Enterocutaneous Fistula

An ECF can occur as a complication following any type of surgery on the GI tract. Indeed, more than 75% of all ECFs arise as a postoperative complication, whereas about 15-25% result from abdominal trauma or occur spontaneously in relation to cancer, irradiation, inflammatory bowel disease (IBD), or ischemic or infective conditions. The etiology of ECFs can thus be characterized as postoperative, traumatic, or spontaneous.

Postoperative

Postoperative causes of ECFs include the following:

• Disruption of anastomosis
• Inadvertent enterotomy - Occurs especially in patients with adhesions, when dissection can cause multiple serosal tears and an occasional full-thickness tear
• Inadvertent small-bowel injury - Occurs during abdominal closure, especially after ventral hernia repair

Disruption of anastomosis can result from inadequate blood flow due to an improper vascular supply, especially when extensive mesenteric vessels have to be ligated. Tension on anastomotic lines following colonic resection, restoration of continuity without adequate mobilization, or a minimal leak or infection can lead to perianastomotic abscess formation, resulting in disruption, as seen in patients with anterior resection for rectal carcinoma. In addition, if anastomosis is performed in an unhealthy (eg, diseased or ischemic) bowel, it can lead to disruption and cause an ECF.

Inadvertent picking up of the bowel during abdominal closure can result in a small-bowel fistula; this especially can occur with the use of open inlay mesh or intraperitoneal onlay mesh repair by the laparoscopic method, when the viscera comes in contact with the mesh, leading to adhesions and sometimes to disruption.

Gastroduodenal fistulas are seen most often after surgery for perforated peptic ulcer, especially in developing countries, where perforated peptic ulcer is more common. In patients with a perforated duodenal ulcer, when the perforation is large, extensive contamination is present. When the duration between perforation and surgery is long, there is a high possibility of a postoperative leak, leading to a lateral duodenal fistula. This problem is difficult to treat, and mortality is high. Other causes of gastroduodenal leakage include surgery for stomach and the biliary tract cancers.

A colocutaneous fistula can develop after colonic surgery, especially when the blood supply to a low colorectal/anal anastomosis is compromised or when there is tension at the anastomotic suture line. This type of fistula can also result from diseases of the colon, such as IBD or malignancy leading to perforation, pericolic abscess formation, and ECF.

Surgery for appendicitis, appendicular perforation at the base, or drainage of an appendicular abscess can also lead to a colocutaneous fistula. Radiation therapy is also another major cause of colonic fistula.[3]  In rare cases, migration of a polypropylene or composite mesh from a hernia repair can lead to ECF formation.[4, 5]

Hew et al reported a rare case of ECF following migration of a hepatic artery infusion catheter in a patient with colorectal liver metastasis.[6]

Traumatic

Traumatic ECF results from iatrogenic surgical trauma to the bowel that may or may not be recognized. Road traffic accidents with injury to the gut can also lead to an ECF.[7]

Spontaneous

Spontaneous causes of ECF, seen in about 15-25% of cases, include the following:

• Malignancy
• Radiation enteritis with perforation
• Intra-abdominal sepsis
• IBD (eg, Crohn disease ^[3] )

Ulcerative colitis (UC) can also lead to spontaneous ECF, but most cases of ECF associated with this IBD occur as a postoperative complication of restorative proctocolectomy.[8] Rarely, inadvertent incision of a malignant tumor can lead to an ECF (see the image below). In this patient, a urachal tumor was inadvertently incised when the patient underwent an appendectomy by midline incision. The patient presented with ECF (colocutaneous fistula) as the urachal tumor that ulcerated on the abdominal wall postoperatively had also infiltrated the sigmoid colon.

A duodenal fistula can occur in association with a perforated duodenal ulcer, but again, it most often arises postoperatively, resulting from a leak.

ECF is a common condition in most general surgical wards. Mortality has fallen significantly since the late 1980s, from as high as 40-65% to as low as 5-20%, largely as a result of advances in intensive care, nutritional support, antimicrobial therapy, wound care, and operative techniques.[9, 10] Even so, the mortality is still high, in the range of 30-35%, in patients with high-output ECFs.

