Colorectal

Lateral Internal Anal Sphincterotomy

OPERATION: Lateral Internal Anal Sphincterotomy
ANAESTHETIC: General / spinal / local anaesthesia with sedation
POSITION: Lithotomy

INDICATION:
Chronic anal fissure refractory to conservative measures and topical pharmacological therapy (glyceryl trinitrate / diltiazem / botulinum toxin). [Position: posterior midline]. Anal manometry [if performed] confirming hypertonia. [Sentinel pile and hypertrophied anal papilla present].

PROCEDURE:
WHO Checklist performed. Perineum prepared and draped. Examination under anaesthesia confirmed chronic posterior midline fissure with [sentinel skin tag / hypertrophied anal papilla]. Fissure base curetted. [Sentinel skin tag and hypertrophied anal papilla excised].

Left lateral position chosen. Intersphincteric groove identified at the left lateral position by bidigital palpation. Radial incision made at the left lateral intersphincteric groove. Intersphincteric plane dissected with fine scissors to define the lower border of the internal anal sphincter. Internal anal sphincter visualised under direct vision.

Open lateral internal anal sphincterotomy performed using diathermy — internal sphincter divided from its lower border to the level of the dentate line [/ to the apex of the fissure]. Division confirmed to be confined to the internal sphincter with the external sphincter preserved. Haemostasis achieved. Wound left open to drain.

FINAL EXAMINATION: Anal canal calibre improved. Sphincter tone reassessed — adequate reduction confirmed. No inadvertent injury to external sphincter.

CLOSURE:
Perianal wound left open. Dressing applied.

FINDINGS:
Chronic posterior midline fissure [with / without sentinel pile]. Anal hypertonia confirmed on examination. Internal sphincter divided under direct vision — extent: lower border to dentate line.

EBL: Minimal. COMPLICATIONS: None.

POST-OPERATIVE INSTRUCTIONS:
Regular analgesia. High fibre diet and adequate fluid intake. Stool softener. Sitz baths. Warn patient of small risk of minor incontinence (liquid stool / flatus). Outpatient review at 4–6 weeks to confirm fissure healing.