Anal Fissure

What is an Anal Fissure and What Should I Know?

Illustration of an anal fissure.
Illustration of an anal fissure.

An anal fissure is a small tear in the skin overlying the anus that may occur when a hard stool is passed. Constipation is the most common cause of anal fissures.

What Are the Symptoms and Signs of an Anal Fissure?

  • Pain during a hard bowel movement, and sharp pain that continues afterward are the most common symptoms of an anal fissure.
  • Sitting can be quite painful with an anal fissure.
  • You may see a few drops of blood in the toilet bowel or when wiping. In an infant, there may be blood in the diaper.

What Causes Anal Fissures?

The sphincter muscles that surround the anus and help prevent stool leakage may go into spasm and cause longer-lasting pain with an anal fissure.

How Are Anal Fissures Diagnosed and Treated?

  • Anal fissures are diagnosed by taking your medical history and an inspection of the anus. No other tests are usually needed.
  • Treatment basics include drinking more fluid and eating a high fiber diet. Stool softeners, fiber supplements, and laxatives may be prescribed. Surgery is considered only after diet and medications have failed.

How Long Does It Take for an Anal Fissure to Heal?

  • Usually, it takes about four to six weeks for an anal fissure to heal.

What Are the Symptoms and Signs of Anal Fissures?

  • Severe pain during a bowel movement followed by continuing pain is the classic symptom of an anal fissure.
  • There is a vicious cycle of constipation causing pain, which makes the anal sphincter muscles go into spasm.
  • This causes more pain and spasms, which makes having a bowel movement more difficult and worsens the constipation.
  • The pain is significant enough to make sitting down even more painful.
  • There also may be a few drops of bright red blood in the toilet bowel or when wiping, but significant bleeding usually doesn't occur.

What Causes Anal Fissures?

The anal canal is the last part of the colon or large intestine as it exits the body. It is very short, approximately 1-2 inches long and has two circular muscles that help control the passage of bowel movements. The internal anal sphincter is not a voluntary muscle, and it is always contracted to help prevent stool from leaking out. The external anal sphincter is a voluntary muscle.

  • An anal fissure describes a tear in the skin lining of the anal canal, or trauma to the anus and anal canal. The trauma usually occurs individual strains during a bowel movement or with constipation. Often, the individual may remember the exact bowel movement during which their pain began.
  • An acute anal fissure describes a tear in the superficial layer of skin.
  • A chronic anal fissure develops over time if the superficial tear does not heal. The tear extends deeper into the mucosa or tissue that lines the muscle of the internal anal sphincter.

What If My Baby Has An Anal Fissure?

  • Anal fissures routinely occur in infants, and are the most common reason for the presence of blood in the diaper. The most frequent cause is the passage of a hard bowel movement. The infant may grunt or cry when trying to pass the hard stool and drops of blood may be seen on the diaper. Blood is not mixed in with the stool.
  • It is important not to ignore blood in an infant's bowel movement or diaper because an anal fissure may not be the cause. It is reasonable and appropriate to contact a health care practitioner to arrange a visit.
  • If constipation is the cause of the anal fissure, adding corn syrup to the formula may be helpful. If the infant is older than 3-4 months, some fruit juice may also help with the bowel movement. The health care practitioner is a good resource for information.

When Should You Call a Doctor for an Anal Fissure?

  • Blood in the stool is never normal and any bleeding should prompt a call to a health care practitioner.
  • Bleeding from an anal fissure is minimal, and usually only a few drops of blood are seen in the toilet bowel or when wiping.
  • The blood is not mixed in with the stool.
  • If there is significant amount of bleeding or if the patient complains of lightheadedness, shortness of breath, or abdominal pain, emergency medical services should be activated (call 911).
  • The pain of an anal fissure can be quite severe and it is reasonable to contact a care practitioner for advice about the diagnosis and options for pain relief.

How Are Anal Fissures Diagnosed?

  • The diagnosis of anal fissure is most commonly made after the health care practitioner takes a history of the patient's complaint and performs a physical examination.
  • The history of constipation followed by a painful bowel movement and rectal that continues afterwards is often enough to make the preliminary diagnosis.
  • Physical examination is usually limited to inspection of the anus, looking for the crack or tear in the skin surrounding the anus.
  • Because of the amount of pain and discomfort, the rectal examination, where a finger is inserted into the rectum to feel for abnormalities and to check for blood in the stool, is usually deferred.
  • If the fissure is not seen and there is doubt about the diagnosis, a flexible sigmoidoscopy may be considered, where the health care practitioner inserts a short lighted tube into the anus to inspect the area.
  • Usually, lidocaine ointment is used as an anesthetic to make the procedure less uncomfortable.
  • No other blood tests or X-rays are needed.
  • Anal fissures that are due to constipation usually are found in the midline. If the fissure is located off to the side, other underlying medical conditions may be the cause, including Crohn's disease (a type of inflammatory bowel disease), HIV infection, and cancer.

Home Remedies for Anal Fissures

  • Initial treatments for anal fissures that are often very successful are designed to make the stool softer, easier to pass, and prevent constipation.
  • Drinking more fluids and eating a high fiber diet may be supplemented by stool softeners and bulking agents.
  • Occasionally laxatives may be used to help promote a bowel movement but their long-term use is not always appropriate. 
  • The second approach to treatment involves decreasing the anal sphincter spasm. Often all that is needed are regular Sitz baths, sitting in a warm tub of water that allows the muscle to relax.
  • Ointments are available and may be prescribed to help decrease sphincter spasm if basic treatments fail.

How to Treat Anal Fissure with Medications

Medications for the treatment of anal fissures fall into two groups:

Constipation control

Anal sphincter muscle spasm control

  • Nitroglycerin rectal ointment
  • Botox injections into the internal anal sphincter paralyzes the muscle for up to three months and may be considered if routine treatments don't succeed or if there is intractable pain.

What is Anal Fissure Surgery?

  • Surgery is another alternative for anal fissures. It is indicated for chronic anal fissures and potentially for acute fissures that don't resolve after a month of aggressive treatment.
  • Lateral internal sphincterectomy describes the procedure where the thickened internal sphincter muscle is incised to allow it to relax by releasing the tension within the circular muscle, and allowing the fissure to heal. The operation is usually performed under general or spinal anesthesia. Sometimes, when a chronic fissure is present, the surgeon may elect to excise or cut out the fissure at the same time.
  • The pain of the anal fissure resolves almost immediately postoperatively. Laxatives and stool softeners may be recommended for a few days after surgery. A high fiber diet is a lifelong recommendation to prevent recurrence.

Will Treatment or Surgery Cure Anal Fissures?

Medical therapy works more than 80% of the time in treating and preventing future anal fissures. If surgery is required, the success rate is often greater than 95% in preventing recurrences.

How Can You Prevent Anal Fissures?

Preventing constipation and the passage of hard bowel movements prevents anal fissures. Maintaining a high fiber diet and drinking plenty of fluid will promote soft bowel movements, and not only prevents anal fissures but also decreases the risk of developing rectal pain.

Rectal Pain Relief

There are four common causes of rectal pain. Anal fissures, hemorrhoids, anal spasms, and Levator ani syndrome. Pain from conditions that cause rectal pain can be treated by condition. For example, pain from anal fissures can be treated at home by sitting in a tub of very warm water for 20 minutes twice a day, applying hydrocortisone cream to the anus, eating a high fiber diet, and taking stool softeners to make bowel movements less painful.

Jameson, J. Larry, et al. Harrison's Principles of Internal Medicine, 20th Ed. New York: McGraw-Hill Education, 2018.