THE CLASSIFICATION OF ANO-RECTAL FISTULAE

Abstract

Summary 1. A series of 111 cases of anal fistula has been studied. 2. There were 3 cases of submucous anal fistula. Each of these cases possessed a track which passed deep to smooth muscle. This muscle may be muscularis mucosae alone, but part or whole of the internal sphincter may be included. 3. The majority of anal fistulae were classified as peri-anal anal fistulae because they appeared to be the sequel of a perianal abscess. There were 81 cases; in 11 no internal opening could be found, whilst in 3 there was no external opening. 4. In 24 cases, the fistula appeared to involve primarily the ischiorectal fossa and, in most, to originate in the middle line posteriorly, very close to the ano-rectal ring. The fistulous track lay in the deep post-anal space and usually involved one or both ischiorectal fossae. An external opening was absent in two patients. Secondary tracks may lie in the peri-anal space and, in two, secondary tracks passed through the iliococcygeus portion of the levator ani muscle. 5. In 3 cases the fistula coursed from an external opening in the skin to an internal opening in the rectum. The pathology of these was uncertain, but they did not appear to be a sequel of ischiorectal infection. 6. It is believed that the term “ano-rectal fistula” should not be applied to any one type of fistula, but should be used in the widest sense of the term to include all fistulae in the region. Classification should be revised to incorporate modern views on the anatomy of the region.