Studies of the natural history of perianal Crohn's disease reveal that it is generally characterized by a benign course, however, the symptoms may on occasion be disabling.
Most abscesses are simple and most fistulas are of the low, simple type.
Anorectal excision is more often indicated for control of severe proctitis or proctocolitis than for perianal lesions. When perianal lesions are the indication for proctectomy or permanent fecal diversion, it is usually because of high fistulas, strictures and anovaginal fistulas. There is evidence that perianal lesions may heal if active disease elsewhere is controlled, either medically or surgically, but this has not been a consistent experience. The success rate of anal operations has been correlated with the absence of rectal disease and quiescent disease elsewhere in the gut, but these are not consistent observations. Metronidazole has demonstrated effectiveness in controlling perianal and colonic Crohn's disease.