Enterocutaneous and enteroatmospheric fistulas

INTRODUCTION — 

A fistula is an abnormal connection between two body parts or organs. Enteric fistulas originate from a portion of the gastrointestinal tract; the loss of bowel wall integrity permits the drainage of enteric contents into an adjacent organ or open surface [1].

This topic reviews two types of similar enteric fistulas: enterocutaneous fistulas (ECFs) and enteroatmospheric fistulas (EAFs) [2].

●Enterocutaneous fistula – An ECF involves an abnormal connection between the gastrointestinal tract and the skin, which drains enteric contents through an opening in the skin (picture 1).

●Enteroatmospheric fistula – An EAF is an abnormal connection of the gastrointestinal tract to an open wound without surrounding skin or overlying tissue (ie, an open abdomen), which allows the enteric contents to drain directly from the opening in the bowel (picture 2) [3].

Fistulas that occur in other areas of the body are discussed in other topics, including:

●Colovesical fistulas (see "Colovesical fistulas")

●Diverticular fistulas (see "Diverticular fistulas")

●Urogenital fistulas (see "Urogenital tract fistulas in females")

●Anorectal fistulas (see "Anorectal fistula: Clinical manifestations and diagnosis" and "Rectovaginal and anovaginal fistulas")

●Tracheal or bronchoesophageal fistulas (see "Tracheo- and broncho-esophageal fistulas in adults")

●Bronchopleural fistulas (see "Bronchopleural fistula in adults")

ETIOLOGY AND PATHOGENESIS — 

The majority of ECFs and EAFs are iatrogenic from abdominal or intestinal surgery [4-6]. In a 2022 systematic review and meta-analysis of 53 studies (n = 3078), 89.4 percent of ECFs developed in patients after surgery (table 1) [7]. Common etiologies were inflammatory bowel disease, trauma, malignancy, and radiation. Less common ECF etiologies were ischemia, tuberculosis, and complicated diverticular disease. The most common ECF anatomic site was the small bowel (70 percent), followed by the colon (16.7 percent) and gastric/duodenal (8 percent), and unknown [7].

Iatrogenic — Postoperative fistulas can develop after anastomotic leaks or after a missed enterotomy. Less often, fistulas can develop after the erosion of mesh or graft material used in hernia repairs or vascular surgeries into nearby bowel.

Patients who are malnourished, immunosuppressed, or have Crohn disease are more likely to develop a postoperative fistula. Additionally, patients who undergo emergency laparotomy procedures, have a traumatic injury, or have an abdominal infection have an increased likelihood of ECF/EAF development.

Open abdomen — In trauma and emergency abdominal surgery patients, open abdomen is a significant risk factor for ECF/EAF. An important strategy to prevent ECF/EAF in such patients is to achieve definitive fascial closure at the laparotomy site as early as possible (picture 3).

●In a report of 572 patients who required open abdomen after trauma operative procedures, failure to achieve definitive delayed fascial closure was associated with a higher rate of ECF (13 versus 5 percent) [8]. Other independent predictors of ECF/EAF and abdominal sepsis/abscess after trauma included large bowel resection (adjusted odds ratio 3.56), large volume intravenous fluid resuscitation greater than 5 liters, and increased number of re-laparotomies [9].

●The open abdomen approach is also used in non-trauma emergency general surgery patients with secondary peritonitis, and a systematic review of 74 studies (n = 4358) reported ECF/EAF rates of 5.7 percent with negative pressure wound therapy (NPWT) plus fascial traction, 14.6 percent for NPWT only, and 17.2 percent after mesh inlay [10].

For abdominal sepsis and secondary peritonitis, it is not known whether it is better to leave the abdomen open or closed with on-demand re-laparotomy. The VACOR randomized trial is currently enrolling patients (Clinicaltrials.gov NCT03932461) with a primary endpoint of complications including ECF/EAF [11]. The management of the open abdomen is the focus of another topic. (See "Management of the open abdomen in adults".)

