Lateral internal sphincterotomy is anoperation performed on theinternal anal sphincter muscle for the treatment of chronicanal fissure. The internal anal sphincter is one of two muscles that comprise the analsphincter which controls the passage offeces. The procedure helps by lowering the resting pressure of the internal anal sphincter, which improves blood supply to the fissure and allows faster healing.[1] The procedure has been shown to be very effective, with 96% of fissures healing at a median of 3 weeks in one trial.[2]
Lateral internal sphincterotomy is the preferred method of surgery for persons with chronic anal fissures, and is generally used when medical therapy has failed.[1] It is associated with a lower rate of side effects than older techniques such as posterior internal sphincterotomy and anoplasty,[3] and has also been shown to be superior to topicalglyceryl trinitrate (GTN 0.2% ointment) in long term healing of fissures, with no difference in fecal continence.[4]
Lateral internal sphincterotomy is a minor operation which can be carried out under eitherlocal orgeneral anaesthesia; a report in 1981 showed that general anaesthesia is preferable due to high rates of fissure recurrence in patients treated under local anaesthesia.[5] This operation is generally carried out as a day case procedure. It can be performed with either "open" or "closed" techniques:[6]
theopen 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.
theclosed technique orsubcutaneous technique involves making a small incision at the intersphincteric groove, inserting ascalpel 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.[7]
Minorfecal incontinence and difficulty controlling flatulence are common side effects following surgery.[8] Persistent minor fecal incontinence has been reported in 1.2% to 35% of patients; however, this does not appear to be significantly different to the rate of minor fecal incontinence experienced by patients treated with topical GTN.[1]
Hemorrhage can occur, more often with the open technique, and may requiresuture ligation.
^Brown CJ, Dubreuil D, Santoro L, Liu M, O'Connor BI, McLeod RS (April 2007). "Lateral internal sphincterotomy is superior to topical nitroglycerin for healing chronic anal fissure and does not compromise long-term fecal continence: six-year follow-up of a multicenter, randomized, controlled trial".Dis. Colon Rectum.50 (4):442–8.doi:10.1007/s10350-006-0844-3.PMID17297553.S2CID24579316.
^Keighley MR, Greca F, Nevah E, Hares M, Alexander-Williams J (June 1981). "Treatment of anal fissure by lateral subcutaneous sphincterotomy should be under general anaesthesia".Br J Surg.68 (6):400–1.doi:10.1002/bjs.1800680611.PMID7016242.S2CID40048690.
^abCorman, Marvin L (2005).Colon and rectal surgery (5 ed.). Lippincott Williams & Wilkins. p. 264.ISBN978-0-7817-4043-2.
