Local perianal block for anal surgery.

BACKGROUND: We refined a technique for local block of all terminal nerve branches to the anus.

METHODS: A total of 30 consecutive patients with proctological disorders consented to ambulatory (n=29) or hospitalised (n=1) operation with local perianal block for skin tags, Milligan- Morgan haemorrhoidectomy, stapled haemorrhoidopexy or anocutaneous fistulae. Patients were operated prone. A total of 40 ml of a 4.75 mg/ml solution of ropivacaine (Narop; Astra, Sweden) was injected in 8 directions (5 ml each) into the ischiorectal fat immediately peripheral to the external sphincter as anaesthetic columns reaching from the skin to the levator. This injection scheme targets the terminal nerve branches of the anus rather than blocking the trunk of major nerves. The relaxation of a pain-free anus was obtained in 2-3 minutes with exposure similar to a general anaesthetic. Postoperative pain was evaluated on a 0 to 10 visual analogue scale (VAS).

RESULTS: Patients were pain-free at discharge. However, mean postoperative VAS score at 24 hours was 3.2 following Milligan-Morgan haemorrhoidectomy, 4.8 following stapled haemorrhoidopexy and skin tags or polyps excision, and 2.7 after fistula lay-open. At telephone follow-up 1-2 weeks later, the patients were satisfied with the method of anaesthesia and would willingly accept it for any further anal surgery.

CONCLUSIONS: The perianal block is easy to apply and effective as sole method of anaesthesia for proctological operations.