Abstract
First Department of Surgery, Okayama University Medical School This study was made in a series of 209 cases of anal fistula. The disease was predominant in males as shown in the male to female ratio of 186: 23. The relative frequencies of the different types were: 40.2% in intersphincteric fistula; 35.9% in suprasphincteric; 16.3% in transspincteric; 5.3% in extrasphincteric; and 2.4% in superficial. The relative frequencies of the sites of the external openings of anal fistulae were 51.4% in posterior region; 17.9% in left; 14.2% in right; and 16.5% in anterior. Circumferential spreed type of infection, which is commonly known as "horseshoeing" and thought to indicate increased difficulty to treatment, was found in 52 of the 209 cases (24.9%), and in this type, the primary lesion was most frequently detected at the site of 6° (78.9%).
