Description

Anal fissure is a benign anorectal disease characterized by a knifelike tearing sensation on defecation. An anal fissure is a tear in the lining of the anal canal distal to the dentate line, most commonly in the posterior midline.

Epidemiology

Very common anorectal condition often confused with hemorrhoids

• Common in infants age 6–24 months; not common in older children; suspect abuse or trauma. Elderly are spared due to lower resting pressure in the anal canal.
• Predominant sex: Male = Female, but women are more likely to get anterior midline tears (25% vs. 8%).

• 80% of infants, usually self-limited
• 20% of adults, most of whom do not seek medical advice, have symptoms referable to the anorectum.

Risk Factors

• Constipation
• Passage of hard or large-caliber stool
• High resting tone of internal anal sphincter (prolonged sitting)
• Trauma (anal sex)
• Inflammatory bowel disease (Crohn disease)
• Syphilis
• Tuberculosis

Genetics
None known

General Prevention

Avoid constipation and prolonged sitting on toilet.

Pathophysiology

High resting pressure within the anal canal can lead to ischemia of the anodermal tissues, resulting in splitting of the tissues with passage of stool. Exposed internal sphincter muscle spasms cause the knifelike pain.

Etiology

Splitting of susceptible anodermal tissue

Commonly Associated Conditions

Constipation, Crohn disease, tuberculosis, leukemia, and HIV