By : Kinjal Banerjee SU-6

INTRODUCTIONINTRODUCTION

Fistula is defined as an abnormal communication between two epithelialized surfaces.

Enterocutaneous fistula is an abnormal communication between the skin with various parts of the gut, for example duodenum, jejunum etc.

The word fistula means a “pipe” or “flute” in Latin.

The ileum is the most common site of origin of Enterocutaneous fistula.

DISCUSSIONDISCUSSION

Patients are usually systemically ill, with sepsis being a significant risk factor.

Spontaneous closure rate depend upon many factors like anatomy, etiology, nutritional status, output from fistula.

Fluid and electrolyte imbalance, malnutrition, sepsis & related complications, local wound excoriation are some of the known complications.

ETIOLOGYETIOLOGY

Webster and Carey proposed five mechanisms of fistula formation :

1> Congenital : - Rare

- Due to the complete failure of Vitellointestinal duct to obliterate.

- Fecal matter at umbilicus after post natal slough of the stump.

2> Trauma : - Major penetrating trauma to the abdomen may lead to ECF.

- Damage control laparotomy techniques have higher risk of delayed ECF formation(2% to 25%).

3> Infection : - Abscess or invasive intestinal infections like amoebiasis, coccidiomycosis, tuberculosis etc.

- Intestinal perforation in ileum from tuberculosis or enteric fever esp in 3rd world countries.

- Actinomyces infection post appendectomy.

4> Perforation or Injury with Abscess & Operative complications :

- Intra-abdominal abscess may erode into the gut & through the skin.

- 75-85% are iatrogenic - after surgery for bowel obstruction, cancer, or IBD

5> Inflammation, Irradiation or Tumour :

- Crohn’s disease may cause ECF – post op more common than spontaneous.

- ECF after anastomosis/appendicectomy/simple exploration in Crohn’s disease. - Irradiation for pelvic malignancies etc may lead to a chronic non-healing ECF.

PREVENTION OF FISTULAPREVENTION OF FISTULA

- Acute intra-operative perforations should be identified and closed.

- Serosal tears should be examined carefully and repaired if required.

- Aggressive interloop adhesion break-up should be avoided to prevent serosal tears.

-Post operatively anastomotic leaks/unrecognised perforations and subsequent fistulae may manifest as instability or patient’s failure to improve.

-Fever, abdominal pain followed by exiting of intestinal contents from drain or incision site.

-Occasionally,heavily purulent discharge may mask an ECF like in enteric perforations.

-Activated charcoal or indigo carmine by mouth can help in diagnosing ECF.

- Intraluminal instillation of methylene blue and saline or direct endoscopy helps to identify small perforations.

DIAGNOSIS OF PERFORATION AND FISTULADIAGNOSIS OF PERFORATION AND FISTULA

STAGING AND CLASSIFICATIONSTAGING AND CLASSIFICATION

1. Anatomical Classification : Internal or External fistula(ECF).

- Internal fistulae are named after the structures it communicates like gastrocolic, jejunoileal, aortoenteric fistula.

- External fistulae like gastric, duodenal, jejunal, ileal or fecal.

2. Physiologic classification : Based on output

- High-output > 500 cc/day (Difficulties in fluid management and skin care) - Moderate-output 200-500 cc/day

- Low-output < 200 cc/day (Usually colonic)

Stabilization

Control of Sepsis and appropriate Skin care

Nutrition

Define underlying Anatomy

Plan to deal with the fistula

MANAGEMENTMANAGEMENT

S-S-N-A-PS-S-N-A-P

STABILIZATIONSTABILIZATION

> The first step of management is the resuscitation and stabilization of the patient.

> Needs to be accomplished within the first 24 to 48 hours of management.

> Initial efforts directed towards intravenous fluid resuscitation, control of infection, protection of surrounding skin & measuring and replacing ongoing losses.

> Attention should also be given to any intra-abdominal/subcutaneous abscesses & if present they should be drained.

