perforation or leak 3
- Water-soluble contrast is preferred over barium to avoid complications if spillage occurs 3
Fluoroscopic Vaginography Technique
- Large-gauge Foley catheter (26-gauge with 30-mL balloon) is placed in vaginal lumen 3
- Balloon is inflated to prevent contrast spillage 3
- Water-soluble contrast is injected under fluoroscopic guidance 3
- Spot radiographs are obtained in multiple views (anteroposterior, oblique, lateral) 3
- Can also be performed with CT for improved anatomical detail 3
Caveats and Pitfalls
- Foley catheter balloon may occlude low fistulas during vaginography, leading to false negatives 3
- Complex fistulas with multiple branches may not be completely filled during vaginography 3
- Contrast enema has low sensitivity for rectovaginal fistulas (7.7-34% depending on location) 3
- Early post-operative diagnosis is crucial to minimize patient morbidity and allow for prompt repair 5
- Methylene blue dye test can provide quick outpatient diagnosis but may miss small or complex fistulas 5
Anatomical Considerations
- Determine if the fistula is high (rectovaginal) or low (anovaginal) based on symptoms and imaging findings 2
- Document the position of internal opening, track characteristics, and vaginal opening location 2
- Report the size of any associated abscess and note signs of inflammation 2
- Consider complex fistulas that may have multiple openings or be complicated by abscess 1