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An anal fissure is a tear or crack in the anal canal. When the fissure first develops, it usually only involves the mucosa, the outermost lining of the canal. If an anal fissure is left unattended, however, it can erode through the entire anal and even create a fistula, a second "anus" opening through the skin.
How Common Are Anal Fissures?
Epidemiologists estimate that 8% of men and 25% of women have anal fissures. This problem is more common among younger people than it is among the elderly. Many women develop anal fissures during pregnancy or labor.
What Causes Anal Fissures?
Doctors don't fully understand why some people develop anal fissures and some do not, but the triggering event seems to be the passage of an especially hard stool through the anal canal. There are no activities or occupations that are especially prone to the development of anal fissures, but prior anal surgery is a risk factor, because it creates adhesions ("tethers," in the medical literature) and scar tissue that can make bowel movement difficult.
Tiny tears in the lining of the anus heal quickly. But when the anus is subjected to repeated passage of hard stool, the tears can deepen and spread through surrounding tissues. When a fissure is advanced enough that it causes bowel spasms, blood flow, which is already low on the posterior side of the anus, is compromised even further, making it difficult for the fissure to heal.
Any trauma to the anal canal can cause a fissure. Receiving anal intercourse, constipation, diarrhea, rectal exams at the doctor's office, colonoscopy, or the insertion of any foreign object into the anus can result in a traumatic wound. Some people don't seek help for anal fissures because they are afraid that their doctors will assume some activity with which they do not wish to be associated is the cause of the problem.
How Can I Tell Whether I Have Anal Fissures?
The most common symptom of anal fissures is bright, red blood on toilet tissue after defecation. Brightly colored blood has been recently shed. Darker blood would suggest a problem "further up," not an anal fissure.
Additionally, anal fissures can cause:
- A few drops of blood in the toilet bowl. Large amounts of blood in the toilet indicates a problem other than anal fissures that should be checked out by a doctor right away.
- Painful spasms after bowel movement. This can lead to avoiding bowel movement, harder stooks, and even worse anal fissures when the bowels eventually move.
- An anal skin tag or scar tissue below the fissure.
Your doctor can tell a lot by the location of the fissure. Usually, but not always, an anal fissure occurs at the midline of the anus. When a fissure breaks out to one side or the other, there may be Crohn's disease (which causes inflammation and tissue destruction throughout the bowel), or an infection. Doctors can diagnose anal fissures just by talking with you, but usually they will look inside your rectum with a device called an anoscope.