Once a patient develops an ECF, the morbidity associated with the surgical procedure or the primary disease increases, affecting the patient's quality of life, lengthening the hospital stay, and raising the overall treatment cost. Malnutrition, sepsis, and fluid electrolyte imbalance are the primary causes of mortality in patients with an ECF.

Another factor that may be a predictor for poor healing outcomes is psoas muscle density, which can reflect sarcopenia.[11]  Assessment of psoas muscle density can identify patients with ECF who will have poorer outcomes, and these patients may benefit from additional interventions and recovery time before operative repair.

If sepsis is not controlled, progressive deterioration occurs, and patients succumb to septicemia. Other sepsis-related complications include intra-abdominal abscess, soft-tissue infection, and generalized peritonitis.[12]

However, patients with an ECF with favorable factors for spontaneous closure have a good prognosis and a lower mortality.

Favorable factors for spontaneous closure

Spontaneous closure of an ECF is determined by certain anatomic factors. Fistulas that have a good chance of healing include the following:

• End fistulas (eg, those arising from leakage through a duodenal stump after Pólya gastrectomy)
• Jejunal fistulas
• Colonic fistulas
• Continuity-maintained fistulas - These allow the patient to pass stool
• Small-defect fistulas
• Long-tract fistulas

In addition, a fistulous tract of more than 2 cm has a higher possibility of spontaneous closure. Spontaneous closure is also possible if the bowel-wall disruption is partial and other factors are favorable. If the disruption is complete, surgical intervention is necessary to restore intestinal continuity.

Unfavorable factors for spontaneous closure

When an ECF is associated with adverse factors, then spontaneous closure does not commonly occur, and surgical intervention, despite its associated risks, is frequently required. In these patients, the outcome is less likely to be good.[13]

Factors preventing the spontaneous closure of an ECF can be remembered by using the acronym FRIEND, which represents the following[14] :

• Foreign body
• Radiation
• Inflammation/infection/IBD
• Epithelialization of the fistula tract
• Neoplasm
• Distal obstruction - A distal obstruction prevents the spontaneous closure of an ECF, even in the presence of other favorable factors; if present, surgical intervention is needed to relieve the obstruction

In addition, lateral duodenal, ligament of Treitz, and ileal fistulas have less tendency to spontaneously close.[12]

Excoriation

Skin excoriation (see the image below) is one of the complications that can lead to significant morbidity in patients with ECF. When the enteric contents are more fluid than solid, this becomes a difficult problem; the skin excoriation makes it difficult to put a collecting bag or dressings over the fistula, and more leakage leads to an increase in the excoriation.

Features suggestive of an enterocutaneous fistula (ECF) include postoperative abdominal pain, tenderness, distention, enteric contents from the drain site, and the main abdominal wound. Tachycardia and pyrexia may also be present, as may signs of localized or diffuse peritonitis, including guarding, rigidity, and rebound tenderness.

The type of ECF, as based on the output of the enteric contents, also determines the patient's health status and how the patient may respond to therapy. ECFs are usually classified into three categories, as follows[3] :

• Low-output fistula (< 200 mL/day),
• Moderate-output fistula (200-500 mL/day)
• High-output fistula (>500 mL/day)

Patients with ECF present with associated complications, such as sepsis, fluid and electrolyte abnormalities, and malnutrition.

The degree of sepsis depends on the state of the ECF. If the fistula forms a direct tract through which the bowel contents are draining onto the skin, then the sepsis may be minimal, whereas if the fistula forms an indirect tract through which the bowel contents are draining into an abscess cavity and then onto the skin, the degree of sepsis may be higher. In the presence of extensive peritoneal contamination or generalized peritonitis with ECF, the patient can be toxic as a consequence of severe sepsis.

Leakage of protein-rich enteric contents, intra-abdominal sepsis, or electrolyte imbalance–related paralytic ileus, as well as a general feeling of ill health, leads to reduced nutritional intake by these patients, resulting in malnutrition. Nearly 70% of patients with ECFs may have malnutrition, and it is a significant prognostic factor for spontaneous fistula closure.[15]

Sepsis, malnutrition, and electrolyte imbalance are the predominant factors that lead to death in patients with ECF.[16] Rarely, intestinal failure can occur as one of the complications of ECF, which results in significant morbidity and mortality.[17]

A high-output fistula increases the possibility of fluid and electrolyte imbalance and malnutrition.