Spontaneous — Spontaneous ECFs can be a result of several causes. A helpful pneumonic is "FRIENDS":

●Foreign body within or adjacent to the tract

●Radiation exposure of the site

●Inflammation (Crohn disease) or Infection at the site

●Epithelialization of the fistula tract

●Neoplasm

●Distal intestinal obstruction

●Steroids or other medications that impair wound healing

Crohn disease is the most common cause of spontaneous fistulas [12,13]. It can also cause postoperative fistulas in patients who require surgical treatment. Spontaneous fistulas are less likely to heal without operative intervention. (See "Clinical manifestations, diagnosis, and prognosis of Crohn disease in adults" and "Surgical management of Crohn disease".)

PATIENT PRESENTATION — 

Most patients with an ECF/EAF are in the postoperative period and have not had normal, expected recoveries. Common postoperative complications include surgical site infection, abdominal abscesses, fascial dehiscence, anastomotic leak, and/or the need for an open abdomen approach.

ECF/EAF commonly manifests as enteric or bilious drainage from an incision or open wound site. The effluent from the wound is characterized as bilious if it is a small bowel fistula or frank stool if it is a colonic fistula [14]. These patients may lose a large amount of enteric content leading to electrolyte abnormalities, dehydration, skin irritation, and malnutrition. Abdominal infection and abdominal sepsis symptoms including fever and/or leukocytosis may also be present.

DIAGNOSIS — 

Bilious drainage from an abdominal wound is concerning for a possible ECF/EAF, and drainage of enteric contents from an abdominal wound is diagnostic of an ECF. When in doubt, the drainage can be sent for bilirubin to confirm the presence of enteric contents. The diagnosis of EAF requires visualization of leakage of enteric contents from a bowel segment, which is only possible in an open abdominal wound or open abdomen.

Although the diagnosis of ECF/EAF is clinical, delineation of the fistula anatomy requires imaging studies. (See 'Anatomy definition' below.)

MANAGEMENT — 

The management of ECF/EAF typically occurs in three phases (algorithm 1). The acute phase (zero to seven days) focuses on identifying and treating any associated sepsis. During the chronic phase, the patient's nutrition is optimized, and fistula output is managed to protect the surrounding skin and prevent dehydration. This phase is usually the longest, potentially lasting up to one year. About one-third of patients achieve fistula closure within this phase, often by five to six weeks; beyond this timeframe, surgical intervention is usually required. Surgical closure is generally performed after 6 to 12 months, allowing time for the patient to be in optimal condition and for the skin around the fistula site to become supple.

"SNAP" is a pneumonic for the four steps of ECF/EAF management:

●Sepsis control and Skin care

●Nutritional support

●Anatomy definition (diagnostic evaluation and imaging)

●Patience and planned procedure to close ECF

Sepsis control — The most important determinant of outcomes in patients with ECFs is timely and effective management of abdominal infection and sepsis. Sepsis accounts for 80 percent of ECF deaths, and septic shock is associated with a 40 percent mortality rate.

In septic patients, broad-spectrum, empiric antibiotics that cover all potential enteric pathogens should be started within 60 minutes [15]. The choice of empiric antibiotics is discussed elsewhere. (See "Antimicrobial approach to intra-abdominal infections in adults", section on 'Empiric antimicrobial therapy'.)

Adequate source control of abdominal infection and sepsis should be achieved as quickly as possible [16,17]:

●Abscess drainage – Most commonly, the sepsis originated from an ECF-associated abscess or infected fluid collection in the abdomen, retroperitoneum, and/or pelvis, which can be identified by computed tomography (CT) imaging with enteral and intravenous contrast (See 'Anatomy definition' below.).

Intra-abdominal or retroperitoneal abscesses can be drained percutaneously by interventional radiology (image 1). Large retroperitoneal abscesses refractory to percutaneous drainage may be treated by video-assisted retroperitoneal debridement. Still, some patients may require laparotomy if source control cannot be achieved with less invasive options.

