Colorectal

Lateral Internal Sphincterotomy

LATERAL INTERNAL SPHINCTEROTOMY

Indication: Chronic anal fissure (typically posterior midline) failing conservative and topical medical therapy. Elevated internal sphincter tone contributes to ischaemia and failure to heal.

Patient Position: Lithotomy or left lateral.

Anaesthesia: General, spinal, or local with sedation.

Procedure:
1. Examination under anaesthesia. Fissure confirmed (typically posterior midline — chronic changes: deep fissure, exposed internal sphincter fibres, sentinel pile, hypertrophied anal papilla).
2. Lateral position chosen (left lateral at 3 o'clock or right lateral at 9 o'clock).