VESICOVAGINAL FISTULA

Vesicovaginal fistula (VVF)
Fistula: an abnormal communication between two epithelial surfaces, in the case of a VVF between bladder and vagina. In 10% there is a coexisting ureterovaginal fistula.

Aetiology
In developing countries, the majority are associated with obstructed or prolonged childbirth, causing tissue pressure necrosis between vagina and bladder. More rarely caused by schistosomiasis. In developed countries, 75% follow hysterectomy (0.1 - 0.2% risk). Also other pelvic surgery (e.g. bowel resection); radiotherapy; pessaries; advanced pelvic malignancy (cervical carcinoma); pelvic endometriosis; inflammatory bowel disease; trauma (pelvic fracture); childbirth (5%); low oestrogen states; infection (urinary TB); congenital abnormalities.

Symptoms
Immediate or delayed onset of urinary leakage from the vagina post-operatively; prolonged bowel ileus (due to some leak of urine into peritoneal cavity as well as through vagina); suprapubic pain or flank pain.

Examination
- Vaginal examination may demonstrate the VVF, if large (the examining finger can reach inside the bladder).
- 3-swab test oral phenazopyridine turns urine orange. After 1 h, place 3 swabs into the vagina and instil methylene blue into the bladder. If the proximal swab turns blue it indicates VVF; if it is orange, it suggests ureterovaginal fistula.
- Cystogram (or voiding cystourethrography, VCUG). Best test for identifying fistula.
- Fistula track may be seen at cystoscopy and can help in determining its proximity to the ureteric orifices. Biopsy the tract if history of malignancy.
- IVU and/or bilateral ureterograms to assess ureteral involvement.

Management
Conservative methods, including urethral catheterization combined with anticholinergics and antibiotics, for small, uncomplicated VVF. Alternatively, de-epithelization of the tract can be attempted with silver nitrate, electrocoagulation, or curettage with metal screws. If there is a coexisting ureterovaginal fistula, a ureteric stent or catheter can be sited. Most cases require surgery.

Surgery
Early repair (within 2 - 3 weeks) is advocated in simple cases but, traditionally, surgery is delayed 3 - 6 months. The transvaginal approach has success rates of 82 - 100%. The fistula tract is closed with 2 layers of sutures, and covered by an anterior vaginal wall flap. Additionally, interpositional tissue grafts may be mobilized between the bladder and vagina (Martius fat pad graft from labia majora; peritoneal flap; gracilis flap). The abdominal approach is reserved for complex cases. The bladder is bisected to the level of the fistula tract, which is then completely excised (85 - 90% success). The bladder is closed and an interpositional omentum graft created. In complex cases, urinary diversion procedures may be needed.