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328 Wong et al.
Table 2 Etiology of Acquired Enterocutaneous Fistulas
I. Postoperative occurrence II. Spontaneous occurrence
A. Anastomotic problems A. Intrinsic disease
1. Technical factors 1. Inflammation
a. Tension (inflammatory bowel
b. Blood supply disease, diverticulosis
c. Technique 2. Malignancy
2. Intestinal factors 3. Infection (tuberculosis,
a. Inflammation actinomycosis, amoebiasis)
b. Ischemia 4. Ischemia (embolus,
c. Malignancy thrombosis, low flow)
d. Infection 5. Foreign body
3. Systemic factors 6. Collagen vascular disease
a. Malnutrition 7. Radiation
b. Steroids B. Extrinsic disease
c. Malignancy (including 1. Trauma
chemotherapy and x-ray 2. Other organ
therapy
d. Systemic disease
(diabetes, renal failure)
B. Incidental injury
1. Lysis of adhesions
[l5], a 37% mortality rate in high-output postoperative small bowel fistulas
was seen despite modern supportive therapy.
In a classic paper, Edmunds et al. [16] noted that mortality was related
to three factors: fluid and electrolyte imbalance, malnutrition, and sepsis.
Fluid and electrolyte imbalance is primarily related to fistula output. Ini-
tially 35–40% of patients with fistulas have severe fluid and electrolyte
disturbance and acid-base imbalance [12]. The effluent from high-output
fistulas originating close to the ligament of Treitz is made up largely of
pancreatic and biliary secretions, which contain high concentrations of so-
dium and bicarbonate. As a consequence, fistulas arising in the upper small
bowel are associated with a higher morbidity and mortality and a lower rate
of spontaneous closure than those originating from the large intestine [3].
In a series reported by Fazio et al. [4], the mortality rate for high-output
fistulas was 31%, as opposed to 5% in low-output fistulas.
The importance of malnutrition was demonstrated in 1964 by Chap-
man et al. [17], who found that patients who received <3000 cal/day had a
55% mortality rate, whereas those who received >3000 cal/day had a mor-
tality rate of only 12%. The absence of food intake for several days (espe-
cially during the postoperative period), the hypercatabolism of sepsis with
the breakdown of lean body mass, and the loss of hypertonic protein-rich
secretions from the fistula all contribute to malnutrition. Under normal cir-
Mangagement of Intestinal Fistulas 329
cumstances, the intestinal secretions are digested and the amino acids are
resorbed and resynthesized into protein. When a fistula is present, most of
these secretions are lost.
Uncontrolled sepsis remains the most common cause of death in pa-
tients with enterocutaneous fistulas and contributes to a high rate of associ-
ated complications. In most series it accounts for approximately 70% of all
deaths [3,15,18,19]. Altomare et al. [18] found that 54% of septic patients
died, in contrast to 14% of nonseptic patients. Similarly Reber et al. [7]
described mortality rates of 85% in patients in whom sepsis was uncon-
trolled vs. 8% in patients with controlled sepsis. Such patients are often
postoperative and in a state of immunosuppression from surgery. If there
has been an anastomotic disruption, devitalized tissue is present, forming a
nidus for abscess formation with continued contamination from the gastro-
intestinal tract.
Fistula etiology is also predictive of mortality. Fistulas associated with
malignancy and radiation have a high mortality rate [19,20]. Patients with
fistulas arising from inflammatory bowel disease have a lower mortality rate
[21], yet this rate is higher than that for simple postoperative anastomotic
fistulas (simple type 1), which have the lowest associated mortality [3,4].
Many other factors contribute to the high mortality rate associated
with fistulas. Advancing age has often been related to a higher mortality
rate; however, this connection has not been consistently demonstrated [18].
Many significant risk factors are associated with increasing age, and the
presence or absence of these risk factors may be more important than chro-
nologic age in determining outcome. Patients with malignancy who develop
an unrelated fistula have an increased mortality rate [18,19]. Anemia and
hypoalbuminemia also have been implicated, with associated mortality
rates of 31 and 42%, respectively [18,20]. Perhaps the greatest risk factor
for increased mortality is the presence of an open fistula (complex type 2),
which drains into the base of an incision. Mortality rates in this situation
range from 50–60% and have not improved significantly, even with ad-
vances in supportive care [3,15,20].
