Fistula-in-ano: a prospective study of 107 patients

Area of Science:

• Colorectal Surgery
• Surgical Anatomy
• Gastroenterology

Background:

• Anal fistulas vary in complexity, with some posing significant management challenges.
• Understanding fistula anatomy is crucial for effective treatment planning.

Purpose of the Study:

• To prospectively analyze the anatomy of anal fistulas in patients undergoing surgery.
• To correlate external opening location and patient history with fistula complexity and track type.

Main Methods:

• Prospective study of 107 consecutive patients undergoing fistula-in-ano surgery.
• Standardized anatomic diagrams used for classification.
• Analysis of fistula type, complexity, external opening location, and patient history.

Main Results:

• Fistulas classified as superficial (15%), intersphincteric (43%), trans-sphincteric (35%), or high (7%).
• Trans-sphincteric fistulas were more frequently complex (32%) than intersphincteric (6%).
• Posterolateral external openings were predictive of complex fistulas (47%) and trans-sphincteric or high tracks (56-58%).
• Goodsall's Law accuracy varied by fistula location.
• Unexpected findings included three new Crohn's disease diagnoses.

Conclusions:

• Trans-sphincteric and high anal fistulas often exhibit complexity and are more common in females or those with prior perianal sepsis/surgery.
• Posterior midline external openings typically indicate simple fistulas.
• Posterolateral external openings are strong predictors of complex anal fistulas, necessitating careful surgical consideration.