Lateral anal sphincterotomy

Lateral anal sphincterotomy

In this operation, the internal sphincter is divided away from - the fissure itself – usually either in the right or the left lateral positions. The procedure can be carried out using an open or a closed method, under local, regional or general anaesthesia, and with the patient in the lithotomy or prone jack-knife position. The distal internal sphincter is palpated with a bivalved speculum at the intersphincteric groove. In the closed method, a small longitudinal incision is made over this, and the submucosal and intersphincteric planes are carefully developed to allow precise division of the internal sphincter with a knife or scissors to the level of the apex of the fissure ( Figure 80.18 ); the wound is then closed with absorbable sutures. Alternatively , either plane can be entered using a scalpel (no. 11 blade), with the blade advanced parallel to the sphincter and then rotated such that the sharp edge faces the internal sphincter, which can then be divided along its distal third. Pressure should be applied to the wound for a few minutes to prevent haematoma formation. In the open technique, the anoderm overlying the distal internal sphincter is divided longitudinally to expose the sphincter, which is divided, and the wound is closed with absorbable sutures. Although the fissure needs no specific attention, problematic papillae and external tags can be excised. The optimal amount of sphincter to be divided is a matter of debate, and additional factors have to be considered such as patient age, sex, previous vaginal delivery and operations on the anal canal. Early complications of sphincterotomy include haemorrhage, haematoma, bruising, perianal abscess and fistula. Healing rates are in the range of 85%, but there is also a significant risk of altered continence (9% flatus incontinence, 6% soiling, <1% solid stool incontinence).

Figure 80.18 Lateral internal sphincterotomy. A dissecting scissors is used to open the intersphincteric space and divide the internal anal sphincter. (Reproduced with permission from O’Connell PR, Madoff RD, Solomon MJ (eds). Operative surgery of the colon, rectum and anus , 6th edn. Boca Raton, FL: CRC Press, 2015.)