An anal fissure is a break or tear in the skin of the anal canal. Anal fissures may be noticed by bright red anal bleeding on toilet paper and undergarments, or sometimes in the toilet. If acute they are painful after defecation, but with chronic fissures, pain intensity often reduces. Anal fissures usually extend from the anal opening and are usually located posteriorly in the midline, probably because of the relatively unsupported nature and poor perfusion of the anal wall in that location. Fissure depth may be superficial or sometimes down to the underlying sphincter muscle. Untreated fissures develop a hood-like skin tag (sentinel piles) which cover the fissure and cause discomfort and pain.
Causes
Most anal fissures are caused by stretching of the anal mucous membrane beyond its capability.
Superficial or shallow anal fissures look much like a paper cut, and may be hard to detect upon visual inspection; they will generally self-heal within a couple of weeks. However, some anal fissures become chronic and deep and will not heal. The most common cause of non-healing is spasming of the internal anal sphincter muscle which results in impaired blood supply to the anal mucosa. The result is a non-healing ulcer, which may become infected by fecal bacteria. In adults, fissures may be caused by constipation, the passing of large, hard stools, or by prolonged diarrhea. In older adults, anal fissures may be caused by decreased blood flow to the area. When fissures are found laterally, tuberculosis, occult abscesses, leukemic infiltrates, carcinoma, acquired immunodeficiency syndrome (AIDS) or inflammatory bowel disease should be considered as causes. Some sexually transmitted infections can promote the breakdown of tissue resulting in a fissure. Examples of sexually transmitted infections that may affect the anorectal area are syphilis, herpes, chlamydia and human papilloma virus.
Other common causes of anal fissures include: childbirth trauma in women anal sex Crohn's disease ulcerative colitis poor toileting in young children.
Diagnosing
External anal fissures on the anal verge can be diagnosed by visual inspection.
Internal anal fissures in adults on anterior side, posterior side or within any part of the inner circumference of the anal sphincter muscle can be diagnosed with beak proctoscope 23mm diameter, Chelsea Eaton anal speculum 23mm diameter, Park anal retractor or by digital rectal examination with a finger inside the anal sphincter muscle. Narrow anal fissures might not be felt by finger during rectal examination due to the glove.
Note that colonoscopy, sigmoidoscopy, or normal proctoscopy is for diagnosing internal hemorrhoids and other internal rectal diseases and not for diagnosing anal fissures.
Prevention
For adults, the following may help prevent anal fissures: Avoiding straining when defecating. This includes treating and preventing constipation by eating food rich in dietary fiber, drinking enough water, occasional use of a stool softener, and avoiding constipating agents. Similarly, prompt treatment of diarrhea may reduce anal strain. Careful anal hygiene after defecation, including using soft toilet paper and cleaning with water, plus the use of sanitary wipes. In cases of pre-existing or suspected fissure, use of a lubricating ointment (It is important to note that hemorrhoid ointment is contraindicated because it constricts small blood vessels, thus causes a decrease in blood flow, which prevents healing).
In infants, frequent diaper change can prevent anal fissure. As constipation can be a cause, making sure the infant is drinking enough fluids (i.e. breastmilk, proper ratios when mixing formulas) is beneficial. In infants, once an anal fissure has occurred, addressing underlying causes is usually enough to ensure healing occurs.
Treatment
Non-surgical treatments are recommended initially for acute and chronic anal fissures. These include topical nitroglycerin or calcium channel blockers (e.g. diltiazem), or injection of botulinum toxin into the anal sphincter.
Other measures include warm sitz baths, topical anesthetics, high-fiber diet and stool softeners.