The following laboratory studies are performed in the evaluation of an enterocutaneous fistula (ECF):

• Total white blood cell (WBC) count - This is important because sepsis can lead to leukocytosis
• Serum sodium, potassium, and chloride levels - Electrolyte abnormalities can result from fluid and electrolyte loss
• Complete blood count (CBC), total proteins, serum albumin, and globulin - These can demonstrate the presence of malnutrition-associated anemia/hypoalbuminemia
• Serum transferrin - Low levels (< 200 mg/dL) are a predictor of poor healing
• Serum C-reactive protein (CRP) - Levels may be elevated

Fistulography

During fistulography (see the images below), a water-soluble contrast agent is injected into the fistulous tract.

Fistulography is conventionally performed 7-10 days after the presentation of an ECF and provides the following information:

• Length of the tract
• Extent of the bowel-wall disruption
• Location of the fistula
• Presence of a distal obstruction

Water-soluble contrast enema

The different types of tracts that can be seen by using a water-soluble contrast enema (WCE) in patients with ECF with failure of low colorectal anastomosis may be classified as follows[18] :

• I – Simple, short blind ending, < 2 cm
• II - Continuous linear, long single, >2 cm
• III - Continuous complex, multiple linear

Tract positions are as follows:

• Anterior - Ventral (10-o’clock to 2-o’clock position)
• Posterior - Dorsal (4-o’clock to 8-o’clock position)
• Lateral - Right (2-o’clock to 4-o’clock position) or left (8-o’clock to 10-o’clock position)

Additional tract features seen with a WCE include a cavity (pooling of contrast within space), a stricture (narrowing of anastomosis, with hold of contrast), or both. The presence of a stricture and a large cavity on WCE predicts failure of healing.

Computed tomography

Computed tomography (CT) is useful for demonstrating intra-abdominal abscess cavities. Such cavities can develop if an ECF has an indirect tract when it first drains into an abscess cavity and then drains to the exterior cavity. If an ECF is associated with intra-abdominal sepsis, then interloop abscesses may be present.

Ultrasonography

A comprehensive ultrasound examination has been employed for the evaluation of postoperative complications after hernia repair.  Whereas point-of-care ultrasound (POCUS) has been commonly used for abscess evaluation, it can also be an alternative in an emergency presentation of an ECF.[19]

Oral administration of a nonabsorbable marker (eg, charcoal or Congo red) can help confirm the presence of an ECF.

Methylene blue diluted in saline can be administered through a nasogastric tube as a simple bedside test to confirm the presence of an ECF, especially in patients with a gastrocutaneous or lateral duodenal fistula. This test can also help to determine whether the leak is from a segment that is in the continuity of the gastrointestinal tract, especially in the case of proximal fistulas. However, because methylene blue loses diagnostic efficacy as it becomes diluted with intestinal secretions, its role in identifying distal ECFs is limited.

The conventional therapy for an enterocutaneous fistula (ECF) in the initial phase is always conservative. Immediate surgical therapy on presentation is contraindicated, because the majority of ECFs spontaneously close as a result of conservative therapy. Surgical intervention in the presence of sepsis and poor general condition would be hazardous for the patient.

However, patients who have an ECF with adverse factors, such as a lateral duodenal fistula, an ileal fistula, a high-output fistula, or a fistula associated with a diseased bowel, may require early surgical intervention.

Zhou et al described a novel technique of using the orchid Bletilla striata in the closure of ECF.[20] In a case of ECF following colonic neoplasm resection managed conservatively, application of B striata led to spontaneous closure of the fistula. This plant was found to suppress inflammation and promote wound healing.