In 1989, Levy et al. [2] developed a risk score that correlated eight
so-called severity factors: multiple fistulas, intra-abdominal abscess, septi-
cemia, ileus, adult respiratory distress syndrome, upper gastrointestinal
hemorrhage, renal or hepatic failure, and thromboembolic complications.
They found that any patient with three or more of these factors has a mor-
tality risk of 50%.
REASONS FOR NONCLOSURE
Many factors contribute to the persistence of an intestinal fistula. The most
important of these are (1) undrained sepsis (Fig. 4), (2) distal obstruction
330 Wong et al.
Figure 4 Underlying sepsis, which can be a reason for nonclosure.
(Fig. 5), and (3) underlying disease (e.g., Crohn’s disease, radiation-induced
bowel injury, or malignancy) (Fig. 6). Other potential factors are separation
of the bowel ends (Fig. 7), a short (<2-cm) fistula tract (Fig. 8), a foreign
body, a bowel wall defect >1 cm in diameter, and epithelialization of the
tract (Fig. 9) [22–25]. Reber et al. [7] have reported that in the absence of
mitigating factors, the spontaneous closure rate is 32%. They also stated
Figure 5 Distal obstruction, which may inhibit closure of a fistula.
Mangagement of Intestinal Fistulas 331
Figure 6 Underlying bowel disease, which may be a reason for nonclosure.
that once sepsis has been controlled, 90% of fistulas that close spontane-
ously do so within 1 month. Persistent sepsis, however, affected closure
rate significantly. In those patients whose sepsis was controlled within 1
month, 48% of fistulas closed spontaneously with an 8% mortality, com-
pared to a 6% closure rate and 85% mortality when sepsis was not con-
trolled.
Hugh et al. [26] have stressed that distal obstruction with adhesions
or abscess is a critical factor in fistula persistence. The fistula acts as a
vent, and because the obstruction is usually partial, the diagnosis is often
difficult to confirm. Of 93 patients with colovesical fistula reported on by
Fazio et al., [27] 38 (41%) had persistent distal obstruction as a contribut-
ing factor.
Figure 7 A disrupted anastomosis as a reason for nonclosure.
332 Wong et al.
Figure 8 A short tract may explain failure of a fistula to close spontaneously.
Persistence of underlying disease is responsible for nonclosure of
many fistulas. In a study of enterocutaneous fistulas in patients who under-
went surgery for Crohn’s disease, 6 of 7 patients with no active disease had
closure with conservative management, whereas only 1 of 20 patients with
documented active disease had spontaneous closure [21]. In the series by
Reber et al. [7], when an enteric fistula was associated with Crohn’s dis-
ease, only 8% of fistulas closed spontaneously. When abdominal irradiation
was a factor, only 14% of fistulas healed with conservative treatment.
McIntyre et al. [5] have presented data suggesting that (1) a postoper-
ative fistula is more likely to close than a spontaneously occurring one (26
vs. 17%), (2) a simple fistula is more likely to close than a complex one
(37 vs. 15%), and (3) surprisingly, a high-volume fistula is just as likely to
Figure 9 Epithelialization of the tract, which may prohibit spontaneous closure.
Mangagement of Intestinal Fistulas 333
close as a low-volume fistula (25 vs. 28%). Poor nutritional status and a
transferrin level <200 mg/dL are some of the other factors predicting that
the fistula will be unlikely to close spontaneously [28,29].
MANAGEMENT
The management of patients with intestinal fistulas can be very challenging
and requires a team approach. Treatment can be divided into four phases:
stabilization, investigation, conservative treatment, and decision/definitive
surgery.
Phase 1: Stabilization
At the time of fistula presentation, patients are often in the postoperative
period and have been without adequate nutrition for several days. Prior to
the discharge of intestinal contents from either a drain site or a surgical
wound, clinical progress usually has been poor. The combination of third-
space losses from inflammation and fistula discharge rapidly depletes the
patient’s intravascular volume. The first priority in this situation is the im-
mediate restoration of intravascular volume with crystalloid, colloid, and
blood (when appropriate) to establish tissue perfusion and adequate urine
output. The goal of stabilization of gastrointestinal fistulas is to control the
major complications of fistulas, such as fluid and electrolyte imbalances,
malnutrition, and sepsis, including abscess formation and wound infection.
