A 45-year-old woman presents with chronic proctalgia and painful defecation. Examination reveals an anal fissure in the posterior midline with a sentinel skin tag. First-line medical therapy (topical GTN) has failed for 8 weeks. The most appropriate next intervention is:

• A Lateral internal sphincterotomy (LIS)
• B Posterior internal sphincterotomy
• C Fissurectomy with advancement flap
• D Botulinum toxin injection into the internal sphincter ✓

Explanation

When first-line topical agents (GTN, diltiazem) fail for chronic anal fissure, botulinum toxin injection into the internal sphincter is the preferred second-line intervention due to its reversibility and avoidance of permanent incontinence risk. Lateral internal sphincterotomy (LIS) is the gold standard for definitive treatment and has the highest healing rates (~95%), but carries a 1-5% risk of permanent fecal incontinence. In women, especially those with obstetric sphincter injuries, this risk is higher, making botulinum toxin a safer intermediate step.

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.