Conservative treatment should usually be administered for a period ranging from a few weeks to a few months. The principles of nonsurgical therapy for ECFs include the following:

• Rehydration
• Administration of antibiotics
• Correction of anemia
• Electrolyte repletion
• Drainage of obvious abscess
• Nutritional support
• Control of fistula drainage
• Skin protection

With the above-mentioned supportive therapy, spontaneous closure occurs in almost 70% of patients. In a study of 186 patients, Reber et al found that 91% of small-bowel fistulas that closed spontaneously did so within 1 month after sepsis was cured. The remaining fistulas that closed spontaneously did so by the end of 3 months after sepsis cure, with the rest of the lesions requiring surgical closure.[21]

Uba et al reported that the majority of ECFs in children closed spontaneously following high-protein and high-carbohydrate nutrition.[22] They found that hypoalbuminemia and jejunal location were important variables resulting in nonspontaneous closure, whereas hypokalemia, sepsis, and hypoproteinemia/hypoalbuminemia were risk factors for high mortality in children with ECF.

Rehydration, electrolyte repletion, and nutritional support

Common fluid and electrolyte problems that must be corrected in patients with an ECF include the following:

• Dehydration
• Hyponatremia
• Hypokalemia
• Metabolic acidosis

The author uses parenteral nutrition more often in patients with a proximal small-bowel ECF, especially if it is in the proximal jejunum, or with a high-output fistula. In patients with a distal ECF, the author prefers to use enteral nutrition whenever possible.

Studies have shown that the provision of only 20% of calories fed enterally may protect the integrity of the mucosal barrier, as well as the immunologic and hormonal function of the gut.[12] Hence, a combination of parenteral and enteral nutrition can be used. In high-output fistulas, the author uses this combination therapy.

In patients with a proximal fistula, if a nasojejunal tube can be introduced beyond the site of the fistula, then these patients can be supported with enteral nutrition, provided that there is at least 4-5 ft (1.2-1.5 m) of small bowel distal to it and no distal obstruction. Patients with chronic small-bowel ECFs may need additional supplementation with copper, folic acid, and vitamin B12.[12]

Total parenteral nutrition

Total parenteral nutrition (TPN) is usually indicated with suspected gastric, duodenal, or small-bowel fistula. When the fistula output is very high, discontinuance of oral intake is recommended because oral intake stimulates further losses of fluids, electrolytes, and protein via the fistula. A decrease in fistula output frequently occurs with the initiation of TPN.

Home parenteral nutrition (HPN) is a vital therapy for patients who have the diagnosis of ECF, and it has reported to be successful for patients with ECF as compared with other HPN patients.[23] Greater provision of protein, more frequent NPO (nil per os) status, and a goal of future surgery should be the focus in ECF patients on HPN.

Water requirements for TPN are 1 mL/kcal/day. Electrolyte requirements for TPN are as follows:

• Sodium (Na) - 80-100 mEq/day
• Potassium (K) - 75-100 mEq/day
• Magnesium (Mg) - 15-20 mEq/day
• Calcium (Ca) - 15-20 mEq/day

Calorie and protein requirements are as follows:

• Maintenance – 25-30 kcal, 1.0-1.2 g/kg/day
• Moderate stress – 30-40 kcal, 1.3-1.4 g/kg/day
• Severe stress – 40-45 kcal, 1.5-2.0 g/kg/day

Protein (g)/6.25 should equal nitrogen (g), and the nonprotein calorie-to-nitrogen ratio should be as follows:

• Maintenance - 200-300:1
• Moderate stress - 150:1
• Severe stress - < 100:1

A standard, general-purpose formula for TPN consists of the following:

• Glucose, 75 g
• Amino acids, 20 g
• Lipids, 30 g/L

The introduction of ethyl vinyl acetate bags has made the admixture of fat emulsion with dextrose and amino acids possible (three-in-one concept).[24] This leads to a more uniform administration of a balanced solution containing the three macronutrients plus micronutrients over a 24-hour period.

Enteral nutrition

Enteral nutrition is the mainstay of treatment for patients with ECFs. In fistulas of the distal ileum, colon, or duodenum, enteral nutrition should be considered and can be administered via various routes. Conventionally, when a gastroduodenal anastomosis or closure is needed in adverse conditions, a concomitant feeding jejunostomy is performed, so that access is available for enteral nutritional support in case of an anastomotic leak.