A. RESUSCITATIONA. RESUSCITATION

> Restoration of normal circulating blood volume and correction of electrolyte and acid-base imbalances are a top priority.

>Rehydration usually requires isotonic fluid(NS/RL) until the patient is euvolemic.

> Strict input and output measurements are essential and CVP monitoring and urinary catheterisation are especially helpful.

> Ongoing fluid losses should be fully replaced and electrolyte imbalances must be corrected.

RESUSCITATION CONTD..RESUSCITATION CONTD..

> Enterocutaneous fistulae are usually associated with hypokalemia and metabolic acidosis, which require correction.

> Electrolyte measurement of the fistula output helps in planning of replenishment of ongoing losses.

> Urine output should be restored to greater than 0.5mL/kg/hr.

> Requirement of blood transfusion depends upon overall hemodynamic status, patient’s oxygen carrying capacity and oxygen delivery.

B. NUTRITIONB. NUTRITION

> In 1972, Roback and Nicholoff reported closure of 73% of enteric fistulae in adequately nourished patients, as against 19% in inadequate ones.

> Nutritional support needs to begin as soon as the patient is stabilized.

> Nutrition can be given by parenteral or enteral route,based on the anatomy of the fistula.

> Its advisable to provide atleast a part of the daily nutritional requirement through enteral route.(Even 25% of daily requirement given enterally, can help reap its benefits)

NUTRITION CONTD..NUTRITION CONTD..

> Nutrition via the enteral route helps in maintaining the intestinal mucosal barrier, more efficacious delivery of nutrients, stimulating hepatic protein synthesis.

> WHO’s ORS (40g/L of glucose, 90 mEq/L of Na, 20 mEq/L of K) should be given when oral intake is possible.

> In proximal fistulae, the enteral feeding tube may be entered beyond the fistula to provide enteral nutrition(fistuloclysis).

> It is advisable to enter feeding tube beyond ligament of Treitz for a gastric or duodenal fistula.

NUTRITION CONTD..NUTRITION CONTD..

> Enteral feeds of highly absorbable, low-residue nutrients can be given if even 4ft of functional bowel exists in between ligament of Treitz and the proximal end of the fistula.

> During the time the enteral nutrition is increasing, patient should be supplemented with TPN.

> TPN is also given in patients who do not tolerate enteral feeds or have long standing ileus or before fistulous tract is well established.

NUTRITION CONTD..NUTRITION CONTD..

> Twice the daily requirement of vitamins, trace elements, zinc and upto 10 times the daily requirement of Vitamin C should be provided.

> Short turnover proteins like retinol-binding protein, prealbumin, ferritin can be used to monitor the weekly efficacy of protein delivery. [Alb half life is 20 days].

> Mortality rate of 42% with alb <2.5 mg/dl vs 0% if >3.5 mg/dl.

TYPE OF FISTULA CALORIE REQ PROTEIN REQ

Low Output 30-35 kcal/kg/day 1-2 gm/kg/day

High Output 45-50 kcal/kg/day 1.5-2.5 gm/kg/day

C. CONTROL OF SEPSIS AND FISTULA EFFLUENTC. CONTROL OF SEPSIS AND FISTULA EFFLUENT

> Persistant fever, tachycardia and leukocytosis along with failure to improve adequately points towards possible sepsis or abscesses.

> May require surgical drainage of abscess,if any along with adequate antibiotic cover.

> Local skin care and prevention of skin excoriation by using stomahesive paste or aluminium paint etc along with stoma bags.

> Excessive fistula output can be controlled by nasogastric tube placement, withdrawal of oral feeds, initiation of parenteral nutrition or placement of sump suction catheter as described by Suripaya and Anderson,1971.

C. CONTROL OF SEPSIS AND FISTULA EFFLUENT CONTD..C. CONTROL OF SEPSIS AND FISTULA EFFLUENT CONTD..

> Vacuum assisted closure [VAC] device drainage system maybe used too.

> Due to the negative pressure application, VAC device helps to control drainage, minimizes the size of the abdominal wound, reduces frequency of dressing and protects the skin while helping to promote fistula healing.

