Home > Patients & Visitors > Health Library > Anal Fissures: Internal Anal Sphincterotomy
Surgery may be needed if medicine fails to heal a tear
(fissure) in the
anus. The preferred procedure is an internal anal
sphincterotomy. A doctor makes a small incision in the internal anal sphincter,
one of two muscles that control the anus. This can be done as outpatient
local anesthesia or
The internal anal
sphincter is always under tension, also known as resting pressure. If that
pressure becomes too high, a fissure may form or an existing one may not heal.
The incision reduces the resting pressure, allowing the fissure to heal.
It's important to understand that, even with surgery, an anal fissure
must heal on its own. A sphincterotomy involves operating on the sphincter
muscles, not closing the actual fissure.
Internal anal sphincterotomy has a better success rate than any
medicine that is used to treat long-term anal fissures. The results last
longer, and fewer people have anal fissures come back after surgery than after
treatment with medicine.footnote 1
In some studies,
a greater number of people who had internal anal sphincterotomy had some
inability to control gas or stool (incontinence)
after surgery compared to people treated with medicine. Despite these results,
satisfaction with this surgery is high. And a review of many studies showed
that the risk of incontinence was 8%. This means that about 8 out of 100 people
who had the surgery had some problem with incontinence. But this rate was not
very different from the rates seen in people who were treated with medicine for
their chronic anal fissures.footnote 2
study showed that internal anal sphincterotomy was better than nitroglycerin
cream at healing chronic anal fissures. And there was no difference in
long-term continence between the people who used nitroglycerin cream and the
people who had surgery.footnote 3
If you are deciding
whether to have this surgery, it is important that you consider the chance of
incontinence. In some cases,
the risk of incontinence is too great to justify doing internal anal
sphincterotomy. This may be true for women who develop a fissure while giving
birth, because they typically don't have a high resting pressure in their
internal sphincter. A procedure called anal advancement flap may be done
instead of sphincterotomy. In this procedure, the
edges of the fissure are removed, and healthy tissue is sewn over the
Nelson RL (2014). Anal fissure (chronic). BMJ Clinical Evidence. http://clinicalevidence.bmj.com/x/systematic-review/0407/overview.html. Accessed January 8, 2015.
Nelson R (2006). Non-surgical therapy for anal fissure. Cochrane Database of Systematic Reviews (4).
Brown CJ, et al. (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. Diseases of the Colon and Rectum, 50(4): 442-448.
ByHealthwise StaffPrimary Medical ReviewerAnne C. Poinier, MD - Internal MedicineE. Gregory Thompson, MD - Internal MedicineSpecialist Medical ReviewerC. Dale Mercer, MD, FRCSC, FACS - General Surgery
Current as ofMay 5, 2017
Current as of:
May 5, 2017
Anne C. Poinier, MD - Internal Medicine & E. Gregory Thompson, MD - Internal Medicine & C. Dale Mercer, MD, FRCSC, FACS - General Surgery
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