The patient must be evaluated to determine whether immediate sur-
gery is necessary. Emergency surgery carries a high mortality (55%) [2]
and should be performed for only three reasons: a septic focus requiring
surgical drainage, uncontrolled hemorrhage, or evisceration. If an abscess
has been identified and is approachable through the abdominal wall, percu-
taneous drainage should be considered (Fig. 10). After localization with the
help of computed tomography (CT) scanning or ultrasound, a needle is intro-
duced into the cavity, the contents are aspirated, and a sample is sent for
aerobic and anaerobic culture. Water-soluble contrast can be injected at this
time to delineate the site of origin before draining the abscess [30]. The
latter is accomplished with either a catheter introduced by the Seldinger
technique or through a local procedure. In the septic patient, every effort
should be made to identify and drain all abscesses. Dependent placement
of large-bore catheters is preferred. Uncontrolled sepsis in a patient in
whom an abscess is suspected but cannot be identified may require a formal
laparotomy if the patient’s condition continues to deteriorate. Uncontrolla-
ble sepsis is associated with death in up to 85% of patients, many of whom
have underlying malignancy (50%) or prior radiation therapy (25%) [31].
The importance of surgical intervention to control sepsis has been empha-
334 Wong et al.
Figure 10 An abscess associated with an enterocutaneous fistula (complex type
1) should be drained percutaneously whenever possible.
sized by Reber et al. [7], who found that, in patients who required surgery
to control sepsis, 90% eventually achieved spontaneous closure. When lap-
arotomy is necessary for control of sepsis, no attempt should be made to
definitively repair the fistula; instead, proximal diversion along with drain-
age of the abscess should be performed and definitive repair reserved for a
later time, when the patient has been restored to health (Fig. 11).
Antibiotics should be reserved for patients who are septic. The patient
who is not septic and who has a simple fistula tract (without associated
abscess) does not require antimicrobial therapy. The administration of anti-
biotics in no way obviates the need for adequate surgical drainage. Initial
use should be empirical, covering intestinal organisms such as coliforms,
Bacteroides, and enterococci. Prior to initiation of treatment, fistula drain-
age should be Gram stained and cultured to determine bacterial flora and
sensitivities. The average number of antibiotics used in a series by Soeters
Mangagement of Intestinal Fistulas 335
Figure 11 When percutaneous drainage fails (or is not technically feasible) for
complex type 1 fistulas, a laparotomy with drainage of abscess plus proximal diver-
sion should be performed.
et al. [1] over the course of fistula therapy was six to eight. Thus, indiscrim-
inate use of antibiotics will select out organisms with high levels of antibi-
otic resistance.
Early in this initial management phase, attempts should be made to
diminish intestinal output. This approach not only decreases the fluid and
electrolyte losses experienced by the patient but makes wound and skin
care easier. All patients should have NPO designation, not only to decrease
luminal contents but also to decrease gastrointestinal stimulation and pan-
creaticobiliary secretion. Giving the patient nothing by mouth and placing a
nasogastric tube may remove 4000–7000 mL of secretions from the saliva,
336 Wong et al.
esophagus, stomach, duodenum, pancreas, and biliary tree. In addition, all
patients should be given H
2
antagonists to prevent stress erosions and de-
crease gastric secretions. In 1978, Reber et al. [7] demonstrated a 60%
decrease in fistula output with the addition of intravenous cimetidine. This
method can be extremely helpful in decreasing drainage from high-output
fistulas from the upper gastrointestinal tract.
Several studies have shown that nasogastric tubes do not increase the
closure rate of fistulas [1,9]. The use of such tubes should be restricted to
patients with partial small bowel obstruction. Their long-term use can be
detrimental, causing erosions, bleeding, and late strictures [10]. If a patient
is expected to have prolonged postoperative ileus, consideration should be
given to placing a gastric tube.
Wound and Skin Care
During the stabilization phase of fistula management, early attention must
be directed at wound and skin care. Many of the complications of enteric
contents eroding the abdominal wall can be minimized by early inter-
vention. A skilled and knowledgeable ET nurse working with a dedicated
general nursing team is invaluable. Efforts should be directed toward the
management of abdominal wall fistulas, containment of the effluent, and
maintenance of skin integrity and patient support.