> For majority of ECFs, VAC devices have become the method of choice for controlling fistula drainage and skin protection.

D. PHARMACOLOGICAL SUPPORTD. PHARMACOLOGICAL SUPPORT

> Somatostatin analogue Octreotide, at doses of 100 – 250 mcg TDS reduces fistula output by 40 – 60% by the end of 24 hrs.

> Should be discontinued if ineffective for 48 hrs as it has side effects like hyperglycemia, elevated cholesterol and reduced bowel motility.

> Octreotide and TPN seem to have a synergistic effect on reduction of effluent volume and improvement in fistula closure rates.

> Proton-pump inhibitors and H2 receptor antagonists also help reduce fistula output especially in proximal fistulas.

D. PHARMACOLOGICAL SUPPORT CONTD..D. PHARMACOLOGICAL SUPPORT CONTD..

> Cyclosporine in doses of 4 mg/kg/day for 6 – 10 days followed by oral doses of 8 mg/kg/day helps to treat refractory fistulae associated with Crohn’s disease.

> Other drugs used include Tacrolimus, Azathioprine, 6-MP, Infliximab(mAb TNFα).

> Infliximab administered at a dose of 5 mg/kg iv at 0,2,6 weeks helped in partial resolution of 68% of multiple lesions and complete closure in 55% of patients.

> Complications include URTI, headache, fatigue etc.

INVESTIGATIONSINVESTIGATIONS

> Investigations are done for the next 7 to 10 days following stabilization.

> They are carried out to determine the presence and location of the fistula, its cause and presence of comorbidities.

> Oral administration of Indigo Carmine/ Charcoal helps in diagnosing the presence of a fistula,but not its location, cause or anatomy.

> USG abdomen helps in locating intra-abdominal abscesses, apart from helping in performing guided aspiration of intra-abdominal collections.

> Fistulography helps in defining the length & width of the fistula, its anatomical location, the presence of any distal obstructions etc.

> It can be performed by entering a small cathter into the fistulous tract and then injecting the water-soluble contrast under fluoroscopy.

> Fistulogram should be performed before an upper GI series or CT scan with oral contrast or contrast enema as it poses difficulty in interpretation.

> Fistulography should be followed up with a complete contrast study of the GI tract.

CT scan of the abdomen with IV and oral contrast is highly sensitive and specific for locating the fistula, defining its anatomy, commenting on the gut surrounding fistula, presence of any intra-abdominal abscess or distal obstruction/pathology.

CT scan is highly recommended for duodenal and pancreatic fistula.

CT scan can be therapeutic by helping in CT-guided aspiration of intra-abdominal abscesses,if any.

Endoscopy may also be used occasionally though its principal use is in internal fistulas.

Endoscopy is usually delayed till acute inflammation gets reduced.

DECISIONDECISION

Factor Favorable Unfavorable

Organ of origin Esophageal, Duodenal stump, Pancreatic, Biliary, Jejunal, Colonic

Gastric, Lateral duodenal, Ligament of Treitz, Ileal

Etiology Postop (anast leak), Appendicitis, Diverticulitis

Malignancy, IBD

Output Low (<200-500cc/day) High (>500cc/day)

Nutritional status Well nourished, Transferrin >200

Malnourished, Transferrin <200

Sepsis Absent Present

State of bowel Intestinal continuity, absence of obstruction

Diseased adjacent bowel, Distal obstruction, Abscess, Discontinuity, Irradiation

Fistula characteristics

Tract >2 cm, Defect <1cm Tract <1cm, Defect >1cm

Miscellaneous Original operation at same institution

Referred from outside institution

FACTORS RESPONSIBLE FOR SPONTANEOUS CLOSURE

> Reber et al reported that more than 90% of small intestinal fistula which closed spontaneously,did so within a month.

> Spontaneous closure rates dropped to less than 10% after 2 months and none after 3 months.

