Lateral Internal Sphincterotomy - Surgical Technique

Surgical Technique

Lateral internal sphincterotomy is a minor operation which can be carried out under either local or general anaesthesia; a report in 1981 showed that general anaesthesia is preferable due to high rates of fissure recurrence in patients treated under local anaesthesia. This operation is generally carried out as a day case procedure. It can be performed with either "open" or "closed" techniques:

• the open technique involves making an incision across the intersphincteric groove, separating the internal sphincter from the anal mucosa by blunt dissection, and dividing the internal sphincter using scissors.
• the closed technique or subcutaneous technique involves making a small incision at the intersphincteric groove, inserting a scalpel with the blade parallel to the internal sphincter and advancing it along the intersphincteric groove, and then rotating the scalpel towards the internal sphincter and dividing it.

In both techniques the lower one third to one half of the internal sphincter is divided, to lower the resting pressure without destroying the effect of the sphincter. The closed technique results in a smaller wound, but both techniques appear to be similarly effective.