Phase 2: Investigation
Once the patient has been resuscitated and stabilized and the sepsis has
been controlled, the fistula must be investigated to determine (1) the course
and origin of the fistula tract, (2) the presence of a persistent abscess, (3)
the condition of the adjacent bowel, and (4) the presence of distal obstruc-
tion or discontinuity. The best means of evaluating a fistula is a fistulogram,
which is obtained with the use of a soft-tipped catheter (e.g., Foley) or
pediatric feeding tube (if the skin opening is small). Inflating the Foley
balloon prevents leakage of contrast material onto the skin. The fistulogram
may provide information such as (1) the cause of the fistula, (2) the length
of the fistula’s tract, (3) whether the bowel is completely disrupted or the
fistula is a lateral one with the bowel in continuity, (4) whether there is an
abscess cavity, (5) the size of the bowel wall defect, and (6) whether there
is a distal obstruction. A water-soluble contrast material is used, and it
should be injected gently to prevent rupture. Once the origin of the fistula
has been determined, either an upper gastrointestinal and small bowel fol-
low through or a barium enema should be performed to visualize the adja-
cent bowel and rule out distal obstruction. The choice of study depends on
the fistula’s level of origin [32].
The role of CT scanning in the initial evaluation of the fistula’s tract,
once the patient is stable, is limited to the identification of an associated
abscess and, occasionally, to delineate three-dimensional anatomy. CT scan-
Mangagement of Intestinal Fistulas 337
ning may also help to define the extent, nature, and location of underlying
disease [33]. CT is most useful for re-evaluating patients who are not re-
sponding to conservative treatment when an inflammatory process is sus-
pected [32]. Other examinations, such as cystoscopy and intravenous pye-
lography, are used as necessary if other organ systems are involved.
Phase 3: Conservative Treatment
Total Parenteral Nutrition
The development of total parenteral nutrition (TPN) has revolutionized the
treatment of enterocutaneous fistulas [34]. In 1972, Wolfe et al. [35] dem-
onstrated that TPN decreased the output of experimental enterocutaneous
fistulas by 93%. Subsequent clinical studies have confirmed this figure [9].
However, the effect of TPN on the rate of spontaneous closure is less clear.
Most authors claim slightly improved rates of spontaneous closure with
TPN [1,7,9]. This association has led some authors to believe that spontane-
ous closure is primarily a function of fistula etiology, anatomy, and associ-
ated sepsis [4]. Disagreement also exists about the effect of TPN on mortal-
ity. Uncontrolled sepsis is still the most common cause of mortality, and
TPN does not alleviate this problem [1]. The improvement in mortality
rates over the past 20 years may also be attributed to the general improve-
ment in other forms of supportive care. Undoubtedly, the greatest contribu-
tion TPN has made, as stated by Reber et al. [7], is the simplification of
nutritional management for patients with enterocutaneous fistulas. TPN has
allowed better timing for operative intervention when required, improved
the nutritional status of patients undergoing reoperation, and increased the
rate of postoperative recovery.
TPN should be started early, after volume, electrolyte, and clotting
deficits have been corrected and sepsis is under control. It is administered
through a central venous catheter, most commonly placed in the subclavian
vein. Alternatively a percutaneous, intravenous central catheter (PICC) via
the antecubital fossa may be used. The nutritional goal is 30 to 40 kcal/kg/
day with a calorie-nitrogen ratio of 150: 1. Approximately 0.25–0.35 g of
nitrogen per kilogram of body weight per day is necessary to maintain a
positive nitrogen balance. It may be given daily with a concomitant reduc-
tion in glucose solution to patients with diabetes, congestive heart failure,
or chronic obstructive pulmonary disease to decrease the glucose load, the
volume of administration, and carbon dioxide production. In addition, trace
elements, multivitamins, and vitamin K must be given weekly.
Initially, patients must be watched closely for fluid and electrolyte
balance by monitoring daily weights, hydration status, and serum electro-
lyte levels. All electrolytes can be replaced through TPN except for large
amounts of calcium and phosphate, which may be limited by solubility.
The potassium level may fluctuate markedly, and since replacement solu-