An anal fissure is a tear or ulcer in the lining of the anal canal. It is most commonly caused by damage from passing hard, dry feces due to constipation. It is also common during pregnancy and after delivery.
Less common causes include an inflammatory bowel disease, such as Crohn’s disease or ulcerative colitis , or having unusually tight anal sphincter muscles.
The main symptoms are severe pain when defecating and bleeding when defecating (often visible as bright red blood on the feces, toilet paper, or in the toilet bowl).
Most fissures heal by themselves within a few weeks. Measures such as a high-fiber diet to prevent constipation and pain relievers can relieve symptoms and help the healing process. If such treatments are ineffective, surgery may be recommended.