Laboratory Studies
If an ordinary anal fissure is suggested and if it is located in the posterior or anterior midline, then no laboratory tests are necessary.
If the fissure is off the midline or irregular, or if an underlying illness (eg, Crohn disease, squamous cell cancer, or AIDS [4] ) may be present, then the appropriate tests should be ordered; these may include the following:
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Erythrocyte sedimentation rate (ESR)
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Stool and viral cultures
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HIV testing
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Biopsy of the lesion or fissure (as warranted)
Diagnostic Procedures
The diagnosis of anal fissure can usually be made on the basis of findings from a gentle perianal examination with inspection of the anal mucosa, in conjunction with a good history. In this case, no diagnostic procedures are required. A digital rectal examination (DRE) is painful and often can be deferred.
Occasionally, the fissure is not easily visualized, and anoscopy is required to see it. However, anoscopy is not well tolerated by a patient with an acute anal fissure, and the procedure can often be deferred, with the patient treated solely on the basis of symptoms. Occasionally, a topical application of 1-2% lidocaine facilitates the examination.
Patients who do not heal, those who have relief from symptoms with appropriate therapy, or those who have a recurrent anal fissure after surgical therapy should be evaluated further with anoscopy and rigid proctosigmoidoscopy to exclude other pathologies. Patients with chronic fissures tend to have less pain and can better tolerate either anoscopy or rigid proctosigmoidoscopy and should have this included in their evaluation.
Histologic Findings
The fissure is not usually excised; therefore, no pathology specimen is available for examination. When it is excised, the tissue typically exhibits nonspecific inflammation. If some of the muscle is accidentally excised with the fissure, the internal sphincter usually demonstrates fibrosis.
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Acute anal fissure.
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Anal fissure.
