An anal fissure is an unnatural crack or tear in the anus skin. As a fissure, these tiny tears may show as bright red rectal bleeding and cause severe periodic pain after defecation.^[1] The tear usually extends from the anal opening and located posteriorly in the midline. This location is probably because of the relatively unsupported nature of the anal wall in that location.

Causes

Most anal fissures are caused by stretching of the anal mucosa beyond its capability. Various causes of this fissure include:

• Straining to defecate, especially if the stool is hard and dry
• Severe and chronic constipation
• Severe and chronic diarrhea
• Crohn's disease and Ulcerative colitis
• Tight sphincter muscles
• Anal intercourse
• Anal Probing

Many acute anal fissures will heal spontaneously. Some fissures become chronic and will not heal. The most common cause for this is spasm of the internal anal sphincter muscle. This spasm causes poor blood flow to the anal mucosa, hence producing an ulcer which does not heal since it is deprived of normal blood supply.

Anal fissures are common in women after childbirth,^[2] and following constipation in infants.^[3]

Prevention

In infants under one year old, frequent diaper change can prevent anal fissure. For adults, the following can help prevent fissure:

• Treating constipation by eating food rich in dietary fiber, avoiding caffeine (which can cause dehydration), drinking a lot of water and taking stool softener.
• Treating diarrhea promptly.
• Lubricating the anal canal with KY Jelly or other water-based lube before inserting anything (ex: vibrator, penis) into your anal canal.(petroleum jelly is not recommended because it can harbor harmful bacteria).
• Avoiding straining or prolonged sitting on the toilet.
• Using a moist wipe instead of perfumed and harsh toilet paper.
• Keeping the anus dry and hygienic.
• When using Analpram (cream) do not use the dispenser which can injure the area. Instead use a finger to insert a pea size amount of cream.
• Carmex lip ointment (the version without sunscreen-protection chemicals) also helps and is much less expensive than Analpram ($70.00 small tube).

Treatment

For many years up until 1995, customary treatment included warm baths, topical anesthetics, stool bulking agents, mechanical anal stretching, and, sometimes, surgery.^[1] In 1995, doctors began using nitroglycerine cream (topical 1 percent isosorbide dinitrate) but found it less acceptable for long-term use due to patients developing a tolerance to the drug.^[1] In 1998, Italian researchers reported injecting botulinum toxin into the anal sphincter to promote healing by relieving anal spasm through relaxation of the muscle.^[1]

Symptomatic

Most anal fissures are shallow or superficial (less than a quarter of inch or 0.64 cm deep). These fissures self-heal within a couple of weeks. Furthermore, treatment used for hemorrhoid such as eating a high-fiber diet, using stool softener, taking pain killer and having a sitz bath can help.

Pediatric

Anal fissures in infants usually self-heal without anything more than frequently changing diapers and treating constipation if the cause.

Chemical sphincterotomy

Painful deep chronic fissures, on the other hand, will not heal because of poor blood supply caused by sphincter spasm. Traditionally surgical operations were required which are both painful and associated with various longterm complications, particularly incontinence in a small proportion of cases. Local application of medications to relax the sphincter muscle, thus allowing the healing to proceed, was first proposed in 1994 with nitroglycerine ointment,^[4][5][6] in 1999 with nifedipine ointment,^[7][8] and the following year with topical diltiazem.^[9] Branded preparations are now available of topical nitroglycerine ointment (Rectogesic as 0.2% in Australia and 0.4% in UK) and diltiazem 2% (Anoheal in UK although still in Phase III development).

Botulinum toxin injection, administered by colorectal surgeons, can also be used to relax the sphincter muscle and its use for this condition was first investigated in 1993.^[10] Combination of medical therapies may offer up to 98% cure rates,^[11] These medical treatments are used as first line therapy in treating chronic anal fissures,^[12] although a Cochrane Collaboration review of published research has questioned the effectiveness of medical treatments compared to surgery.^[13]

Surgical sphincterotomy

Surgical intervention may be required for persisting deep anal fissures unresponsive to the above conservative measures. Procedures include:

• Internal lateral sphincterotomy or excising a portion of the sphincter
• Anal dilation or stretching of the anal canal is no longer recommended because of the unacceptably high incidence of fecal incontinence.^[14] In addition, anal stretching can increase the rate of flatus incontinence.^[15]

Despite the high success rate of these surgical procedures (~95%), there are potential side effects, which include: risks from anesthesia, infection and anal leakage (fecal incontinence). 

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