> Factors possibly responsible for failure of spontaneous closure are: a. Foreign Body b. Radiation c. Inflammation/ infection d. Epithelialisation [F-R-I-E-N-D-S] e. Neoplasm f. Distal intestinal obstruction g. Steroids.

DEFINITIVE THERAPYDEFINITIVE THERAPY

> Majority (80-90%) will close within 6 weeks with conservative management.

> Surgery between 10 days and 6 weeks post-op will encounter the worst adhesions.

> Preferably wait upto 6 weeks before open exploration and repair of defect, but in case of faecal fistula, due to intense inflammation, it is prudent to wait upto 10-12 weeks.

> The patient should,by then, be nutritionally optimized, patient should not be septic and patient should be vitally stable.

> Definitive operative correction remains the final step in the treatment of non-healing small intestinal fistulas.

> In majority of the cases, preferred operation is resection of the involved segment with primary end-to-end anastomosis. (Reber HA, 1978)

> However if primary anastomosis is not possible,then both the proximal and distal ends of intestine are exteriorized.

> In case the fistula is deemed inappropriate for resection, such as when it develops after a deep pelvic procedure, staged approach involving bypass should be considered.

> In a staged procedure, the fistulous segment is left in-situ or the ends are exteriorized as mucous fistula and the afferent and efferent bowel loops are anastomosed to restore intestinal continuity.

> The staged procedure is completed when the fistula segment is removed at a later date,although it may not always be possible.

> Enteroatmospheric fistulas, which are associated with large abdominal defects are very difficult to manage and are associated with high mortality rates.

> Mortality rates may vary from 20% to 60%. (Schein M, Decker GA 1991)

> Enteroatmospheric fistulas usually require multiple staged operations.

ENTEROATMOSPHERIC FISTULAENTEROATMOSPHERIC FISTULA

> Enterocutaneous fistula treatment is complicated due to various factors like open abdominal wound leading to desiccation of gut loops, presence of multiple fistulous openings, dressings adhering to the gut loops etc.

> VAC devices are used initially to approximate the large abdominal defect along with isolation of the fistula(s) by ostomy bags.

> After proper granulation tissue formation, the stabilized patient can be considered for SSG, if his nutritional status is favourable.

> After 6 to 12 months recovery time to replenish protein and calorie stores, resection of the fistula as definitive therapy can be provided to the patient.

> Musculocutaneous flaps, abdominal wall reconstruction by component separation technique, use of prosthetic materials,esp biologics may also be necessary. (human acellular dermal matrix)

> In 1995, Ho HS and Frey CF used primary closure of gastric fistula with delayed external drainage as treatment for gastric fistulas.

> If the gastric fistula defect is too large to allow primary closure,then a Roux-en-Y gastrojejunostomy may be done.

> Duodenal fistulas are usually treated with tube duodenostomy or Roux-en-Y duodenojejunostomy.

> A feeding jejunostomy distal to the enteroenterostomy should always be considered.

Roux-en-Y DuodenojejunostomyRoux-en-Y Duodenojejunostomy

CONCLUSIONCONCLUSION

> Enterocutaneous fistulas are abnormal communication between the gut and skin.

> Majority of the ECF are due to iatrogenic causes (70-85%). Others include trauma, congenital causes. Spontaneous ECF may arise due to Crohn’s disease.

> Malnutrition, Electrolyte imbalances, acid-base imbalances and sepsis are the major causes of mortality in ECF.

> After initial stabilization of the patient by resuscitation( fluid, electrolytes, blood transfusions etc), the patient is subjected to various investigations to determine the location& anatomy of fistula, presence of distal obstruction etc.

> Enteral nutrition is always preferable to parenteral nutrition provided the patient tolerates enteral feeds.

> Local wound care by application of ostomy bag and pastes are essential.

> Drainage of intra-abdominal abscesses, treatment of sepsis is of utmost importance.

> After proper optimization, patient undergoes definitive therapy which includes resection of the fistulous segment of the gut.

> ECF with large abdominal defects may require VAC devices/ biologic mesh SSG to help close the defect.

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