An anal fissure is the longitudinal erosion and/or ulceration of the epithelium of the lower third of the anal canal. It is usually located on the midline (on the 6th or the 12th hour of the annulus circumference). The presence of multiple fissures may indicate the presence of comorbidities such as Crohn’s or ulcerative colitis.

It is usually caused by a rupture of the rectal mucosa and skin during defecation and is combined to chronic constipation and external sphincter hypertonicity. Causes also include injury during anal sexual intercourse, thrombosed hemorrhoids, etc. Fissures are classified into acute and chronic ones.

Their clinical signs include acute pain following defecation that lasts for a few hours and is repeated after each bowel movement. Occasionally, there may be loss of blood or even pus. Digital examination is very painful and sometimes impossible.

Acute fissures treatment is mainly conservative and involves the administration of topical analgesics and anti-inflammatory ointments and laxatives to restrain constipation. Cleaning with warm (not hot) water helps relieve the symptoms. Other treating options are the use of ointments causing relaxation of the inner sphincter (glycerol trinitrate, diltiazem, nifedipine) as well as botulinum toxin injections.

If conservative treatment fails, it is recommended to dilate the annulus under general anesthesia to cause relaxation and temporary paralysis of the rectal sphincter as well as symptom relief with gradual remission of the inflammation.

Chronic fissures are surgically treated. In case of annulus dilation it is recommended to excise the fissure and the scar tissue, and to partially dissect the inner sphincter (lateral internal sphincterectomy). In preoperative and postoperative assessment of the sphincter functionality, the role of anorectal manometry and interectal endoscopic ultrasound is especially important. This procedure requires experience and special care from the surgeon to avoid postoperative incontinence.