However, the medication is required for prolonged periods and side effects limit its use. The main determinant of whether or not anal Crohn's disease is treated operatively is the severity of symptoms. Lesions producing minimal symptoms should not be treated by operation. Other factors which must be considered in selecting treatment options include the presence of undrained pus, rectal involvement, the type or complexity of fistulous disease, and to a lesser extent, the activity of proximal gastrointestinal disease. Local operations for perianal Crohn's disease should be limited to drainage of pus, laying open of symptomatic low fistulas and gentle dilatation of short, low strictures.
Operations are necessary in a small percentage of patients.
A loop ileostomy should be placed prior to an attempt at local repair of an anovaginal fistula. Fecal diversion reduces anal and perianal inflammation, allowing a repair to be performed in healthier tissues. Diversion does not always produce a melting away of perianal Crohn's and some lesions may even progress. However, most patients will have significant symptomatic improvement following diversion. There is little chance of success if the local repair is performed in the presence of intense proctitis.