●Re-laparotomy – In patients who develop peritonitis from an acute ECF draining into the peritoneal cavity, or if it has been a short time since the index operation, re-laparotomy to evaluate for possible ECF resection or repair and proximal diversion can be considered. ECF/EAF resection to normal bowels is the best course of action if feasible. In most acute cases with distal small bowel or colonic fistula, repair and proximal diversion is another approach; however, this depends on the anatomic location of the fistula, size of the fistula, etiology, and extent of abdominal infection. (See 'Surgical fistula closure' below.)

Abscess and peritoneal fluid cultures should be sent to microbiology so that antibiotics can be tailored to culture results. Antibiotics can be stopped at four days if complete source control has been achieved [18]. Otherwise, antibiotics should be continued until all clinical and laboratory signs of infection have fully resolved. (See "Antimicrobial approach to intra-abdominal infections in adults", section on 'Duration of therapy'.)

Skin care — It is imperative to establish a wound care and ECF/EAF drainage plan to protect the skin, minimize complications at the surgical incision site if present, and allow for accurate ECF/EAF output measurement. Skin care is best provided jointly by the wound and ostomy care team and the surgical team based on the fistula output and the integrity of the peri-fistula skin condition:

●Most patients with low-output ECF (<200 mL per day) and good skin integrity can be managed with a wound manager or ostomy appliance. Ostomy skin care techniques such as barrier films and stoma powder may be used to keep the peri-fistula skin intact. (See "Ileostomy or colostomy care and complications", section on 'Pouch systems and routine ostomy care'.)

●For patients with a high-output ECF (>500 mL per day), there are significant challenges to skin care.

•Initially, if the skin is excoriated, zinc oxide protective barrier cream is applied to the skin with fluff dressings and abdominal dressing pads changed frequently underneath an abdominal binder or burn net cover to keep the dressings in place and avoid tape to the skin.

•Once the skin is healing or has healed, skin care may transition to negative pressure wound therapy (NPWT) (figure 1) or wound manager/ostomy appliance. In a review of 10 studies (151 patients with postoperative ECF), successful fistula closure was achieved with vacuum-assisted closure in 64.6 percent of patients after a median of 58 (12 to 90) days [19].

●For patients with an EAF, all efforts should be made to convert the EAF to an ECF and slowly promote wound closure.

•If the EAF is small and there is no distal obstruction present, the EAF could close with good wound care including judicious use of NPWT (picture 4) [20].

•For EAFs associated with large open wounds, it is mandatory to continually decrease the size of the sponge for NPWT with every dressing change and to use delayed primary suture closure of the skin, promote closure of the large open wound, and then eventually transition to a wound manager connected to Foley bag to facilitate hospital discharge (picture 5).

•When NPWT is used with EAF and large open wounds, a fistula crown or fistula funnel may be added to assist with the management of high-output EAF and maintenance of NPWT to allow the open wound to close more quickly.

Control of the volume of fistula output is an important aspect of providing optimal skin care and is discussed separately below. (See 'Conservative management' below.)

Nutrition support — Perioperative malnutrition is common in ECF/EAF patients, can be associated with increased risk for anastomotic leak, complications, and mortality, and should be treated with appropriate nutritional support to ensure optimal patient outcomes [21]. (See "Nutrition support in critically ill adult patients: Initial evaluation and prescription".)

Nutritional assessment — The Nutrition Risk in Critically Ill (NUTRIC) score (which is calculated using age, acute physiology and chronic health evaluation [APACHE] II score, sequential organ failure assessment [SOFA] score, comorbidities, and days from hospital to intensive care unit admission) has been validated to identify ECF/EAF patients who are at high nutrition risk [22]. Patients with higher NUTRIC scores have higher mortality, and multiple studies have confirmed that they benefit from increased nutritional support [23-25].

Traditional nutrition assessment tools such as anthropometry are not validated in ECF/EAF patients. Biochemical markers of nutritional status (albumin, prealbumin) do not reliably identify malnutrition since they are also acute phase reactants and may be elevated due to inflammation [26].

