This disorder is the result of a linear tear of the anal canal beginning at or just below the dentate line and extending distally along the anal canal. The epithelium in this area consists of anoderm, which has a rich supply of somatic sensory nerve fibers. Consequently, anal fissures are the most common cause of painful rectal bleeding.
Anal fissures are often associated with swelling of the surrounding tissues, producing hypertrophic papillae proximally and the characteristic sentinel pile distally. The latter is frequently misdiagnosed as an external hemorrhoid when in actuality it is the result of edema and fibrosis secondary to the ulcerating fissure. In more than 90 percent of cases, anal fissures occur in the midline posteriorly. In 10 percent of women but in only 1 percent of men, it may be in the midline anteriorly. This almost constant location of anal fissures may be because of the posterior angulation of the rectum on the anus where the posterior midline of the anorectal canal becomes the "lesser curvature" for the passage of stool. A fissure not located in the midline should arouse suspicion that another, potentially life-threatening cause may be involved. Such diagnostic possibilities include Crohn's disease, chronic ulcerative colitis, squamous cell carcinoma of the anus, adenocarcinoma of the rectum invading the anal canal, localized anal cancers such as Bowen's disease and extramammary Paget's disease, leukemia, lymphoma, syphilitc fissures, and tuberculous ulcer. Such patients must be referred for a diagnostic biopsy of the ulcer edge, culture of the anal canal, and a systemic evaluation.
Most often, the traditional midline anal fissure is caused by the trauma produced by the passage of a particularly hard and large fecal mass, but it is also seen after acute episodes of diarrhea. Fissures persist because of the severe, chronic internal sphincter spasm that occurs along with the secondary infection of its base.
Was this article helpful?
This guide will help millions of people understand this condition so that they can take control of their lives and make informed decisions. The ebook covers information on a vast number of different types of neuropathy. In addition, it will be a useful resource for their families, caregivers, and health care providers.