FISTULA-IN-ANO - A PROSPECTIVE-STUDY OF 107 PATIENTS

Background: While the majority of fistulas-in-ano are anatomically sim ple and easy to treat, a significant number are high or anatomically c omplex and have the potential to become a major management problem. Me thods: One hundred anti seven consecutive patients undergoing surgery for fistula-in-ano were studied prospectively with standardized anatom ic diagrams. Results: Fistulas were classified as superficial (15%). i ntersphincteric (43%), trans-sphincteric (35%) or 'high' (7%). Within each group fistulas were considered either simple or complex (high tra cks, extra tracks or other complications), Trans-sphincteric fistulas were more often complex than intersphincteric Fistulas (32 vs 6%). A p rior history of perianal sepsis and surgery: was more frequent among t he trans-sphincteric and 'high' groups. An external fistula opening wi thin a narrow are 30 degrees either side or the posterior midline was almost always associated with a simple superficial ol intersphincteric fistula (97%). Anterior and especially posterolaterally located exter nal openings were frequently associated with complex fistulas (16 and 47%, respectively) and often had trans-sphincteric or 'high' tracks (5 8 and 56%). Goodsall's Law was more accurate for posterior (91%) and i ntersphincteric (93%) fistulas than for anterior (69%) and transsphinc teric (68%) fistulas. Histopathology of fistula material showed unrema rkable fistula-in-ano in 87% of requests. Six patients hall unexpected abnormal results, including three new diagnoses of Crohn's disease. C onclusions: The presence of additional anatomic complexity should alwa ys bz anticipated in trans-sphincteric fistulas. Transsphincteric and 'high' fistulas are more likely to occur in females, and in patients w ith previous perianal sepsis or surgery for fistula. External openings close to the posterior midline almost always underlie simple fistulas , whereas posterolateral external openings are predictive of complex f istulas.