Information about Anal Fissures

An anal fissure is a tear in the skin that lines the anal canal, the part of the rectum closest to the anus. Most experts believe that anal fissures are caused by passing hard stool, which can tear the skin of the anal canal and cause pain and bleeding.

Anal fissures are a common problem that affects most people at some point in their life. Many anal fissures heal on their own, but medication or surgery is needed if they become a chronic problem.

Causes of Anal Fissure

Although constipation is a common cause of anal fissures, other causes include diarrhea, childbirth, colonoscopy or sigmoidoscopy, and surgery. A high resting anal pressure (tight anus) also appears to be a factor. Tightness, or spasm, within the anus also interferes with blood supply to the anal canal, which may prevent healing of a tear.

Furthermore, an anal fissure may be a sign of a more serious condition, such as:

  • syphilis
  • herpes
  • gonorrhea
  • chlamydia
  • HIV infection
  • AIDS
  • Crohn's disease
  • ulcerative colitis
  • tuberculosis
  • tumor

Symptoms of Anal Fissure

The hallmark of anal fissures is pain, sometimes severe, during or after a bowel movement. The pain may be brief or continue for hours afterwards. Bleeding frequently accompanies the bowel movement, and the blood appears on the outside of the stool. About half of individuals with anal fissures also experience anal itching.

Anal fissures are frequently confused with hemorrhoids, but hemorrhoids usually do not cause pain while passing stool. Nonetheless, you can have both hemorrhoids and an anal fissure.

Diagnosis of Anal Fissure

To diagnose anal fissures, the doctor spreads apart your buttocks to view the anus. The fissure appears as a tear, most often in the middle of the anus toward the back of the body. While an anal fissure is usually easy to see, your doctor may use an instrument called an anoscope to view the inside of the anal canal.

Treatment of Anal Fissure

Between 50 and 90 percent of anal fissures heal on their own or with simple treatments such as:

  • eating a high-fiber diet
  • increasing your intake of water and other fluids
  • using stool-softening laxatives
  • taking warm sitz baths for 10 to 15 minutes after each bowel movement

Topical corticosteroids and anesthetics are not effective.

If an anal fissure does not heal after six weeks of the simple treatments described above, you have a chronic anal fissure. This usually requires additional treatment, the most common of which is nitroglycerin ointment. A pea-sized amount of the ointment is placed on the fissure two to three times a day for up to eight weeks.

This treatment heals between 70 and 80 percent of chronic anal fissures. The most common side effect of the ointment is headaches, which can be severe, although pain relievers such as acetaminophen (Tylenol) and aspirin may relieve the pain.

Other medications used for anal fissures are calcium channel blockers—medications commonly used to treat high blood pressure and chest pain. The oral calcium channel blocker nifedipine (Procardia and other brands) heals 60% of chronic anal fissures when used for eight weeks. Nifedipine may work by decreasing anal pressure.

Another calcium channel blocker, diltiazem (Cardizem), which is available in oral and cream forms, also appears to be beneficial for the treatment of chronic anal fissures. Common side effects include headache and swelling of the feet and ankles.

Low doses of botulinum toxin A (Botox), a paralyzing agent, also can be used to treat anal fissures. Studies show that a single injection can heal up to 80 percent of chronic anal fissures, possibly by lowering anal pressure. Although it has a high success rate, some people find the injections painful. Rare complications include bleeding, blood clots under the skin around the anus, loss of bowel control, and sepsis (a bacterial infection of the blood).

If a chronic anal fissure does not heal with medications, surgery may be necessary. Sphincterotomy, which involves cutting part of the muscle in the anal canal, is the surgery of choice. It helps heal about 98 percent of anal fissures. Sphincterotomy decreases the spasms and pressure in the anal canal and is a good option for people with chronic anal fissures and a high resting anal pressure.

Another surgical treatment, anal dilation or a four-fingered anal stretch, heals 40 to 90 percent of chronic anal fissures. In this procedure, the physician uses four fingers to hold the anus open for four minutes to reduce spasms and pressure in the anal canal. However, almost 40 percent of people who undergo anal dilation have difficulty controlling flatulence or soil themselves occasionally; some 16 percent experience loss of bowel control.

Publication Review By: H. Franklin Herlong, M.D.

Published: 28 Mar 2011

Last Modified: 02 Oct 2014