Anal fissure


The anus is the external opening of the rectum (the final portion of the colon). A rip or tear in the skin of the anal canal is called an anal fissure. Anal fissures may result in anal bleeding, which is noticeable on toilet paper or in stool in the toilet. Pain is associated with both acute and chronic anal fissures. In general, the fissures extend from the anal opening and are located posteriorly in the midline. The depth of the fissure varies; it may be superficial or as deep as the underlying sphincter muscle (the muscle that holds the anus closed). An anterior fissure is very rare (10% of female and 1% of male cases).
Anal fissures are generally caused by stretching of the anal mucosa (moist tissue). This may occur because of constipation, passing hard and/or large stools, prolonged diarrhea, decreased blood flow to the area (as seen occasionally in older adults), childbirth, dietary choices, or inflammatory bowel disorders such as Crohn's disease. Anal fissures occur commonly in infants. Less common causes include anal sex and diseases such as cancer, HIV, tuberculosis, and syphilis.
The drug nicorandil (a potassium-channel activator) may increase the risk of anal fissure, although the available research is limited.
Anal fissures may affect all age groups, with an equal incidence in both sexes. In the United States, over 200,000 new cases of anal fissure are reported, and 40% persist for months to years. In pregnancy, up to one-third of women develop anal fissures and external hemorrhoids. Constipation and dyschezia (retaining stool in the rectum) during pregnancy are the main risk factors for their development.
Of current interest is the development of surgical treatments with fewer complications than lateral internal sphincterotomy (LIS), the current treatment of choice for chronic fissures. LIS generally has a high success rate. However, complications may include postsurgical pain, slow healing of the incision, and development of acute (during the surgical recovery period) and usually mild anal incontinence (lack of control of the bladder), including the inability to control gas, fecal soiling, and fecal loss.

Related Terms

Abrasions, acute anal fissure, anal cancer, anal crack, anal fistula, anal pain, anal tear, anal ulcer, bariatric procedures, chronic anal fissure, constipation, Crohn's disease, dehydration, diarrhea, hemorrhoids, incontinence, infected surgical wounds, inflammatory bowel disease, inflammatory phase, laceration, perianal abscess, perianal fistula, pregnancy, primary anal fissure, rectal ulcer, secondary anal fissure, skin wounds, thrombosed external hemorrhoids, wound care, wound healing.

types of the disease

General: Both acute and chronic anal fissures are possible. Fissures may be considered primary (with no known trigger) or secondary (there is a likely trigger).
Acute vs. chronic anal fissures: Acute anal fissures are commonly associated with severe pain after defecation. Acute anal fissures are generally superficial or shallow and may be hard to detect visually. Acute fissures generally heal within days to weeks. Chronic anal fissures, lasting longer than about six weeks, are generally associated with less pain than the acute form of the disorder. These anal fissures become deeper (forming an ulcer), and healing is more difficult or does not occur. Internal anal sphincter muscle spasm impairs blood supply to the fissure, reducing the ability to heal. In the case of a chronic, nonhealing ulcer, infection by fecal bacteria is possible.
Primary vs. secondary anal fissures: Primary anal fissures are most commonly located on the posterior anal midline and have no obvious trigger. A small percentage of primary anal fissures are located on the anterior midline. Secondary anal fissures are a result of inflammatory bowel disease, previous anal surgery, and disease (e.g., venereal diseases, skin disorders, infections, or tumors). Infections associated with secondary anal fissures may include tuberculosis, herpes, cytomegalovirus, Chlamydia, Haemophilus ducreyi, and HIV. The location of secondary anal fissures may not be typical (lateral, etc.).