(See also Evaluation of Anorectal Disorders Evaluation of Anorectal Disorders The anal canal begins at the anal verge and ends at the anorectal junction (pectinate line, mucocutaneous junction, dentate line), where there are 8 to 12 anal crypts and 5 to 8 papillae. The... read more .)
Anal fissures are believed to result from laceration by a hard or large stool or from frequent loose bowel movements. Trauma (eg, anal intercourse) is a rare cause. The fissure may cause internal sphincter spasm, decreasing blood supply and perpetuating the fissure.
Anal fissures usually lie in the posterior midline but may occur in the anterior midline. Those off the midline may have specific etiologies, particularly Crohn disease Crohn Disease Crohn disease is a chronic transmural inflammatory bowel disease that usually affects the distal ileum and colon but may occur in any part of the gastrointestinal tract. Symptoms include diarrhea... read more . An external skin tag (the sentinel pile) may be present at the lower end of the fissure, and an enlarged (hypertrophic) papilla may be present at the upper end.
Fissures cause pain and bleeding. The pain typically occurs with or shortly after defecation, lasts for several hours, and subsides until the next bowel movement. Examination must be gentle but with adequate spreading of the buttocks to allow visualization.
Chronic fissures must be differentiated from anal cancer Anal Cancer Anal cancer accounts for an estimated 8590 cases and about 1350 deaths in the US annually (1). The main symptom is bleeding with defecation. Diagnosis is by endoscopy. Treatment options include... read more , primary lesions of syphilis Syphilis Syphilis is caused by the spirochete Treponema pallidum and is characterized by 3 sequential clinical, symptomatic stages separated by periods of asymptomatic latent infection. Common manifestations... read more , tuberculosis Tuberculosis (TB) Tuberculosis (TB) is a chronic, progressive mycobacterial infection, often with a period of latency following initial infection. TB most commonly affects the lungs. Symptoms include productive... read more , and ulceration caused by Crohn disease Crohn Disease Crohn disease is a chronic transmural inflammatory bowel disease that usually affects the distal ileum and colon but may occur in any part of the gastrointestinal tract. Symptoms include diarrhea... read more .
Infants may develop acute fissures, but chronic fissures are rare.
(See also the American Society of Colon and Rectal Surgeons’ clinical practice guideline for the management of anal fissures.)
Fissures often respond to conservative measures that minimize trauma during defecation (eg, stool softeners, psyllium, fiber). Healing is aided by use of protective zinc oxide ointments or bland suppositories (eg, glycerin) that lubricate the lower rectum and soften stool. Topical anesthetics (eg, benzocaine, lidocaine) and warm (not hot) sitz baths for 10 or 15 minutes after each bowel movement and as needed give temporary relief.
Topical nitroglycerin 0.2% ointment, nifedipine cream 0.2%, 2% diltiazem gel, and injections of botulinum toxin type A into the internal sphincter relax the anal sphincter and decrease maximum anal resting pressure, allowing healing. When conservative measures fail, surgery (internal anal sphincterotomy) is needed to interfere with the cycle of internal anal sphincter spasm.
The following is an English-language resource that may be useful. Please note that THE MANUAL is not responsible for the content of this resource.
American Society of Colon and Rectal Surgeons: Clinical practice guideline for the management of anal fissures