Enteroenterostomy

Enteroenterostomy is an anastomosis between one part of the small bowel and another part of the small bowel (jejunum or ileum). It is used to restore bowel continuity after resection of a segment of the bowel or after creation of a Roux-en-Y loop of jejunum or as a part of a Braun loop of jejunum. When performed as a bypass procedure, enteroenterostomy relieves bowel obstruction. ^{[1, 2]}

An enteroenterostomy is more often performed in an emergency setting (eg, obstruction or trauma) than in an elective setting.

Enteroenterostomy is indicated for the following:

• After resection of small intestine (eg, for inflammatory bowel diseases such as tuberculosis, Crohn disease, malignancy [primary of the small bowel, such as adenocarcinoma or lymphoma; infiltration of the small bowel by a malignancy of an adjacent organ, such as the colon], ischemic stricture, trauma)
• For intestinal bypass (short circuit) to relieve obstruction (though it is not preferred, in that it may result in blind-loop syndrome) or after closure of a perforation (eg, an enteric perforation from typhoid)
• As a part of a Roux-en-Y loop or Braun loop of jejunum (used for biliary-enteric, pancreaticoenteric, or esophagoenteric anastomosis and as a part of gastric bypass as a bariatric procedure) ^{[3, 4, 5, 6, 7]}
• Braun enteroenterostomy is a side-to-side anastomosis between the afferent and efferent limbs of jejunum distal to a biliary-enteric, pancreaticoenteric, esophagoenteric, or gastroenteric anastomosis, diverting the jejunal anastomosis from the aforementioned anastomoses 
• Endoscopic ultrasonography (EUS)-guided enteroenterostomy (EUS EE) has been reported to be effective in the management of afferent loop syndrome following a gastrectomy or gastrojejunostomy recontruction ^[8]

Contraindications for enteroenterostomy include the following (which are contraindications for performing any bowel anastomosis in general):

• Poor nutritional status (severe pallor, pitting pedal edema, low serum albumin levels)
• Significant hypotension during operation, irradiated bowel
• Poor blood supply to the bowel ends
• Thick edematous obstructed or inflamed bowel ends (sutures cutting through)

In case of doubt, it is better not to anastomose but rather to exteriorize (loop stoma for a perforation and proximal stoma and distal mucous fistula after resection).

Best practices

Several steps can help promote better outcomes during enteroenterostomy:

• No tension (though tension is usually not a problem in the small bowel unless its mesentery is shortened, thickened, and inflamed)
• Good blood supply of the bowel ends - This may require resection of a larger segment of bowel or repeat resection of a doubtfully viable bowel
• Good (water-tight) approximation
• No mucosal eversion between approximated bowel walls; the mucosa should be intentionally inverted - This can be achieved by avoiding mucosa or taking a very small amount of mucosa in suture bites
• Serosa (visceral peritoneum) should be approximated
• In case of an end-to-end enteroenterosotomy, the mesenteric angle (bare area) should be carefully covered with peritoneum - This can be done by taking a U (box) stitch that includes both layers of small-bowel mesentery.
• No distal obstruction

Procedural planning

Most small-bowel anastomoses are performed in the emergency setting in patients with intestinal obstruction. A nasogastric tube is inserted to decompress the stomach (and proximal dilated small bowel). Fluid and electrolyte imbalances should be corrected. Intravenous (IV) human albumin (100 mL of 20% albumin twice a day) may be used to increase the oncotic pressure and take care of the bowel wall edema. Bowel preparation is not required for small-bowel resection and anastomosis (as opposed to large-bowel resection and anastomosis, in which bowel preparation is required).

Complication prevention

An anastomotic leak is a life-threatening complication that can cause sepsis (fever, tachycardia, hypotension), abdominal signs of guarding and tenderness, multiple organ dysfunction syndrome (MODS), and even death (mortality, 10-15%). The leak is initially small but results in a local abscess that erodes into the rest of the anastomosis or spreads into adjacent structures (including vessels) to cause bleeding.

A localized leak manifests as undue or prolonged pain, unexplained fever, and unsettled abdomen with localized tenderness and paralytic ileus. A major free leak causes peritonitis; it may also present as an enterocutaneous fistula (ie, enteric contents protruding through the wound) or wound disruption (dehiscence)

Because an anastomotic leak is difficult to detect in obese and elderly patients, a high index of suspicion is necessary. In case of doubt, it can be confirmed by means of computed tomography (CT) with IV and oral (water-soluble) contrast (Gastrografin).

Anastomotic leakage almost invariably necessitates reoperation; dismantling of anastomosis and exteriorization (proximal stoma and distal mucous fistula) should be performed. No sutures should be used in an attempt to close (repair) the anastomotic leak, because the sutures are unlikely to hold and tend to cut through, further enlarging the leak.

Other potential complications include the following:

• Anastomotic narrowing caused by too much inversion of walls - This is likely to be a greater problem in a two-layer end-to-end anastomosis
• Blind-loop syndrome in bypass and side-to-side anastomosis

An enteroenterostomy restores bowel continuity after resection of a segment of the bowel or after creation of a Roux-en-Y loop of jejunum. When performed as a bypass procedure, enteroenterostomy relieves bowel obstruction.

Braun enteroenterostomy may reduce the risk of delayed gastric emptying (DGE) in pancreatoduodenectomy. ^[9]  A study by Watanabe et al found that the use of a lengthened efferent limb in a Braun enteroenterostomy decreased DGE by as much as 6%, leading to a shorter hospital stay. ^[10]