A fistula is an abnormal communication between a hollow viscus and some other organ or structure, including the skin. To be classified as such, it is understood that the communication remains open for long enough to present a clinical problem. Some fistulas are complex, with multiple tracts and associated abscess cavities. Others are simple and heal spontaneously. The subject of this chapter is fistulae originating in the duodenum, jejunum, or ileum.

There are several ways to classify fistulae and these are useful in selecting measures for management and for comparison of therapeutic approaches. The first is descriptive, and includes the sites of origin and termination: examples are jejunocutaneous or ileovesical fistulas. A second classification is internal versus external; internal fistulae include ileocolic or ileoileo fistulae; external fistulae include duodenocutaneous or ileovaginal. Thirdly, external fistulae can be classified by output. A useful practical separation is into low output fistulae that produce less than 200 ml of discharge per day and high output fistulae that discharge more than that amount. Finally, it is helpful to classify fistulae into those originating from normal intestine and those associated with an abnormality such as Crohn's disease or radiation enteritis.

Almost all external fistulae develop as an early complication following surgical procedures. A few of these are the result of technical errors in bowel anastomoses or repair; more frequently, they result from sepsis in the region of a suture line. In either case, they present as an abscess draining through the recent incision followed by the establishment of a fistula. A few external fistulae occur at the site of an old surgical incision, and are associated with a foreign body, usually mesh used in the repair of a fascial defect, recurrence of inflammatory bowel disease, or a tumour. Rarely, external fistulae are spontaneous and occur at the site of drainage of an abscess originating from a bowel perforation. These can be caused by a tumour or inflammatory bowel disease.

Internal fistulae differ in that they seldom follow a surgical procedure, but are usually the result of a local perforation of diseased bowel. An abscess forms that affects an adjacent structure. In most cases this is a loop of small intestine or colon but it can be part of the urinary tract or even the biliary system.

Spontaneous rapid closure of fistulae is seen regularly on removal of a draining or feeding tube from the duodenum or jejunum. This rapid healing can be expected when the fistula originates from normal intestine, is made up of a narrow cicatricial tract, and is not associated with active sepsis. There must also be a satisfactory capability for normal healing, which implies an adequate nutritional status.

The factors contributing to failure of spontaneous closure are largely implied in the foregoing paragraph. They include origin of the fistula in abnormal intestine, such as a segment involved by Crohn's disease, radiation enteritis, or a tumour. Other intrinsic factors preventing spontaneous healing are an extensive defect in the intestine, such as dehiscence of a suture line or the presence of distal obstruction.

The absence of a narrow cicatricial tract is frequently the result of local sepsis. Thus, the internal intestinal opening empties into a cavity or cavities which then drains through the abdominal wall. The presence of a foreign body may prevent the local control of sepsis and the formation of such a tract. Finally, the junction of mucosa of the intestine with that of another loop of intestine or the skin can prevent healing. This is an especially important factor in internal fistulae.

In patients severely depleted by an underlying illness or chronic fluid and electrolyte losses, healing also may be impaired. In the chronically ill patient, a loss of 15 per cent of body weight and a low serum albumin furnish useful clues to the specific need for extra nutritional support.

Measures to decrease fistula output not only simplify management, but also allow more rapid closure and simplify the management of skin inflammation and erosion.

The basic steps in the management of fistulae are outlined in Table 1 315. Experience and judgement are important in reaching decisions about the need and timing of surgical intervention. The goal is to achieve permanent closure of the fistula in the shortest time and with the lowest possible risk to the patient. Individual management based on sound principles is the key.

Some patients with fistulae present with serious acute problems that include fluid and electrolyte depletion and uncontrolled sepsis. Aggressive management to correct these decreases the chance of secondary complications such as renal failure and metastatic sepsis. The measures to be employed do not need further discussion here.

Prevention of skin breakdown is much easier than its management: sump catheters may be required for the management of a large wound. Later a collecting bag should be used as a means for protecting the skin and quantitating output. The assistance of an enterostomal therapist or nurse skilled in the various possible approaches to this is ideal, but devoted nursing care is the major element in success.

Once these two steps have been accomplished, studies should be undertaken to determine the site of origin of the fistula, the condition of the intestine at that point, and whether there is an associated abscess cavity. Generally, a fistulogram, using a water soluble radio-opaque medium, is a good first choice, perhaps combined with an ultrasound study or CT scan. If there is no cavity, barium studies can then be used to gain further detail and to opacify the intestine at and below the fistula. Orally administered barium will usually give the most information, including information about the size of the leak, the absence of distal obstruction and the presence of a tumour, or extent of inflammatory changes in the intestine itself.

Steps to decrease fistula output may simplify management and increase the rate of spontaneous closure. The initial measure is the placement of a nasogastric tube or if long-term use may be indicated, a gastrostomy tube. Sometimes this can be placed at the time of another operative procedure. The nasogastric tube is, however, a cause of discomfort, and it can increase the tendency toward aspiration and pulmonary sepsis in older and debilitated patients and may also induce an oesophageal stricture. Pharmacological means of decreasing output include the administration of H&sub2; blockers without antacids and somatostatin analogues.

The status of the patient or anticipation of a long period of starvation may indicate a need for nutritional support. Central parenteral hyperalimentation will allow the intestinal tract to be placed completely at rest. This has special benefits in the patient with Crohn's disease, in whom regression of the extent and severity of the disease is commonly observed. A few fistulae in such patients may actually heal simplifying later surgical intervention.