Parenteral versus enteral nutrition — Nutrition support can be provided in two forms (table 2):

●Parenteral nutrition (PN) is appropriate nutritional support for high-output ECF/EAF and will usually result in decreased ECF/EAF output. However, PN induces intestinal mucosal atrophy and does not support normal gut immune and hormonal function [27].

●Enteral nutrition is potentially appropriate for low-output ECF/EAF but may increase the volume of the fistula output. Enteral nutrition protects the integrity of the intestinal mucosal barrier and preserves the normal immunologic and hormonal function of the gut (trophic effect) since enterocytes and intestinal immunocytes rely on enteral nutrients [28].

Personalization of nutrition support is important in the care of patients with ECF/EAF:

●Most patients with ECF or EAF (>75 percent) are initially managed with PN. Randomized trials confirm that PN is safe and effective for critically ill patients [29-32].

●For patients who have low-output ECF or EAF, enteral nutrition can be slowly introduced while the volume of fistula output is carefully monitored. In the case of a low-output ECF converting to a high-output ECF with enteral nutrition, PN may need to be reinstituted if the volume of output cannot be reduced with medications. (See 'Conservative management' below.)

●If enteral nutrition is tolerated without a significant increase in fistula output, this is the preferred route. A transnasal feeding tube should be considered if there is poor oral intake or swallowing dysfunction. In some cases (eg, proximal jejunal ECF), the feeding tube can be placed beyond the ECF site.

●In patients with a proximal small bowel fistula, enteral feeding via a tube placed in the distal lumen of the fistula (fistuloclysis or enteroclysis) is an option [33] (picture 6). In these patients, we commonly use elemental enteral feeding formulas to promote prompt absorption in the small bowel. We also use a more concentrated enteral formula (2 kcal/mL) so that goal enteral nutrition feeding rates can be achieved without high volume rates.

●For patients with both proximal and distal small bowel ECFs, collection of bile and enteral contents from the proximal fistula and reinfusion into the distal fistula (enteroclysis) may prevent high-volume enteric losses [34,35]. A new option for the nutritional management of patients with high-output ECF includes chyme reinfusion with a pump inside of the stoma appliance, which is controlled by the patient based on comfort level [36-38]. The REINFUSE trial is ongoing to evaluate the efficacy of this device (NCT04577456) [39].

Monitor for and treat refeeding syndrome — In all patients with malnutrition and/or >20 percent loss of body weight, serum electrolytes (magnesium, phosphate, potassium, calcium) should be monitored and repleted daily when nutritional support is initiated to avoid cardiac dysrhythmias due to refeeding syndrome (table 3) [40]. Refeeding syndrome is discussed in detail elsewhere. (See "Anorexia nervosa in adults and adolescents: The refeeding syndrome".)

The 2020 ASPEN Consensus defines refeeding syndrome as "a decrease in any one, two, or three of serum phosphorus, potassium, and/or magnesium levels by 10 to 20 percent (mild), 20 to 30 percent (moderate), or >30 percent and/or organ dysfunction resulting from a decrease in any of these and/or due to thiamin deficiency (severe) occurring within five days of reintroduction of calories" [41].

When patients manifest hypophosphatemia due to refeeding syndrome, it is important to temporarily decrease all nutrition support (protocolized caloric restriction) and correct all electrolyte and vitamin deficiencies. This has been associated with a survival benefit in randomized trials [42].

Anatomy definition — Diagnostic imaging is required to determine the fistula anatomy; assess for any associated intra-abdominal abscesses or fluid collections; determine if there is associated intestinal ischemia, stricture, or obstruction that will prevent ECF/EAF closure; and assess the overall intestinal reserve of the patient. It is very important to fully define the anatomic location of the ECF/EAF, which will allow for personalized management of nutrition, wound care, and future interventions.

●CT with contrast – Abdominopelvic CT with enteral and intravenous contrast is recommended as the initial diagnostic imaging modality, and a slow (long) enteral contrast prep is required to ensure that the enteral contrast makes it into the colon.

