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Fissures are a small split or tear in the skin. Anal fissures are small splits or tears in the mucosal lining of the lower rectum and can range from involving only the epithelium to encompassing the entire thickness of the anal mucosa.1 Anal fissures are common, with a similar incidence in men and women, and they can occur at any age.2 Individuals at risk of developing anal fissures include patients with inflammatory bowel disease (IBD), women who are in the postpartum period, and elderly adults. Anal fissures can be acute or chronic. The goal of treatment is to relieve pain, constipation, and spasms, as well as reduce the resting internal anal sphincter pressure so that the fissure can fully heal. Therapy for anal fissures ranges from conservative measures to pharmacologic treatments to surgical interventions.
Anal fissures result from trauma to the inner lining of the anus. The exact etiology is unknown. Acute anal fissures can be caused by trauma from dry, hard stools that are difficult to pass, childbirth, Crohn’s disease, anal intercourse, or anal instrumentation. Hard stools are more often the cause of anal fissures, but loose stools also cause the tears. Increased tension in the anal sphincter causes a spasm after a bowel movement, which decreases blood flow to the area and impedes healing. During a bowel movement, the fissure is stretched, leading the injured tissue into contact with stool, which can further delay healing.
An acute anal fissure is one that heals in less than four weeks. Risk factors for progression from an acute to a chronic anal fissure, or one that lasts more than four to six weeks without healing, include internal anal sphincter hypertonia, as well as location of the tear. Underlying pathology is the cause of primary but not secondary anal fissures. Pathologies that may lead to fissures include syphilis, chronic IBD, tuberculosis, and HIV/AIDS.3 Posterior fissures are in a poorly perfused area of the anus, the posterior anal canal. Patients with posterior midline anal fissures have increased anal resting pressure, which causes hypertonia and thus delayed healing related to the decrease in blood perfusion pressure to the lining of the anus. The lack of blood flow, in turn, leads to an ischemic ulcer, a chronic anal fissure.
Symptoms of anal fissures can range from minor irritation to severe pain with and after bowel movements. Pain that lasts from minutes to hours after a bowel movement is common, whereas in between bowel movements, patients are asymptomatic. Reports of bright red blood on toilet paper with bowel movements are not unusual, and many patients are afraid to have bowel movements because of the pain and therefore will delay defecation.
No occupations are associated with the development of anal fissures. Anal surgery is a predisposing risk.1 Scar tissue from the surgery may develop and cause stenosis or bonding of the anal canal, which can increase pressure and make the area more susceptible to trauma from a bowel movement. Studies have found an association between anal fissures and the use of nicorandil, a drug that is used to treat angina pectoris but is not currently available in the United States.4
Examination of the anal area in a patient with suspected anal fissures is best done with the patient standing and leaning over the examination table so that the entire anus and rectum can be viewed. The alternative for patients who cannot tolerate that position is lying on the left lateral side with the right knee pulled toward the chest. On examination, a tear or crack in the skin will be visible and painful to palpation. A majority of anal fissures occur at the posterior midline. In males, about 1% of all fissures occur at the anterior midline, whereas in females the incidence is approximately 10%.1 In rare presentations (about 2%), fissures are present at both sites.4 An indicator that a fissure is chronic is an anal skin tag (also called a sentinel pile) present distal to the fissure or hypertrophied anal papilla inside the anal canal. Patients who have anal fissures that present away from the midline should be further assessed for disease processes such as HIV/AIDS, Crohn’s disease, tuberculosis, or a sexually transmitted infection.