An anal fissure (fissure-in-ano) is a small, oval shaped tear in skin that lines the opening of the anus. Fissures typically cause severe pain and bleeding with bowel movements. Fissures are quite common in the general population, but are often confused with other causes of pain and bleeding, such as hemorrhoids.
Anal fissures can occur at any age and have equal gender distribution. Most (85-90%) fissures occur in the posterior (back) midline of the anus with about 10-15% occurring in the anterior (front) midline. A small number of patients may actually have fissures in both the front and the back locations. Fissures located elsewhere (off to the side) should raise suspicion for other diseases (see below) and will need to be examined further.
WHAT ARE THE SYMPTOMS OF AN ANAL FISSURE?
The typical symptoms of an anal fissure include pain and bleeding with bowel movements. Patients note severe pain during, and especially after a bowel movement, lasting from several minutes to a few hours. Patients often notice bright red blood from the anus that can be seen on the toilet paper or on the stool. Between bowel movements, patients with anal fissures are often relatively symptom-free. Many patients are fearful of having a bowel movement and may try to avoid defecation secondary to the pain.
WHAT CAUSES AN ANAL FISSURE?
Fissures are usually caused by trauma to the inner lining of the anus. A hard, dry bowel movement is typically responsible, but loose stools and diarrhea can also be the cause. The inciting trauma to the anus produces severe anal pain, resulting in anal sphincter spasm and a subsequent increase in anal sphincter muscle pressure. The increase in anal sphincter muscle pressure results in a decrease in blood flow to the site of the injury, thus impairing healing of the wound. Ensuing bowel movements result in more pain, more anal spasm, diminished blood flow to the area, and the cycle is propagated. Treatment strategies are aimed at interrupting this cycle to promote healing of the fissure.
Anal fissures may be acute (recent onset) or chronic (typically lasting more than 8-12 weeks). Acute fissures may have the appearance of a simple tear in the anus, whereas chronic fissures may have swelling and scar tissue present. Chronic fissures may be more difficult to treat and may also have an external lump associated with the tear, called a sentinel pile or skin tag, as well as extra tissue just inside the anal canal, referred to as a hypertrophied papilla.
Quite commonly, anal fissures are misdiagnosed as hemorrhoids by the patient or the primary care physician due to some similar symptoms between the two. This delay in diagnosis may lead to an acute fissure becoming a chronic one and, thus, more difficult to treat. Misdiagnosis of an anal fissure may also allow other conditions to go undetected and untreated, such as serious infections or even cancer. These less common causes of fissures include inflammatory conditions and certain anal infections or tumors, such as Crohn’s disease, ulcerative colitis, syphilis, tuberculosis, leukemia, HIV/AIDS, or anal cancer. These diseases cause atypical fissures that are located off the midline, are multiple, painless, or non-healing after proper treatment.