Sphincterotomy 

Sphincterotomy is a surgical procedure that involves the removal of fissures from the sphincter.

The word is formed from sphincter + otomy (to cut, to separate).

A sphincter is a structure, usually a circular muscle, that normally maintains constriction of a natural body passage or orifice and which relaxes as required by normal physiological functioning. There are over 40 different sphincters in the human body; some of these sphincters are microscopic in size.

A sphincterotomy is a procedure performed to treat anal fissures. An anal fissure is a small tear or cut in the skin that lines the anus.

An anal fissure is a split in the lining of the rectum, possibly resulting from a hard bowel movement.

Muscle spasms and subsequent bowel movements prevent healing. Fissures can be encouraged to heal using topical medications and stool softeners, but severe or recurring fissures may require a sphincterectomy.

During a sphincterotomy, the outermost part of the anal sphincter is cut. This weakens the muscle and relieves the muscle spasms which prevents healing.