A prospective audit of fistula-in-ano at St. Mark's hospital

OBJECTIVE: To conduct a prospective audit of all patients presenting with anal fistula at St. Mark's Hospital during one calendar year and to compare the presentation and outcome of this cohort with previous reports from this institution. PATIENTS AND METHODS: All patients undergoing examination under anaesthetic (EUA) for anal fistula during 1997 were studied. All fistulae were anatomically classified and operative procedures recorded. During a mean follow-up period of 14 months details of healing, recurrence and function were gathered. RESULTS: 98 patients with a mean age of 43.7 years were assessed. 86 (88%) patients had fistulae of cryptoglandular (idiopathic) origin. Fistulae were superficial in 11 (11%) patients, intersphincteric in 30 (31%) patients, trans-sphincteric in 52 (53%) patients, suprasphincteric in 3 (3%) patients and extra-sphincteric in 2 (2%) patients. 49 (50%) fistulae were classified as complex. Eradication of fistulae with preservation of function was achieved in 89 (91%) patients. Fistula recurrence occurred in 4 (4%) cases. Ten (10%) patients had some degree of incontinence, 9 (9%) of whom had undergone previous fistula surgery. Nine (9%) patients still had setons in situ at the end of the follow-up period. CONCLUSIONS: A greater proportion of difficult fistulae was seen during the year compared with previous studies from St. Mark's. Despite this a satisfactory outcome was achieved in the vast majority with a relatively low rate of disturbed function. Previous fistula surgery is a risk factor for incontinence, which can usually be managed conservatively.