●CT fistulography – If the CT imaging confirms a proximal small bowel fistula, but most enteral contrast drains out the fistula site, then a fistulogram should be added to evaluate the bowel distal to the ECF/EAF to assess for distal strictures or obstruction. If CT imaging does not confirm fistula, a fistulogram is indicated. CT fistulography has replaced fluoroscopic fistulogram since it can provide optimal visualization of the fistula site and cross-sectional imaging of all associated structures in proximity [43].

In patients with ECF/EAF that are "budded" (intestinal mucosa everted as in an ostomy), it is easy to perform a fistulogram by cannulation of the fistula with a small (4 or 5 French) vascular catheter or Foley-type catheter or small gastric/feeding tube and manual injection of enteral contrast using a syringe (image 2).

Patience and planned procedure to close ECF — Once sepsis management, skin care, and nutritional support have been optimized, it is then important to discuss potential options regarding ECF/EAF closure with the patient and family/caregivers.

These options include conservative management hoping for spontaneous closure, non-surgical closure (eg, interventional radiology sealant approaches, endoscopic clips, endoscopic suturing), and surgical closure. Surgical closure is commonly delayed for six months to one year to permit dense intraperitoneal adhesions to "mature," which can make the adhesiolysis easier and decrease rates of inadvertent enterotomy during re-laparotomy.

Whether ECFs/EAFs will close with conservative management depends on patient and fistula characteristics outlined in this table (table 4).

Conservative management — Adequate control of fistula output ensures that patients remain euvolemic, and skin care is optimal such that spontaneous closure can potentially occur. Fistula output can be reduced by the following dietary and pharmacologic methods [44] (table 5). A stepwise escalation of treatment is presented here (algorithm 2).

●Restriction of hypo-osmolar fluids intake – Restricting hypo-osmolar fluids and enteral feeds to 500 to 1000 mL per day is useful. Hypo-osmolar oral fluids can be replaced by oral electrolyte rehydration solutions [45].

●Antimotility agents – Antimotility agents such as loperamide (Imodium) and diphenoxylate-atropine (Lomotil) can decrease output [46]. We start with loperamide 2 to 4 mg four times a day and titrate up to a maximum dose of 8 mg four times a day. If the output remains higher than 500 mL/day, we add codeine starting at 15 mg two times a day and may titrate up to 15 mg four times a day. Because supratherapeutic doses of loperamide can prolong QTc and cause cardiac arrhythmias, it is advisable to obtain an electrocardiogram when increasing the dose to >16 mg/day.

●Antisecretory agents – Anti-secretory agents include proton pump inhibitors (PPIs), H2 receptor antagonists (H2RA), somatostatin, and synthetic somatostatin analogues (eg, octreotide). PPIs and H2RAs work by decreasing gastric and intestinal secretions. Somatostatin and its analogues increase intestinal transit time, decrease endogenous fluid secretions, and increase the absorption of fluids and electrolytes. In multiple meta-analyses, somatostatin analogues reduced the time to (14 versus 21 days) and increased the percentage of (72 versus 44 percent) fistula closure [47,48].

We start patients on high-dose PPI (eg, pantoprazole 80 mg twice a day intravenously [IV] or 40 mg twice a day orally). In case the patient has refractory hypomagnesemia, H2RA should be used instead of PPI (eg, famotidine 20 mg IV or orally twice daily or cimetidine 400 mg orally four times daily). PPI or H2RA can be started at the same time as the antimotility agents (eg, loperamide).

If the fistula output is persistently >500 mL/day despite usual antisecretory and antimotility agents detailed above, we start octreotide at 100 mcg three times daily IV or subcutaneously. If the patient develops nausea, we change to continuous intravenous infusion at 12.5 to 50 mcg/hour, which is associated with less nausea than other forms of dosing. The daily maximum dose is 1200 mcg per day. Octreotide should be stopped after three to five days if there is not a >50 percent reduction in ECF output [49].

