Rectovaginal Fistula
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Direct answer
Passage of flatus or faeces through the vagina defines a rectovaginal fistula, an abnormal communication between the rectum or anus and the vagina that brings foul discharge, recurrent urinary and vaginal infections and profound social embarrassment. In India the commonest cause remains obstructed labour — prolonged second stage with pressure necrosis between the fetal head and pubic symphysis, the same mechanism as vesicovaginal fistula — while Crohn disease, radiation injury, malignancy, operative trauma (haemorrhoidectomy, hysterectomy, episiotomy repair) and tuberculosis account for the rest. Low fistulae are repaired per anum using a transanal advancement flap with sphincter repair; high fistulae demand a transabdominal approach with resection and coloanal anastomosis; complex, recurrent or actively inflamed fistulae need stool diversion first. Timing matters — obstetric fistulae are usually repaired after three to six months of tissue recovery unless the fistula is small and fresh.
What you must remember
- Height defines the operation: low fistulae (anal canal/low rectum, vaginal introitus-level) — transanal advancement flap, sphincteroplasty, or transperineal repair with Martius fat-pad interposition; high fistulae (upper rectum, posterior vaginal fornix) — abdominal resection with colorectal or coloanal anastomosis, usually with a defunctioning stoma.
- Indian context: obstructed labour from inadequate obstetric care remains a leading cause, alongside Crohn disease and postoperative injury; a rural woman reporting faecal passage per vaginam months after a difficult home delivery carries the classic history.
- Simple bedside tests: methylene blue or betadine instilled in the rectum with a tampon in the vagina (tampon test), a vaginal swab showing faeculent staining, and contrast vaginography for elusive high tracts; glucose testing of discharge helps in suspected vesicovaginal overlap.
- Define anatomy before surgery: examination under anaesthesia, endoanal ultrasound or pelvic MRI mapping the tract, sphincter integrity, and exclusion of malignancy, active Crohn disease, tuberculosis and radiation injury — repairing an irradiated or inflamed tract fails predictably.
- Treat the cause first: Crohn fistulae need biological or immunomodulator control, and tuberculous fistulae antitubercular therapy, before or instead of scalpel; malignancy-related fistulae are oncology problems.
- Adjuvants and salvage: faecal diversion (loop ileostomy or colostomy) for high, recurrent, or septic fistulae; fibrin glue and fistula plugs have poor results in rectovaginal fistulae; Martius interposition and gracilis muscle flaps salvage recurrent low fistulae; ultimate options include proctectomy with permanent stoma in refractory radiation disease.
- Set expectations: primary repair success for simple fistulae is around 70-90 percent, falling steeply with Crohn disease, radiation and previous repairs — hence the principle of the best chance at the first operation.
A typical exam case
A 24-year-old primigravida from a rural area delivered a stillborn baby after 30 hours of obstructed labour at home. Ten days later she began passing flatus and liquid stool through the vagina. Examination under anaesthesia three months later shows a 1.5-centimetre fistula at the rectovaginal septum just above the anal sphincter complex, with intact sphincters and healthy surrounding tissue — a low fistula. Her nutrition and anaemia are corrected, bowel prepared, and she undergoes a transanal advancement flap with sphincteroplasty for an associated torn sphincter, without a diverting stoma. She heals. Contrast this with a 45-year-old on pelvic radiotherapy for cervical cancer with a high fistula and indurated irradiated tissue: no flap will survive there — she needs a diverting colostomy for symptom control and, in selected fit patients, a major resection with omental interposition or permanent diversion.
How the exam frames it
Expect the obstetric-history stem — difficult labour, home delivery, stillbirth, then faecal leakage per vaginam — with the question being cause (pressure necrosis of the rectovaginal septum) or the timing of repair (wait three to six months unless a fresh small fistula is recognised immediately after delivery, when prompt repair can succeed). The second theme is matching operation to height: advancement flap for low, transabdominal resection for high — options mixing these up are the distractors. Third, the Crohn angle: any stem mentioning perianal disease, diarrhoea and a rectovaginal fistula in a young woman expects medical optimization first, never an immediate flap.
Frequently asked questions
Which is the commonest cause of rectovaginal fistula in India?
Prolonged obstructed labour causing pressure necrosis of the rectovaginal septum, the same injury that produces vesicovaginal fistula; Crohn disease and surgical or radiation injury follow.
How is the fistula demonstrated when the tract is not visible?
Examination under anaesthesia, the methylene blue tampon test, endoanal ultrasound or pelvic MRI, and vaginography for suspected high tracts.
What operation suits a low rectovaginal fistula?
Transanal endorectal advancement flap, usually with sphincter repair, or a transperineal repair with Martius fat-pad interposition for recurrent cases.
When should repair be delayed after obstetric injury?
For about three to six months, allowing oedema, infection and necrosis to settle and tissues to become supple — except a fresh, clean fistula recognised immediately postpartum, which can be repaired primarily.
What role does a stoma play in management?
Temporary diversion protects high, recurrent, irradiated or septic fistulae during repair; permanent diversion is the fallback for incurable radiation or malignancy-related fistulae.