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Anal Fissure
What is anal fissure?
A fissure is a small tear, cut or crack in the skin lining which can cause pain and/or bleeding and lead to infection. Anal fissure is the most common cause of painful anal bleeding. Fissures begin as acute linear tears in the skin of the anus. They develop after trauma, usually following a hard stool. Acute fissures can progress to become chronic non-healing ulcers.
Fissures are found in the back of the anal canal in approximately 90 percent of cases. The front of the anal canal is the second most common site. Fissures located in unusual positions can be caused by another condition, including Crohn’s disease, carcinoma or syphilis.
What are the risk factors?
Constipation is linked with the development of fissures, as is straining when having a bowel movement, chronic diarrhea and prior anal surgery. All of these risk factors can affect the elasticity of tissue.
What causes it?
Diarrhea, inflammation or a hard bowel movement can all cause tears in the skin, resulting in fissures. Fissures can occur suddenly, be present for long periods of time or recur frequently. Fissures that occur suddenly are usually caused by changing bowel habits. Those that recur or are chronic can be caused by poor bowel habits, tight anal sphincter muscles or another medical condition.
What are the symptoms?
In most cases, individuals experience extreme pain or burning during and after defecating and may have stool streaked with red blood. Often, pain is so extreme that people may try to avoid having a bowel movement.
How are anal fissures diagnosed?
Fissures that last more than one month may be a symptom of another medical condition, such as inflammatory bowel disease. Therefore, it is important to have a complete medical examination. A manometry test may be recommended to determine if anal sphincter pressures are unusually high. Anal manometry is a painless procedure that measures the overall strength of the pelvic floor muscles and rectal reflexes. The test is performed by placing a thin catheter, perfused by water, into the anus. Pressure monitors inside the catheter transmit the muscle impulses to a graph similar to an electrocardiogram.
Since anal fissures can cause severe discomfort, it may be difficult to perform a detailed examination of the anorectum when the patient is evaluated initially. Occasionally it is necessary to perform examination under anesthesia to determine the cause of severe anal pain in a patient who cannot be adequately examined in the office.
What treatments are available?
Most fissures that occur suddenly can be treated without surgery, through a high fiber diet, fiber supplements, stool softeners and plenty of fluids. Taking a warm bath several times a day can also be helpful in the healing process. Sometimes, medicated creams are prescribed, although narcotic analgesics should be avoided because they can worsen constipation. The goal of these therapies is to interrupt the cycle of constipation, hard stool, repetitive traumatic injury, pain, spasm and non-healing.
Over the past several years, alternative antiobiotic treatments have been developed which may benefit patients with acute and chronic anal fissures. Most of these therapies have been directed at relaxation or temporary paralysis of the internal anal sphincter muscle, in an attempt to increase arterial blood flow to the fissure and promote healing. Relaxation of the internal anal sphincter is mediated by release of nitric oxide, and investigators found that topical application of nitrates to the anal canal produced a decrease in anal canal resting pressure by 20 to 25 percent. Topical nitroglycerin ointment (0.2 to 0.4 percent), applied 2 to 4 times daily has been used to treat patients with both acute and chronic fissures. Initial clinical trials of nitroglycerin ointment were encouraging, although more recent studies have reported mixed results. The major side effect of this therapy is headache, which occurs in 10 to 50 percent of patients.
Use of calcium channel blocker ointments appears to have similar benefits, with a reduced incidence of side effects. Most published studies are from Europe, where investigators report healing of anal fissures in 60 to 80 percent of patients. The side effect of temporary incontinence occurs in a small number of patients, and experience with this therapy in the United States is limited.
Patients with symptomatic fissures who fail medical management should be considered for a minimally invasive surgical procedure called lateral internal sphincterotomy, with the expectation of healing in greater than 90 percent. This is a simple procedure that does not interfere with an individual’s ability to control bowel movements in the future and seems to prevent future fissures. During the procedure, the distal portion of the internal sphincter muscle is divided through a small incision. Healing of the fissure usually occurs within 4 weeks. Complications, including hematoma and abscess formation, are rare.
Minor changes in continence are reported in 10-15 percent of patients undergoing lateral internal sphincterotomy. Women with prior obstetrical injury or patients with chronic diarrhea or irritable bowel syndrome should be approached with caution. Every attempt is made to manage patients with anal fissures non-operatively if they have impaired anal continence, and non-healing ulcers should be biopsied to rule out malignancy.
Sphincterotomy should be performed only in carefully selected patients with Crohn’s disease because of the risks of poor healing and impaired continence should the patient develop other anorectal complications of the disease. Although most anal fissures in Crohn’s disease occur in the middle of the anal canal, there is a higher incidence of lateral location and multiplicity than in the general population. They are often less painful than one would guess, based on their appearance. These ulcers typically have a benign course and respond to non-operative measures aimed at reducing symptoms.
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