●GLP-2 analogue (teduglutide) – GLP-2 is an endogenous trophic hormone secreted by the intestinal L cells that promotes intestinal growth and proliferation through downstream mediators including epidermal growth factor and insulin-like growth factor-1. Exogenous GLP-2 stimulates mesenteric blood flow, intestinal cell proliferation, intestinal villus growth, and improves intestinal nutrient and fluid absorption. A very small pilot randomized trial of adults with low-output ECF reported that two months of teduglutide (GLP-2 analogue with a much longer half-life) decreased ECF drainage, including spontaneous ECF closure in one patient, but larger multicenter trials are warranted to confirm these findings [50].

●Pancreatic enzymes – If patients have pancreatic insufficiency, pancreatic enzyme replacement may reduce fistula output [44]. (See "Chronic pancreatitis: Management", section on 'Pancreatic enzyme replacement therapy'.)

●Treating bacterial overgrowth – In some short gut and ECF/EAF patients, bacterial overgrowth may also need to be treated, especially when there is dilation of the upstream bowels. (See "Small intestinal bacterial overgrowth: Management".)

Endoscopic or interventional fistula closure — Interventional radiology and endoscopic methods of fistula closure are best suited for low-output, narrow-channel, longer ECFs with no evidence of infection, inflammatory bowel disease, or distal obstruction [6]. These interventions are also preferred in high-surgical-risk patients.

●Endoscopic clips, suturing, and stents – For patients with acute fistulas, particularly in the gastric, duodenal, and colonic locations, endoscopic clip application with through-the-scope (smaller defects) or over-the-scope clips (larger defects) can be attempted with the goal of luminal mucosal apposition to seal the fistula (figure 2) [51,52]. Additional endoscopic approaches include the use of endoscopic suturing devices or stents to close the ECF. Endoscopic techniques have a lower success rate in the closure of chronic ECF but can be attempted as the risks are very low (table 6).

●Tissue sealants, fistula plugs, and laser treatment – For patients with low-output and small ECFs, and particularly for patients with medical comorbidities who are not surgical candidates, fistula closure with fibrin, tissue sealants, and cyanoacrylate as well as other non-surgical techniques by interventional radiology has a high success rate (table 6). Such treatment often requires multiple sessions, with reported success rates ranging from 40 to 100 percent, with higher success rates associated with single-tract, small-orifice, low-output ECF without complex connections [6,53].

Most patients require a multimodal approach as monotherapy is less effective. Cyanoacrylate has stronger adhesion properties and is not degraded by intestinal or pancreatic enzymes [54,55]. Tissue sealant or cyanoacrylate injection is usually combined with procedures to ablate the epithelialized fistula tract (eg, laser ablation or brush abrasion [56]). Fistula plugs are also used as an additional modality for non-surgical treatment of ECF with variable success rates (25 to 75 percent) dependent on anatomic location and ECF output [57].

Surgical fistula closure — ECF/EAF may be closed surgically after careful consideration of all factors, including the patient's clinical status and comorbidities, the location and volume of output of the ECF/EAF, and time from the last surgical intervention if it is a postoperative fistula. With surgery, there is a high risk of ECF recurrence and of surgical complications related to a hostile abdomen with extensive adhesions and a high risk of enterotomy.

●Timing – In patients who develop an acute ECF/EAF within two weeks of initial surgical intervention, early reoperation to repair or resect the fistula may be considered if the patient is an appropriate surgical candidate at that time.

In chronic ECF/EAF patients with no evidence of intestinal obstruction, non-surgical attempts may be made to close the fistula. Otherwise, conservative management of ECF/EAF can be continued for a duration of 6 to 12 months. The wait permits dense intraperitoneal adhesions to become more favorable for surgical adhesiolysis, which can decrease rates of inadvertent enterotomy during re-laparotomy.

●Techniques – If surgical closure is carried out, ECF/EAF resection is the best course of action. The area of bowel involved with the ECF/EAF should be completely resected back to normal intestine. In a study of 205 patients undergoing ECF surgery, multivariate analysis confirmed that ECF recurrence was higher after oversewing the ECF than ECF resection (36 versus 16 percent) [58].

