A fistula is an abnormal communication between two hollow organs. Such fistulae can be internal, or external. Internal fistulae communicate with another loop of bowel, such as an enteric fistula between two loops of small bowel, or another organ, such as bladder (colovesical fistula) or vagina (sigmoidovaginal fistula). External fistulae typically communicate with the skin, such as a colocutaneous (between colon and skin) or enterocutaneous (small bowel and skin) fistulae.
Who is at risk:
Fistulae are rarely spontaneous and are typically due to complications of other disease processes and therefore can affect a number of different patients. Fistulae can be due to complications of diverticular disease, inflammatory bowel disease (specifically Crohn’s disease), radiotherapy, foreign body/mesh, cancer and trauma or iatrogenic injuries.
What are the symptoms:
Patient presenting with “cutaneous” fistulae have a non-healing, area of the skin with persistent discharge. The volume and consistency of discharge is dependent on the area of bowel that acts as the fistula source. High output fistulae are those that secrete more than 500ml per day, while low output fistulae secrete less than 200ml. In patients who have not been appropriately assessed symptoms may be debilitating due to severe skin irritation, dehydration and psychological distress.
Internal fistulae may result in diarrhea and malabsorption, as well as faeces and/or gas per vagina or upon urination.
How are fistulas diagnosed:
The diagnosis is based on the combination of patient history and physical examination. Sometimes an examination under anaesthesia (with patient asleep in the operating room) is required to confirm the site of the fistula, particularly if this involves the colon, bladder or vagina.
What is the treatment of enteric fistulae:
Treatment of enteric fistulae is unique to the individual patient and the fistula. The management is often multifactorial and labour intensive, therefore should only be offered in a well-resources centre with a multidisciplinary, experienced team.
The management of fistulae is multifactorial.
- Correction of nutritional deficits with appropriate supplementation
- Treatment of infections with antibiotics and/or drainage of collections
- Skin protection with barrier dressings (assisted by stoma nursing)
- Psychological evaluation and support due to significant distress caused by the condition
- Investigation of the aetiology (cause) and anatomy (pathway)
- Radiological and endoscopic evaluation of the gastrointestinal tract
- Definitive surgery
Fistulas that have not closed within six weeks of diagnosis are unlikely to close spontaneously. Fistula surgery is difficult, requires major surgery and should only be performed by experienced surgeons. Typically, a delay of 6 months is optimum prior to attempt at fistula repair.