Anal fistulas in Crohn's disease.

Anal fistulas were recorded in 112 patients out of a series of 329 patients with Crohn's disease admitted to St Mark's Hospital for the first time between 1965 and 1976. Only 13 of 112 patients had small bowel disease alone. The remainder all had involvement of some part of the large bowel. There were 125 fistulas in the 112 patients. No treatment was attempted for 47 fistulas (38 per cent). Most patients had low fistulas which were treated by conventional techniques and healed successfully. Limited surgery was often successful in curing the symptoms of patients with more difficult fistulas. Anal lesions were the major reason for surgery in only a third of the patients who finally underwent excision of the return.