Anal fissures occur when tears form in the lining of the anus, the opening of the rectum to the outside of the body. Constipation--straining during bowel movements or passing hard stools--can cause the anus to tear, and fear of the pain of a bowel movement can inhibit people with anal tears from having normal bowel movements, leading to a cycle of constipation and anal fissures.
Cause
The Merck Manual states that anal fissures "result from laceration by a hard or large stool" such as those passed during constipation. People prone to constipation, such as infants, older people and pregnant women, also have the highest risk for anal fissures. When stools pass through the large intestine (colon) too slowly, or when the colon absorbs too much water, the stools harden.
Effect: Pain
Anal fissures can cause excruciating pain during and after a bowel movement. The American Gastroenterological Association says that some patients compare the sensation to passing razor blades or shards of glass. The pain associated with defecation often causes people with an anal fissure to dread defecation to the point where they will resist the need, a situation that can cause constipation, worsening the anal fissure and preventing its healing.
Effect: Spasm
The anal sphincter is a ring of muscle that controls the opening and closing of the anus to regulate defecation. According to the Mayo Clinic, constipation can also result when anal fissures cause the sphincter to contract spastically, disrupting the normal pattern of defecation.
Treatment
Conservative treatment of anal sphincters necessarily involves therapies to prevent constipation. This increases the likelihood of healing and decreases the risk of recurrence. For acute treatment, doctors often recommend stool softeners and fiber laxatives. In the long term, lifestyle changes like increasing exercise, adding fiber to the diet and staying well-hydrated can help prevent constipation and recurrence of an anal fissure.
Clinical Trials
The American Gastroenterological Association reports on the outcomes of clinical trials to assess the role of constipation treatment and prevention in the healing and prevention of recurrence of anal fissures. In two separate trials, about 44 percent of patients with anal fissures healed with a regimen of sitz baths and stool bulking agents to prevent constipation. In another trial comparing a regimen of sitz baths and bran supplementation to add fiber to the diet and prevent constipation versus medicated creams for the anus, bran supplementation outperformed both medications in terms of percent of patients healed and the speed of healing. Anal fissures healed in approximately 87 percent of the patients who ate 10 g of unprocessed bran twice per day.