The other routes of administration can be via nasogastric/jejunal tubes or a gastrostomy. High rates of feeding should be avoided to prevent hyperosmolar diarrhea. Elemental diets, that is, nonresidue balanced diets with protein components reduced to their basic elements, are preferred. When a tube enterostomy is performed, proper fixation is necessary to prevent complications, such as dislodgment of the tube or antegrade migration in the gastrointestinal (GI) tract.[25]

Martinez et al reported a prospective randomized trial on the effect of preoperative administration of oral arginine and glutamine in 40 patients with ECF undergoing definitive surgery, of whom 20 received standard medical care (control group) and 20 received enteral supplementation with arginine 4.5 g/day and glutamine 10 g/day for 7 days prior to surgery (test group).[26] The primary outcome was recurrence; secondary outcomes were pre- and postoperative serum interleukin (IL)-6 and C-reactive protein (CRP) levels and infectious complications. The recurrence rate was 10% in the test group and 45% in the control group. The test group had lower IL-6 and CRP levels and no infectious complications. 

Fistuloclysis

Enteral nutrition can also be administered in patients with high-output proximal jejunocutaneous or ileocutaneous fistulas with good mucocutaneous continuity. Feeding can be administered through a feeding tube inserted in the distal limb of the ECF. Teubner et al and Ham et al reported good results with this method in select patients to improve the nutrition of the patient, which is helpful for subsequent fistula closure and promotes healing of the fistula.[27, 28, 29]  An interprofessional approach is needed.[30]

Skin management

Irrgang et al developed a fistula assessment guide that has aided skin management related to ECFs.[31]  This guide is based on the following characteristics:

• Origin of fistula
• Nature of effluent
• Condition of skin
• Location of fistula opening

For a high-output fistula, a pouch system is preferable to a conventional skin dressing. For a low-output fistula, a skin barrier with a dressing or pouch is advocated.

The degree of skin irritation present (from erythema to maceration to skin loss) guides the type of skin-protecting agents that should be applied and the type of pouch system that should be used. In addition, an important consideration is whether the opening is flush with the skin, retracted and deep, close to bony prominences, or in an open wound.

Pouches used for skin care

When the fistula output is high, it is desirable to use a pouch for collecting the enteric effluents. Ostomy pouches in one- or two-piece designs with either a drainable clip or a urostomy-type closure can be cut and fit to perifistular skin. If the area of the fistula is on an irregular body contour (eg, close to bony prominences), then a one-piece pouch is more suitable because it can adhere better.

A transparent pouch is preferred to an opaque pouch, for visualization of the fistula. A pouch with a skin-barrier backing is more durable than one with an adhesive backing. Wound manager bags (see the image below) are preferable in that they are specifically designed to help make wound care easier with good skin protection and access to the wound for its care.

Skin barriers

Powder, paste, wafers, spray, and creams are used as skin barriers for the protection of skin from the enteric effluents.

Pectin-based wafers that melt and seal with the skin provide a good barrier and offer protection for a variable period before the skin breaks down and ulcerates. In low-output fistulas, absorbent dressings can be put on top of the skin-barrier wafer to absorb any effluent overflow. The skin wafer protects the adjoining skin from erythema and maceration.

Pectin- or karaya-based powders and paste are used. Powders are preferred over a paste in wet, weepy, perifistular skin when severe skin maceration is present. A generous amount of powder should be used and continuously added for good results. In patients with weepy skin and a high-output fistula, management becomes difficult.

A spray provides a protective film and is helpful for pouching, but it might not be beneficial if used alone.

Zinc creams (see the images below) are used to waterproof and protect the skin. Again, a generous amount with continuous replacement is necessary because the cream is washed away with discharging enteric effluents.

Control of fistula drainage

The fistula tract is intubated with a drain (see the image below). Volume depletion from a proximal high-output fistula can be controlled with the use of the long-acting somatostatin analogue octreotide, which acts by inhibiting GI hormones. The administration of octreotide reportedly diminishes fistula output, but whether it shortens the time required for fistula closure remains to be determined.[32]

Draus et al recommended a 3-day trial of octreotide, maintaining that if the fistula output is reduced during this time, then administration of the drug should be continued.[33] (Octreotide use is associated with an increased incidence of cholelithiasis.[12] ) Two meta-analyses showed that somatostatin and its analogues decreased the time for fistula closure and increased the closure rate.[34, 35] However, there was no significant change in the mortality with the use of somatostatin or its analogues.

