Anal fissure

An anal fissure (also called a fissure-in-ano) is a crack in the very specialized lining (anoderm) of the anal canal.  The crack is most often in the midline of the back of the anus (towards the tailbone) but may also be in the midline of the front of the anal canal.  Most patients think that a fissure is a result of a tear from a large bowel movement.  This is not correct.  The anal canal is one of the fastest healing parts of the body.  If a fissure were really just a tear, it would heal within a day or so.  So why do fissures often persist for months or years?  This is because the true cause of fissures is an abnormality in muscle function of the involuntary sphincter muscle (internal sphincter) that surrounds the anal canal.  If the internal sphincter muscle contracts too much (excessive muscle tone), the pressures in the anal canal rises and this probably interferes with normal blood flow within the anal canal and leads to cracking of the anal canal (fissure).

Anal fissures are usually painful.  They can hurt during a bowel movement (sharp pain), and they may hurt for hours after a bowel movement (burning, deep aching sometimes throbbing pain).  The pain during the bowel movement is from the fissure reopening.  The pain that follows the bowel movement is from underlying internal sphincter muscle spasm.  Not all patients have pain following a bowel movement, only those with more severe fissures.

In addition to being painful, fissures can be itchy (sometimes incredibly itchy), and they can bleed.  When a fissure bleeds, it is usually just streaks of bright red blood on the toilet paper.  Less commonly, blood will drip into the toilet bowl.

An anal fissure is often accompanied by a lump on the outer edge of the anus.  This lump is called a ‘sentinel pile’ as it signals trouble beneath it.  When the fissure is acting up, the sentinel pile will often become quite hard and painful and itchy.  Sentinel piles are often mistaken for hemorrhoids.  Patients will frequently say they have a ‘hemorrhoid’ and want it removed.  But a sentinel pile is not a hemorrhoid at all and removing it will do nothing to stop the pain from the underlying fissure.  So, accurate diagnosis is very important here.

Treatment of an anal fissure includes those things that will reduce the pressure within the anal canal.  These include diet changes (hugely important), local muscle relaxants, Botox, and surgery (lateral internal sphincterotomy).

© Pezim Clinic, Vancouver, British Columbia, Canada