A second approach uses elemental diets. These can be completely absorbed and require no digestion. They are poorly tolerated orally because they are so unpalatable but can be instilled through a small nasogastric feeding tube, a gastrostomy tube or a jejunal feeding tube. Continuous rather than bolus infusion is better tolerated. They are most useful in patients with a very distal fistula or in those who have a feeding tube in place distal to a proximal fistula.

Finally, especially with a low output fistula, oral feedings are sometimes well tolerated. The output of the fistula should be monitored. If it is not much increased by eating, this can provide the least expensive and safest form of nutritional support.

Early surgical intervention usually involves only measures to gain better control of the fistula and increase the likelihood of spontaneous closure. In addition to the placement of draining and feeding enterostomy tubes, this includes steps to promote the formation of a single narrow drainage tract. Abscess cavities must be unroofed or drained and placing a catheter adjacent to or even in a fistula opening may be useful. Simple closure of the fistula opening with sutures at this stage is, however, almost certain to fail.

The definitive treatment of fistulae that do not close spontaneously is surgical resection. Most external fistulae associated with Crohn's disease require such treatment. In almost all cases a segment of intestine is removed with anastomosis, the sutured bowel being placed in an area not affected by inflammation or other abnormality. A bypass may be all that can be accomplished. Duodenal fistulae are an exception: segmental resection is seldom feasible, and the surgical measure most likely to succeed is Roux-en-Y limb anastomosed over the fistula, converting it to a permanent internal fistula (Fig. 1) 979. If direct closure seems possible, the suture line should be protected by bringing up a loop of intact small intestine as a ‘serosal patch’. This condition meets the need of providing a normal local environment for healing.

Timing of surgical intervention requires judgement and experience. Factors that enter into the decision are size and location of the fistula, condition of the patient, nature and extent of intestinal abnormality, presence of obstruction, fistula output, and likelihood of eventual spontaneous healing. The surgeon must also consider the likelihood of accomplishing a satisfactory operation. The acute obliterative peritonitis that follows complicated operations is likely to be an important factor in reoperation between 10 days and 6 weeks after the original operation. The tendency at the present time is to delay too long rather than operate too soon. Medical management has largely eliminated the necessity for urgent resection of fistulae but can also contribute unnecessarily to the period of disability and expense by lengthening the stay in hospital.

These fistulae drain small amounts of fluid, arbitrarily up to 200 ml/day. The drainage often has the appearance of mucous or infected material that does not suggest an intestinal origin. Acute low output postsurgical fistulae are the result of trivial injuries to the intestine, as in closing the abdominal wall or a small leak from an intact bowel anastomosis or repair, and almost always heal spontaneously. Obtaining adequate local drainage and a short period of parenteral fluid support facilitates closure.

Persistence of a low output fistula usually indicates the presence of a foreign body, typically heavy sutures or mesh, or an intrinsic abnormality of the intestine at the site of origin. The use of fine absorbable suture material can prevent some of these fistulae. Synthetic mesh that comes in contact with a segment of intestine eventually causes perforation, an abscess, and, typically, a low output chronic fistula. Sometimes only part of the mesh need be removed to secure healing: removal of all of the mesh creates the difficult additional problem of dealing with the resulting fascial defect at the time of operation.

The lack of urgency in the setting of a low output fistula allows complete evaluation of the intestine proximal and distal to the site of origin. The management of Crohn's disease, other inflammatory conditions, radiation enteritis, and tumours is usually not specifically altered by the presence of the fistula. Other factors dictate the timing and nature of surgical intervention.

The presence of a high output fistula usually indicates either the diversion of a substantial part of the intestinal contents or a very proximal origin, and many patients have partial or complete obstruction or extensive suture line dehiscence. The likelihood of sepsis, extensive skin breakdown, and problems related to fluid loss and nutritional depletion increases with output. Successful management centres on the methodical application of measures already described, and there is seldom need for urgent direct surgical intervention. Some high output fistulae heal spontaneously, but many will be best managed by an elective resection under optimal conditions. The principles important to successful surgery have already been listed. The fact that local closure with limited exposure seldom succeeds is worth emphasis: the operation should be broad enough in scope to achieve an optimal repair. It is often better to enter the abdomen through a new incision and to begin by exposing the uninvolved loops of intestine. Patience and skill in dissection are needed. Any intestinal suture line must be placed in contact with normal serosal surfaces: leaving it in an area of chronic inflammation invites formation of a new fistula. Wide exposure will facilitate accomplishment of this objective and permits management of multiple fistulae or residual pockets of infection. Drains should be avoided unless considered absolutely necessary. Consideration should be given to the placement of draining gastrostomy and feeding jejunostomy tubes in complicated cases.

Internal fistulae are almost always the result of chronic inflammation of the intestine. Perforation and abscess formation leads to communication with an adjacent loop of bowel or viscus. A few fistulae follow trauma or surgical misadventures.

Ileoileal and ileocolonic fistulae are relatively harmless and often asymptomatic—obstruction or sepsis rather than the fistula itself are the usual reasons for resection. Fistulae to the bladder or, rarely, to other parts of the urinary system, lead to recurrent bouts of urinary sepsis; for this reason they usually require resection. Duodenocholedochal fistulae, a rare complication of duodenal ulcer disease, are often asymptomatic, but may lead to episodes of biliary sepsis.

The first principle in management is to resect the segment of diseased bowel that gave origin to the fistula. Unless the intestine or viscus at the other end of the fistula is intrinsically diseased, a resection is not necessary. When the duodenum is the site, as in an ileoduodenal fistula from Crohn's disease, the closure should be buttressed with a loop of normal intestine. Simple closure is sufficient for fistulae to the vagina, uterus, or urinary bladder.

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