A 40-year-old man presents with a fistula-in-ano. The external opening is located 4 cm anterior to the anal verge. According to Goodsall's rule, which describes the most likely course and internal opening?
- A Straight radial tract to the anterior crypt of the same quadrant
- B Curved tract leading to an internal opening at the posterior midline ✓
- C Straight tract to the contralateral posterior crypt
- D Multiple intercommunicating tracts to the lateral walls
Correct answer: B. Curved tract leading to an internal opening at the posterior midline
Explanation
Goodsall's rule states that an external opening anterior to the transverse anal line and more than 3 cm from the verge follows a curved course to a posterior midline internal opening. Anterior openings within 3 cm have a radial straight tract. This pattern helps the surgeon locate the internal opening and avoid missing secondary tracts.
Reference: Bailey & Love's Short Practice of Surgery, 27th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.