Fistulas and Fistula Surgery

An ANAL FISTULA (also called fistula in ano) is an abnormal connection (think of a small tunnel) between the rectum or anus (the lowest part of the bowel near your buttocks where stool passes from) and the skin around the anus.  Anal fistulas most commonly develop after someone has had an abscess. 

We all have anal glands that exist between our two sets of anal control muscles called the anal sphincters.  The anal sphincters are two circles of muscle (think of a smaller donut within a larger donut) that circle the anus and act to help us control our bowels so that we don’t soil ourselves when we are up and walking around or when we cough, sneeze, laugh, or strain.  These anal glands make lubricant that travels down a small duct (drainage tube) that empties out into the anal canal and helps to lubricate our stool.

Sometimes these anal glands and their duct (drainage tube) become blocked and infection sets in.  The infection looks for the easiest way to escape, and often develops into a pocket of infection called an abscess. This is typically quite uncomfortable.  The abscess often works its way out to the skin and when it bursts or is drained, there is now a connection from the outside skin through to the infected anal gland and through the anal gland duct to the inside of the anal canal.  If the area does not fully heal and scar down, but instead a connection remains, then this is an ANAL FISTULA.

The hallmark symptoms of an anal fistula are continued discharge or leakage from the buttocks or area by the anus, or a cycle of the skin healing over, then buildup of infection with pain, swelling, or redness, followed by the area bursting and draining.  As the body wants to heal, this cycle often repeats.

The challenge in treating an ANAL FISTULA is that we do not want to do anything to injure the anal sphincters that give us control of our bowels.  It is very effective treatment for the fistula to just cut the fistula right open, however doing this might mean cutting the sphincter muscles and damaging control of gas and stool.

If there is too much muscle involved to cut, we use a number of strategies and surgery approaches to treat anal fistulas that work to avoid damage to the sphincter muscles.  To avoid damage to the anal sphincter we use a step by step approach, and it often takes multiple procedures over a number of months to successfully treat a fistula.  The first step is typically to place a small rubber band called a draining seton into the fistula tract to break the cycle of healing, infection, buildup, and drainage.  This will not stop the drainage but will help to decrease the inflammation in that area.  This rubber band seton stays in place for about 3 months and at that point we plan a second procedure which attempts to close the fistula while avoiding any damage to the sphincter.

Alternately, we sometimes place a string of stitch called a cutting seton.  This works its way through the tissue so slowly that it allows healing to occur at the same time, decreasing the chance of serious damage to the sphincter muscles.

After a cutting seton has done it’s work there may be little tissue left allowing us to just cut the last little bit.  If there is a lot of muscle involved and a draining seton has been in place, the second procedure to close off the fistula is usually either called a LIFT (Ligation of intersphincteric fistula tract) or an endoanal advancement flap. 

In the LIFT procedure, a small incision is made in between the two circular sphincter muscles being careful not to damage or divide any of the muscle.  The fistula tract (tunnel) is dissected out, sutured shut, and divided (cut).  The incision is then stitched closed.  A wound is also made on the buttocks where the fistula was draining to remove any further infection.

In the endoanal advancement flap procedure, a flap of healthy tissue from within the anus above the fistula is lifted up and then pulled down to close over the internal opening and stitched in place.  A wound is again made on the buttocks where the fistula was draining to help remove any infection.

Unfortunately, neither of these procedures are 100% successful, but both have the advantage that they are designed to protect the anal sphincters from any damage.  These procedures in published studies are about 60-70% successful, and if one procedure fails you may have the option to try again with the same procedure or the alternate procedure.

Risks of surgical procedures for ANAL FISTULA include the risk of a bad reaction or complication from anesthesia, bleeding, infection, poor healing, failure of the procedure, or injury to the anal sphincter muscles despite attempts to protect them during surgery. Injury to the anal sphincter muscles can result in a change in control of gas or stool.