A study on management of high-output ECF with continuous triple-cavity tube drainage in combination with sequential somatostatin-somatotropin administration was reported in three patients with three different forms of ECF (duodenal, jejunal and ileal) and three different approaches to drainage tube (through the initial drainage channel, puncture with dilatation, and tract reconstruction, respectively).[36] This measure was carried out with the aims of creating a stable controlled fistulous tract and promoting its healing. It was found to be safe and effective, especially when surgery was contraindicated.

Hyon et al reported on a vacuum-sealing method to reduce output, in which a semipermeable barrier was created over the fistula by vacuum packing a synthetic, hydrophobic polymer covered with a self-adherent surgical sheet. To set up the system, the investigators built a vacuum chamber equipped with precision instruments; the chamber supplied subatmospheric pressures of 350-450 mm Hg. The pressure reduced the daily fistula output from 800 mL to about 10 mL, thus restoring bowel transit and physiology.[37]

Draus et al reported that the use of a vacuum-assisted closure (VAC) system for wounds, which consisted of an evacuation tube embedded in a polyurethane foam dressing, helped improve the condition of the wound, prevented skin excoriation, and promoted wound contracture and healing.[33]  Administration of agents that decrease intestinal pressure may enhance the efficacy of VAC.[38]

Oliva et al described a nonoperative technique involving the insertion of an occlusive device to redirect the intestinal content to the distal bowel in patients with lateral high-output ECF.[39] This was a transient procedure aimed at reducing the fistula output.

Electrical nerve stimulation

Electrical nerve stimulation (ENS) increases blood flow in ischemic tissues and encourages healing. Berna et al reported the successful use of ENS in two patients with a low-output ECF. In the study, the direction and depth of the fistula tract were ultrasonographically determined. A sterile compress impregnated with saline solution was then introduced through the fistula. The positive electrode was positioned on the compress, and the negative electrode was positioned over the fistula orifice.[40]

The treatment was given once daily for 1 hour, with one patient requiring 10 treatment sessions to heal and the second patient requiring 20 sessions. ENS was well tolerated by both patients, and no complications were noted. No recurrence of the fistula developed over a 3-year follow-up period.

Laser ablation for chronic ECF after failed conservative therapy

Laser ablation has been used for the treatment of chronic ECFs after failure of conservative therapy. In a study by Srinivasa et al, three patients underwent laser ablation for treatment of eight ECFs (mean duration of ECF, 28 months; mean fistula output, 134 mL/day).[41] Initially, all of the ECFs responsed completely to laser ablation, with no major or minor complications; however, later three ECFs subsequently required repeat treatment. Overall, at a mean follow-up of 53 days, seven fistulas healed, and one showed a markedly reduced output (10 mL/day).

Andrés Moreno​ et al reported the successful use of combination therapy with a laser diode followed by embolization of the tract with platinum coils and cyanoacrylate to close an ECF after multiple surgical procedures.[42]

Indications for surgery

Patients who an ECF with adverse factors may require earlier surgical intervention. These adverse factors include the following:

• Lateral duodenal or ligament of Treitz fistula
• Ileal fistula
• High-output fistula
• Fistula associated with diseased bowel, distal obstruction, or eversion of mucosa (see the image below)

Enteroatmospheric fistula (EAF), a special subset of ECF, is defined as a communication between the GI tract and the atmosphere.[43] It can occur as a complication of "damage control" laparotomy (DCL) and results in significant morbidity and mortality. The etiology is complex and ranges from persistent abdominal infection, anastomotic dehiscence, and adhesions of the bowel to fascia with a laparostoma. Multiple fistulas and preoperative CRP levels higher than 0.5 mg/dL have been reported to be associated with recurrence after closure of EAF.[44]

Because EAFs almost never close spontaneously, definitive repair usually requires major surgical intervention. Complex abdominal-wall reconstruction immediately after fistula resection is necessary for all EAFs once the infection has subsided, which may be 6-12 months after the original insult.[45] A “fistula patch” technique has also been reported for protecting open abdominal wounds from being contaminated by intestinal fistulae drainage, while and simultaneously applying enteral nutrition.[46]

Because the possibility of spontaneous closure is reduced in patients with adverse factors, surgical intervention should be undertaken after a 4- to 6-week trial of conservative therapy, if no signs of spontaneous closure exist. Surgical procedures in patients with adverse factors can include draining an abscess, creating stomas by exteriorizing the bowel, or creating controlled fistulas. When feasible, resection of the fistula with restoration of GI continuity is performed.

