Fistula in ano (anal fistula)

Anal fistula, or fistula-in-ano, is an abnormal connection between the surface of the anal canal and the perianal skin. Anal fistulae originate from the anal glands, which are located between the two layers of the anal sphincters and which drain into the anal canal. If the outlet of these glands becomes blocked, an abscess can form which can eventually point to the perianal skin surface. The tract formed by this process is the fistula. Abscesses can recur if the fistula seals over, allowing the accumulation of pus. It then points to the surface again, and the process repeats.

What are the related symptoms of anal fistulas?

Anal fistulas per se are not harmful but can be very painful and can be irritating because of the continuous drainage of pus. Additionally, recurrent abscesses may develop. Signs and symptoms of an anal fistula include:

• Swelling and pains around the anus
• Foul-smelling or bloody drainage of pus from an opening near the anus. The pain may decrease after the anal fistula drains.
• Skin irritation around the anus from drainage
• Pain during bowel movement
• Bleeding
• Chills, fever and fatigue

How are anal fistulas treated?

Dr Cooper will perform surgery to drain the acute abscess. Repair of the anal fistula itself is considered an elective procedure that many patients elect to undertake due to the discomfort and inconvenience associated with the draining tract.

There are several surgery options, such as:

• Seton stitch
  Dr Cooper may insert a length of suture material or a thin rubber band looped through the fistula which keeps it open and allows the pus to drain out. In this situation, the Seton is referred to as a draining Seton. A drainage Seton can be left in place long-term to prevent problems. This is the safest option, although it does not definitively cure the anal fistula.
• Lay-open of fistula-in-ano
  this option involves Dr Cooper cutting the anal fistula open. Once the fistula has been laid open, it will be packed on a daily basis for a short period of time to ensure that the wound heals from the inside out. This option leaves behind a scar, and depending on the position of the anal fistula in relation to the sphincter muscle, can cause problems with incontinence. This option is not suitable for fistulas that cross the entire anal sphincter.
• Cutting seton
  if the fistula is in a high position and it passes through a significant portion of the sphincter muscle, a cutting seton may be used. The seton is tightened over time, gradually cutting through the sphincter muscle and healing as it goes. This option minimizes scarring but can cause incontinence in a small number of cases, mainly of flatus (wind). Once the fistula tract is in a low enough position, it may be laid open to speed up the process, or the seton can remain in place until the fistula is completely cured.
• Colostomy
  to allow healing in severe cases (usually where Crohn's disease is present). During this procedure, Dr Cooper will bring out one end of the large intestine through the abdominal wall to create a stoma where a stoma bag / pouch for collecting faeces will be attached.
• Fibrin glue injection
  is a method explored in recent years, with variable success. It involves the surgeon injecting the fistula with a biodegradable glue which should, in theory, close the fistula from the inside out, and let it heal naturally. This method is best tried before all others, if successful; it may avoid the risk of incontinence, and creates minimal stress for the patient.
• Fistula plug
  involves plugging the fistula with a device made from pig small intestinal submucosa. The fistula plug is positioned from the inside of the anus and fixed with a suture. According to some sources, the success rate with this method is as high as 80%. As opposed to the staged operations, which may require multiple hospitalisations, the fistula plug procedure requires hospitalisation for only about 24 hours.
• Endorectal advancement flap
  is a procedure in which the internal opening of the fistula is identified, and a flap of mucosal tissue is cut around the opening. The flap is lifted to expose the fistula, which is then cleaned and the internal opening is sewn shut. After cutting the end of the flap on which the internal opening was, Dr Cooper will pull the flap down over the sewn internal opening and sutured in place. Success rates are variable, and recurrence rates are directly related to the amount of previous attempts to correct the fistula.
• LIFT Technique
  is a novel modified approach through the intersphincteric plane for the treatment of fistula-in-ano, known as LIFT (Ligation of Intersphincteric Fistula Tract) procedure. LIFT procedure is based on secure closure of the internal opening and removal of infected glandular tissue through the intersphincteric approach. Essential steps of the procedure include incision at the intersphincteric groove, identification of the intersphincteric tract, ligation of intersphincteric tract close to the internal opening and removal of intersphincteric tract, scraping out all granulation tissue in the rest of the fistulous tract, and suturing of the defect at the external sphincter muscle.