Several muscles encircle the anal canal and work together to control bowel movements. The inner muscle, just beneath the lining of the anal canal, is called the internal (involuntary) anal sphincter. This muscle is usually covered by skin. When a bowel movement occurs, the muscle relaxes to allow the stool to pass.
Tears that occur along the anal canal are called anal fissures. When a tear occurs, pain makes the muscle fibers contract, stopping the stool from passing. The fissure pulls apart when the muscle contracts (anal spasm). In turn, this affects the small blood vessels that carry nutrients and oxygen to the torn tissues. As a result, healing is slowed.
The pain and discomfort of an anal fissure usually gets worse when a person has a bowel movement. The pain tends to linger a long time afterward. There may be bleeding from the tear as well. Constipation may also occur as the condition gets worse.
Causes and Risk Factors
A fissure can occur from:
- Passing a hard stool or prolonged episode of diarrhea
- Lack of fiber in the diet and/or water with that fiber
- Food that creates a rough passage through the digestive system, such as popcorn, nuts or tortilla chips
Diagnosis of this condition is usually done on the basis of the symptoms and a physical examination.
Most fissures can heal by following good elimination habits.
- Take plenty of water and fiber
- Avoid foods such as popcorn, nuts or tortilla chips
- Avoid constipating foods
Additionally, the following measures can help:
- Warm baths (sitz baths)
- Use a topical anesthetic cream
- Avoid using hemorrhoid suppositories. These hard, bullet-like medications are painful to insert and sometimes tear the fissure even more.
If pain persists, consult a colorectal surgeon. In addition, the surgeon may prescribe medications (such as topical nitroglycerin ointment or diltiazem) that relax the anal spasm, improve blood supply to the anus and promote healing.
If medical treatments fail, an outpatient surgical procedure can relax the internal sphincter muscle to allow the fissure to heal.