In patients with no associated adverse factors, the author usually waits for about 3-4 months before planning surgical therapy for an ECF.

Surgical therapy[47]  should be undertaken in patients with conventional fistulas without any adverse factors if the patient is stable, has no sources of sepsis, and can withstand the resectional procedure needed for fistula closure.[12] It is also important that it be technically feasible to perform the procedure without posing a very high risk of injury to the bowel or other important structures. Patients with an almost completely healed wound with a fistulous opening (shown below) have a good chance of responding to surgical therapy.

Operative details

In addition to ensuring that patients are stable and free from sources of sepsis before surgical correction of an ECF is undertaken, antibiotic prophylaxis should be performed and parenteral nutritional supplementation provided as necessary during the preoperative and the perioperative periods to achieve good results. Enteral feeding should be decreased to allow luminal antibiotic preparation. Antibiotic therapy should be administered after the culture sensitivity of earlier-grown organisms has been checked.[12]

Incision

When performing surgery for an ECF, the author makes a point of always entering the abdomen through a fresh incision, given the possibility that the gut may be adherent to the site of the incision of the index operation. If the native incision follows a supraumbilical midline route, then the author takes an infraumbilical midline route and then extends it to the operative site.

If it is in the middle portion of the midline, then the author makes either an incision in the midline superior or inferior to the native incision or a transverse incision to approach the abdomen. The author always enters the peritoneal cavity in a relatively virgin area to lessen the chance of an inadvertent enterotomy.

Excision and restoration of bowel continuity

Once an assessment is made in the peritoneal cavity, then the entire bowel from the ligament of Treitz to the rectum is made free of all adhesions. Once this is achieved, the fistulous site is dissected free from the surrounding structures, and a complete excision is done. The author prefers to restore bowel continuity by using a two-layer anastomosis, employing interrupted nonabsorbable suture of healthy and well-vascularized bowel. The author uses this approach for small-bowel as well as large-bowel anastomosis.

An inner layer consisting of continuous absorbable suture and an outer layer consisting of interrupted nonabsorbable sutures can also be used to restore bowel continuity. Other alternatives include the use of staplers, especially in low colorectal anastomoses.

Treatment of abscess or diseased bowel

If an abscess or diseased bowel segments are seen, then drainage of the abscess or resection of the diseased bowel is performed.[10] If the patient is too sick to tolerate a resectional procedure, then exteriorization of the bowel via ileostomy or colostomy is carried out.

Roux-en-Y drainages or a serosal patch can sometimes be used, especially for a lateral duodenal fistula following a leak after simple closure of a perforated duodenal ulcer.[12] However, the results of these procedures are not very encouraging. Converting a lateral duodenal fistula into an end fistula with a tube duodenostomy is a good option but may not be possible in most patients.

If anastomosis is performed close to a duodenojejunal flexure, then adequate decompression by gastrostomy and feeding jejunostomy are carried out. The latter is also performed when proximal fistula repair is undertaken (eg, lateral duodenal fistula).

Myocutaneous or fasciocutaneous flap

De Weerd et al described the use of a sandwich-design myocutaneous flap cover to close a high-output ECF.[48] In the initial phase of treatment, the authors used a VAC system for wound care to promote the development of granulation tissue around the fistulous opening. The fistula was then closed with serratus muscle from a composite free latissimus dorsi–serratus flap. The large abdominal wall defect was closed with the musculocutaneous latissimus dorsi flap taken from the composite flap. The placement of a VAC system between the serratus and the latissimus dorsi helped to fix the serratus to the fistula.

