Enterocutaneous Fistula

Figure:Enterocutaneous fistula

An external fistula communicating with the gut mucosa to the skin surface. It may occur following an operation for gangrenous appendicitis or the draining of the appendix abscess. A faecal fistula can occur from necrosis of a gangrenous patch of intestine after the relief of a strangulated hernia, or from a leak from an intestinal anaestomosis. The opening of an abscess connected with chronic diverticulitis or carcinoma of the colon frequently results in faecal fistila. Radiation damage is also another cause of faecal fistula. The most common cause of cutaneous fistula is however previous surgery. This happens most often in patients with adhesions following previous operations. Enterocutaneous fistula can be divided into:-

1)       Those with a high output, more than 1 L/day

2)        Those with a low output, less than 1 L/ day.

They can also be describe anatomically as simple, with a direct communication between the gut and the skin, or complex, i.e. those with one or more tracts they are tortuous and sometimes associated with an intervening abscess cavity half way along the tract.

The discharge from a fistula connected with the duodenum or jejunum is bile stained and causes severe excoriation of the skin. When the ileum or caecum is involved is involved, the discharge is fluid faecal matter; when the distal colon is the affected site, it is solid or semisolid faecal matter. The site of the leakage and the length of the fistula can be determined by small bowel enema and Ba-enema, by fistulogram and more importantly, by CT scan of the abdomen will show up any associated abscesses.

Treatment

                     This can be very challenging in patients with a high output fistula. Low output fistula can be expected to heal spontaneously, provided that there is no distal obstruction. Reasons for failure of spontaneous healing also include:

1)        epithelial continuity between the gut and the skin;

2)        the presence of active disease where, for example there is crohn’s disease or carcinoma at the site of anaestomosis or in the tract;

3)        an associated complex abscess.

The abdominal wall must be protected from erosion by the use of appliances. The patients must remain nil by mouth; intravenous nutrition is started and signs of a decrease in fistula output are sought. The higher the fistula in the intestinal tract, the more skin excoriation must be expected, and this is worst in the case of a duodenal fistula. High output fistula cause rapid dehydration and hypo-proteinaemia. Vigorous fluid replacement  and nutritional support is essential. The drainage of an intra-abdominal abscess can be life saving. This can be achieved by either CT guided drainage or occasionally laparotomy. In patients with a complex  fistula, it may be necessary to bring out a de-functioning stoma upstream of the fistula site, even if this result in a high output stoma.    

 Operative treatment  

                                        Operative repair should be attempted only after a trial of conservative management. The surgery can on occasion be extremely technically demanding and an anaestomosis should not be fashioned in the presence of continuing intra-abdominal sepsis or when the patient is hypo proteinaemic.