An anal fissure is an acute longitudinal tear or a chronic ovoid ulcer in the squamous epithelium of the anal canal. It causes severe pain, sometimes with bleeding, particularly with defecation. Diagnosis is by inspection. Treatment is local hygiene, stool softeners, topical measures, and sometimes botulinum toxin injection and/or a surgical procedure.
(See also Evaluation of Anorectal Disorders.)
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.
Symptoms and Signs of Anal 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. 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, primary lesions of syphilis, tuberculosis, and ulceration caused by Crohn disease.
Infants may develop acute fissures, but chronic fissures are rare.
Diagnosis of Anal Fissure
Clinical evaluation
Diagnosis of anal fissure is made by inspection. Unless findings suggest a specific cause or the appearance and/or location is unusual, further studies are not required.
Treatment of Anal Fissure
Stool softeners, fiber supplements
Protective ointments, sitz baths
Nitroglycerin ointment, topical calcium channel blocker, or botulinum toxin type A injection
(See also the American Society of Colon and Rectal Surgeons’ 2016 clinical practice guideline for the management of anal fissures.)
When conservative measures fail, surgery (internal anal sphincterotomy) is needed to interfere with the cycle of internal anal sphincter spasm.
More Information
The following English-language resource 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 (2016)
