A 35-year-old man presents with a 2-week history of severe pain during defecation and a tender, fluctuant mass at the 3 o'clock position in the left lateral decubitus examination. The mass is 3 cm and located intersphincteric. What is the diagnosis?
- A Thrombosed external haemorrhoid
- B Anal fissure with sentinel pile
- C Perianal abscess ✓
- D Anal fistula with an external opening
Correct answer: C. Perianal abscess
Explanation
An acute, tender, fluctuant perianal mass is a perianal abscess until proven otherwise. The intersphincteric location at 3 o'clock is the most common site. A thrombosed external haemorrhoid presents as a firm, non-fluctuant lump at the anal verge, not intersphincterically. An anal fissure causes severe pain but presents with a linear tear, not a fluctuant mass. An anal fistula may have an external opening but is typically chronic with intermittent discharge, not an acute fluctuant abscess.
Reference: Bailey and Love's Short Practice of Surgery, 27th ed.
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Written and medically reviewed by the StethoPrep medical team.