Synopsis
Map a persistent anal fistula, distinguish simple from complex disease and select a treatment that controls sepsis while preserving sphincter function and verifying the outcome.
- A fistula-in-ano is a persistent communication between the anal canal and perianal skin, often recognised after recurrent swelling and discharge.
- Map the relationship to both sphincters and document baseline continence before choosing an operation; skin-opening position alone is insufficient.
- Drain an associated abscess promptly, then distinguish a temporary draining seton from a later attempt at fistula closure.
Key red flags
Recurrent or branching disease, anterior fistulas in women and pre-existing leakage require careful sphincter and continence assessment.
Diarrhoea, weight loss, proctitis, multiple openings or atypical tags may indicate Crohn-associated rather than isolated cryptoglandular disease.
An indurated, changing or persistently ulcerated lesion needs investigation for neoplasia rather than repeated assumption of benign drainage.
Investigation priorities
Define the primary tract, internal opening, secondary extensions and associated abscesses.
Management branches
A 41-year-old man has recurrent right-sided drainage after two abscess operations.
- He has preserved continence and no diarrhoea or other IBD features. MRI shows a transsphincteric tract crossing a substantial portion of the external sphincter with a small associated cavity. EUA confirms the map. The surgeon drains the cavity and places a loose draining seton rather than dividing the involved external sphincter.
- At six-week review pain and the cavity have resolved, the seton drains freely and there has been no further abscess or new leakage. This is an achieved infection-control endpoint, not yet tract eradication. After discussion of persistence and recurrence, he chooses a planned LIFT procedure for the mapped transsphincteric fistula.