●Management of ECF with associated abdominal wall hernia – Patients who have an ECF/EAF with an associated large abdominal wall hernia are a significant challenge, especially those who still have prosthetic mesh in place [59]. In a review of 170 elective hernia repairs with ECF takedown by surgeons participating in the Abdominal Core Health Quality Collaborative (ACHQC), 62 percent had small bowel ECFs [60]. Most patients underwent ECF resection and hernia repair with sublay mesh placement (more biologic than permanent synthetic) and 40 percent required myofascial release. Morbidity was high with a surgical site infection rate of 22 percent. There were four reoperations for recurrent fistula and one mortality. One-year follow-up confirmed a hernia recurrence rate of 52.6 percent.

There is significant controversy regarding the issues of staged approaches to complex abdominal wall reconstruction for large hernias that are identified during intra-abdominal operations performed for a completely separate indication [61-63]. In patients with both ECF and large abdominal wall hernia, the definitive abdominal wall reconstruction should be performed after the patient has recovered from ECF closure, or in a staged approach with an open abdomen or temporary abdominal closure if any of the following is present [60,64]:

•Gross contamination.

•Hemodynamic instability or inability to tolerate increased time in the operating room (eg, hypoxemia, cardiac issues).

•High risk for re-laparotomy (ie, anastomotic leak, bleeding, future ostomy reversal).

•Extensive visceral and abdominal wall edema during ECF repair.

•Need for second-look laparotomy if there are concerns for intestinal ischemia.

•The surgeon performing ECF repair is not comfortable with abdominal wall reconstruction.

•The patient is not yet a suitable candidate for abdominal wall reconstruction (eg, major cardiopulmonary disease, smoker, body mass index >35 kg/m², or poorly controlled diabetes with hemoglobin A1C >8 percent).

●Management of associated inflammatory bowel disease – ECF surgery in patients with inflammatory bowel disease is also very challenging; other options for repair (eg, endoscopic) should be considered first. In 23 patients who had resection or repair for Crohn duodenal fistula, postoperative complications occurred in 48 percent, including anastomotic leak in 22 percent and duodenal fistula recurrence in 13 percent [65].

●Postoperative management – Postoperatively, patients should be kept on strict bowel rest and PN support until the return of bowel function with no evidence of ECF recurrence. All patients should wear an abdominal binder, which helps with postoperative pain control and provides abdominal wall support and early ambulation; patients should also refrain from heavy lifting. Drain output should be monitored closely for output volume and character as recurrent fistula risk is high.

●Surgical outcomes – A 2022 systematic review and meta-analysis of 53 studies reported that, overall, 72.5 percent of ECF patients underwent surgery to close the fistula [7]. ECF/EAF closure was successful in 89 percent of patients, but 11 percent developed a recurrent fistula after initial successful treatment.

Mortality rates related to ECF have significantly decreased over the last decades, from 40 percent [66,67] to <15 percent in most contemporary series [68-71], and to 8.5 percent in the 2022 systematic review [7]. Some reports of definitive ECF surgical closure have no reported mortality [72].

In the 2022 systemic review, analysis of the subgroup of ECF/EAF patients who required both ECF takedown and abdominal wall reconstruction for ventral hernia (n = 315) confirmed that 78 percent achieved fascial closure, and 72 percent required mesh placement [7]. Ventral hernia recurrence was 19.7 percent and ECF/EAF recurrence was 7.6 percent.

INFORMATION FOR PATIENTS — 

UpToDate offers two types of patient education materials, "The Basics" and "Beyond the Basics." The Basics patient education pieces are written in plain language, at the 5^th to 6^th grade reading level, and they answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials. Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are written at the 10^th to 12^th grade reading level and are best for patients who want in-depth information and are comfortable with some medical jargon.

Here are the patient education articles that are relevant to this topic. We encourage you to print or e-mail these topics to your patients. (You can also locate patient education articles on a variety of subjects by searching on "patient info" and the keyword(s) of interest.)