Successful direct repair of an ECF using a surrounding fasciocutaneous flap has also been reported.[49]

In the postoperative phase of surgical therapy for an ECF, good nutritional status is essential because healing of the tissue and anastomosis depends on it.

Antibiotic coverage is needed if the operation is performed in the presence of sepsis. Any flare-up of sepsis increases the possibility of breakdown of the anastomosis and of the abdominal wall closure (leading to dehiscence). However, unnecessary use of antibiotics can lead to resistance and should therefore be avoided.

Fluid and electrolyte balance with appropriate correction is also important, especially in patients with adverse factors (eg, high-output fistula).

Patients who develop spontaneous fistula due to disease need appropriate therapy (eg, infliximab for Crohn disease or antituberculous therapy for tuberculosis) during follow-up to prevent disease recurrence or recurrence of the ECF.[50]  In patients with a malignancy-related ECF, appropriate chemotherapy and radiation, if required, are administered to control the primary disease.

After healing of a conventional fistula by spontaneous closure, patients should be informed that because healing occurs with secondary intention, there is a possibility of development of an incisional hernia as a long-term complication of ECF.

Use of fibrin glue and plugs

In a study of 10 patients with low-output (n = 7) or high-output (n = 3) ECFs that had failed to close after conservative therapy, Rabago et al observed that fibrin glue completely sealed the majority of ECFs.[51] Once a fistula had been endoscopically located, 2-4 mL of reconstituted fibrin glue (Tissucol 2.0 at 37°C) was injected through a catheter. The patients required a mean of 2.5 treatment sessions (range, 1-5), and the mean healing time was 16 days (range, 5-40). After treatment, 87.5% of the low-output fistulas and 55% of the high-output fistulas sealed completely. No complications occurred.

Issak et al reported a case in which concurrent over-the-scope-closure (OTSC) stent placement was successfully used in a patient who had a perforated duodenal ulcer with chronic recurrent ECF.[52] Under fluoroscopic guidance, a fully covered metal stent was placed into the duodenum.

Truong et al described the use of a polyglactin plug in combination with fibrin glue in the treatment of ECFs.[53] After the site of an ECF or anastomotic leak was endoscopically sealed with the plug and glue, seven of the study's nine patients healed completely.

In another study, however, when fibrin glue was introduced directly into an ECF through the fistula opening in the skin, the results were not encouraging, with the fistula healing in only one out of eight patients.[33]

Autologous platelet-rich fibrin glue also has been reported to be safe and effective in the treatment of low-output ECFs by reducing the closure time and promoting closure.[54]

Good results with endoscopic therapy suggest that this technique, when possible, can be used when other conservative methods fail. 

Successful closure of a duodenocutaneous fistula has been reported with the use of the Biodesign enterocutaneous fistula plug (Cook Medical, Bloomington, IN), which is derived from a biologic plug used in fistula-in-ano tracts. The plug is introduced into the fistulous tract percutaneously.[55]

Extracellular matrix enterocutaneous fistula plugs (ECMFPs) are an alternative in patients with low-flow ECFs, especially when they are not candidates for a surgical procedure. In a study assessing the use of ECMFPs in 18 patients with enteric fistulas, Smith et al reported that fistula closure was achieved in 25% of gastrocutaneous fistulas, 44% of enterocutaneous fistulas, and 50% of colocutaneous fistulas.[56] The median time of fistula closure was 25-29 days. Recurrence after closure and failure of closure were more common in patients with high-flow fistulas.

Gelfoam embolization

Lisle et al described successful treatment of three cases of ECF with embolization of Gelfoam at the enteric opening of the fistula.[57] In this technique, the ECF was assessed by means of computed tomography (CT) and fistulography to rule out any intra-abdominal abscess, distal bowel obstruction, active bowel inflammation, or foreign body that would prevent the fistula from healing. Fistulography also provided information about the fistulous tract and the site of communication with the bowel.

A 5-French introducer sheath was passed along a guide wire into the tract under fluoroscopy and then removed, after which Gelfoam strips or pledgets soaked in contrast material were introduced into the tract through the sheath and pushed down to plug the enteric opening of the ECF. All of the patients healed completely, with no recurrence of ECF over a 2- to 3-year follow-up period.[57]