Enterocutaneous fistula

Section: Small bowel Curriculum: Curriculum, page 60

Definition

• An abnormal communication between small bowel and skin but often used broadly to include enteroatmospheric

Classification

• By source
  • Organ of origin (eg, gastro-, duodeno-, entero-, jejuno-, ileo-, colo-, recto-)
  • And
  • Point of its termination (eg, -cutaneous, -atmospheric
• By volume
  • Low-output
    • 200 mL/day.
  • Moderate-output
    • 200 and 500 mL/day.
  • High-output
    • 500 mL/day.

Pathogenesis

• Iatrogenic
  • Most common
  • Caused by anastomotic leaks, and unrecognized bowel injuries
  • Enteroatmospheric or exposed fistulas occur in the midst of an open abdomen with no overlying soft tissue
• Spontaneous fistula
  • “FRIEND” describes common etiologies for spontaneous enterocutaneous fistulas
    • Foreign body
    • Radiation, inflammation (eg, Crohn disease)
    • Infection (eg, tuberculosis, actinomycosis)
    • Epithelialization
    • Neoplasia
    • Distal obstruction

Management phases for enterocutaneous fistula

• SNAP
  • Stabilization and sepsis treatment
  • Nutrition + wounds + fluids + medications
  • Anatomy
  • Planning and psychological support

Stabilisation and sepsis treatment

Acute management

• 0-7 days
• Sepsis
  • Drainage of abscesses – either open or percutaneously
  • Treatment of sepsis with IVAbx.
• Stabilise
  • Fluids
  • Hemodynamics

Chronic management

Fluids

• Resuscitation and correction of fluid and electrolyte imbalances.
• The most common electrolyte imbalances are hyponatraemia, hypokalaemia and hypomagnesaemia
• Measurement of output – often requires a period of NBM.
• Fistula should be defined as high (>500), moderate (200-500) or low (<200).

Wound care

• Wound care needs to be addressed
  • Will often require assistance by the stomal therapist.
  • Bag drainage
  • Skin protection
• Negative pressure wound therapy can be used to manage the effluent - there is concern about forming new fistulas so have to be careful.

Nutrition

• Nutrition needs to be addressed – TPN or enteral nutrition.
  • Low rate of spontaneous healing if not nutritionally optimised
• Low output fistula’s
  • Generally can have enteral nutrition
  • Update authors algorithm
    • After the patient has been stabilized and ѕерsis treated, we generally try a short period of bowel rest (days) to see if the fistula output would reduce and/or if the fistula would spontaneously close. During this brief period of bowel rest, the patient may or may not need total parenteral nutrition (ТPΝ) depending on his/her baseline nutritional status.
    • If the fistula output does not decrease with bowel rest and the fistula does not close, the patient is then started on an oral diet while we continue to monitor and manage output. 
    • If the fistula output increases substantially with oral diet, we will generally stop oral diet and start ΤРN to see if that decreases output. ΤPN has been known to reduce fistula outpu
• Moderate and high output fistulas
  • Usually require TPN for nutrition

Medications to reduce output

• PPI
  • Decreased acidity of output.
• Octreotide
  • May be helpful although is costly, associated with tachyphylaxis and causes gallstones.
  • Can trial for three days to see if works
• Loperamide
  • Up to(40mg/day) and codiene (240mg/day)

Investigation

• CT with fistulogram will determine – location of the fistula, presence of an abscess, presence of intestinal obstruction, length of the fistula tract, size of the bowel wall defect, and the cause of the fistula.
• MRI is also useful at answering the above questions.

Planning

Will it close?

• Colonic fistulas typically close in 30-40 days.
• Small bowel fistulas close in 40-60 days (if at all).
  • Typically, only 1/3 of fistula’s close spontaneously.
• 90% of fistula’s will close within 4 sepsis free weeks - after 5-6 weeks unlikely

Factor	Likely to close	Unlikely to close
Anatomical location	- Oropharyngeal - Esophageal - Duodenal stump - Lateral duodenal - Pancreaticobiliary - Jejunal	- Gastric - Ligament of Treitz - Ileal
Tract length	>2 cm	<2 cm
Defect size	<1 cm2	>1 cm2
Fistula output	Decreasing	Stable or increasing
Surrounding bowel	- Healthy	- Distal obstruction or stricture - Abscess - Active inflammation - Bowel discontinuity
Etiology	- Appendicitis - Diverticulitis - Postoperative	- Crohn disease - Malignancy - Radiation - Foreign body (mesh)
Nutritional status	Well nourished	Malnourished
Sepsis	Absent	Present

Surgery

Timing of surgery

• Typically 6 weeks post fistula development is the worst time to operate due to adhesions.
• Typically 6-12 months as this allows the adhesions to become easier to dissect.
• Sometimes you may need to operate earlier if there is ongoing sepsis which cannot be percutaneously controlled – in this case you want to avoid doing an anastomosis and instead defunction them even if it means that have a high output jejunostomy.

Pre-operative preparation

• Patient needs to be nutritionally replete and recovered.
• Ideally albumin should be > 35
• Ideally the skin should be healthy so facilitate abdominal wall closure.
• The gut should be rested prior to surgery to reduce the stool volume
• Patients should be mentally prepared for the surgery
• Don’t put any other cases on your list for that day
• A plan may need to be made about abdominal wall closure i.e. ?component separation ?plastic surgery input

Intra-op management

• Incision should be placed remote from prior incisions
• The entire small bowel should be mobilised – starting from the easy place and ending at the hardest place (which is likely to be the fistula).
• The segment of bowel associated with the fistula will need to be resected.
• The anastomosis should be left away from any abscess cavity.
• The omentum should be placed between the anastomotic site and the abdominal wall.
• Drains may be left in abscess cavities
• A gastrostomy or feeding jejunostomy should be considered.