●Basic topics (see "Patient education: Enteric fistula (The Basics)")

SUMMARY AND RECOMMENDATIONS

●Definitions – A fistula is an abnormal connection between two body parts or organs. Enterocutaneous fistulas (ECFs) communicate between the lumen of the gastrointestinal tract and the skin. Enteroatmospheric fistulas (EAFs) communicate between the lumen of the gastrointestinal tract and an open abdominal wound. (See 'Introduction' above.)

●Etiologies – The majority of ECFs/EAFs occur in the postoperative setting, usually because of a bowel anastomotic leak or missed enterotomy. Approximately 20 to 30 percent of ECFs arise spontaneously, most commonly due to Crohn disease. (See 'Etiology and pathogenesis' above.)

●Presentation – Most patients with an ECF/EAF are postoperative and have not had normal, expected recoveries. Common postoperative complications include surgical site infection, abdominal abscesses, fascial dehiscence, anastomotic leak, and the need for an open abdomen approach. (See 'Patient presentation' above.)

●Diagnosis – Bilious drainage from a wound on the abdomen is concerning for a possible ECF/EAF, and drainage of enteric contents from an open abdominal wound is diagnostic of an ECF. The diagnosis of EAF requires visualization of leakage of enteric contents from a bowel segment, usually only possible in an open wound or open abdomen. (See 'Diagnosis' above.)

●Management – "SNAP" is a pneumonic for the four steps of ECF/EAF management:

•Sepsis control and skin care – In septic patients, broad-spectrum, empiric antibiotics that cover potential enteric pathogens should be started within 60 minutes. Any intra-abdominal source of sepsis revealed by imaging should be controlled as quickly as possible with percutaneous drainage, minimally invasive drainage, or open drainage.

Most patients with low-output (<200 mL per day) ECF and good skin integrity can be managed with a wound manager or ostomy appliance. For patients with high-output ECF (>500 mL per day) or EAF, skin management is more nuanced and may require negative pressure wound therapy (NPWT). (See 'Sepsis control' above and 'Skin care' above.)

•Nutritional support – Parenteral nutrition (PN) is commonly initiated first in high-output ECF/EAF patients. Depending on the fistula output, enteral nutrition may be slowly introduced (table 2). (See 'Nutrition support' above.)

•Anatomy definition (diagnostic evaluation and imaging) – Abdominopelvic CT with enteral and intravenous contrast is the initial diagnostic imaging modality. A CT fistulography may be added to evaluate the bowel distal to the ECF/EAF if most enteral contrast drains out the fistula site. (See 'Anatomy definition' above.)

•Patience and planned procedure to close fistula – After initial diagnosis and stabilization, options for further management include conservative management hoping for spontaneous closure versus non-surgical or surgical closure (table 4). (See 'Patience and planned procedure to close ECF' above.)

-Initial conservative management for all patients – The volume of the fistula output can be controlled with restriction of hypo-osmolar fluid intake. For patients with persistent fistula output >500 mL per day, we suggest a combination of antimotility agents and antisecretory agents (Grade 2C). We typically start with loperamide and a proton pump inhibitor (PPI) (table 5 and algorithm 2). (See 'Conservative management' above.)

-Early interventional or endoscopic management in select patients – Invasive interventional and endoscopic fistula closure methods are best suited for low-output, narrow-channel, longer ECFs/EAFs without any evidence of infection, inflammatory bowel disease, or distal obstruction, or in poor surgical candidates (figure 2 and table 6). (See 'Endoscopic or interventional fistula closure' above.)

-Delayed surgical management for those who have refractory fistulas – Surgical closure is commonly delayed for approximately six months to one year in anticipation of extensive adhesiolysis. The area of bowel involved with ECF should be completely resected back to normal intestine rather than primary repair. Concomitant abdominal wall reconstruction should be deferred or staged in the presence of contamination or complication. (See 'Surgical fistula closure' above.)

ACKNOWLEDGMENT — 

The UpToDate editorial staff acknowledges William Schecter, MD, and Sharon L Stein, MD, FACS, FASCRS, who contributed to an earlier version of this topic review.