Intestinal Anastomosis

Intestinal anastomosis is a surgical procedure performed to establish communication between two formerly distant portions of the intestine. This procedure restores intestinal continuity after removal of a pathologic condition affecting the bowel. Intestinal anastomosis is one of the most commonly performed surgical procedures, especially in the emergency setting, and is also commonly performed in the elective setting when resections are carried out for benign or malignant lesions of the gastrointestinal (GI) tract.

A disastrous complication of intestinal anastomosis is anastomotic leakage resulting in peritonitis, which is associated with high morbidity and mortality. Proper surgical technique and adherence to fundamental principles are imperative to ensure successful outcome after intestinal anastomosis.

Intestinal anastomosis can be performed by means of a handsewn technique that uses absorbable or nonabsorbable sutures or by means of stapling. The former is the more commonly used option because of the availability and affordability of suture materials and the wide familiarity with the procedure. The increased availability of stapling devices for intestinal anastomosis has provided an alternative option for performing a rapid anastomosis. Higher cost, limited availability, and less familiarity are the main drawbacks of these devices.

Less common techniques for intestinal anastomosis use compression devices (biofragmentable anastomotic rings), glue (tissue or synthetic), and laser welding. ^{[1, 2, 3, 4]}

Newer techniques include robotic-assisted methods and magnetic compression anastomosis. In an initial case series from the first trial of the Magnamosis magnetic compression anastomosis device in humans, the device was successfully placed and effectively formed a side-to-side anastomosis (which essentially is a functional end-to-end small-bowel anastomosis). ^[5] No leaks were found in the intermediate follow-up period.

Advances in therapeutic endoscopy have led to the development of minimally invasive techniques that can be performed instead of surgical interventions to create GI anastomoses. Studies have reported the use of endoscopic ultrasonography (EUS)-guided visceral anastomosis for applications such as bypassing malignant and benign gastric outlet obstruction and relieving pancreatobiliary symptoms in afferent loop syndrome. ^[6]

Intestinal anastomosis in neonatal and pediatric patients may be required for the management of many conditions. Some conditions may necessitate resection of pathology followed by primary anastomosis, whereas other conditions may necessitate delayed anastomosis. Intestinal anastomosis may also be necessary in the management of some nonintestinal anomalies.

Restoration of bowel continuity after resection of diseased bowel

Resection of diseased bowel is performed in the following settings:

• Bowel gangrene secondary to vascular compromise resulting from mesenteric vascular disease, prolonged intestinal obstruction, intussusceptions, or volvulus
• Malignancy
• Benign conditions, such as intestinal polyps, intussusception, or roundworm infestation with intestinal obstruction
• Infections, such as tuberculosis complicated with stricture or perforation
• Traumatic perforations
• Large perforation (traumatic) not amenable to primary closure
• Radiation enteritis complicated with bleeding, stricture, or perforation
• Inflammatory bowel disease (IBD),  ulcerative colitis (UC), or Crohn disease (CD) when disease is refractory to medical therapy or associated with complications such as bleeding, perforation, toxic megacolon, or dysplasia/carcinoma
• Chronic constipation, idiopathic slow-transit constipation, or Hirschsprung disease, for which subtotal colectomy may be performed when the disease is refractory to medical therapy

Bypass of unresectable diseased bowel

Bypass of unresectable diseased bowel is performed in the following settings:

• Locally advanced tumor causing luminal obstruction
• Metastatic disease causing intestinal obstruction
• Poor general condition or condition that prevents major resection

Pediatric conditions

Pediatric conditions for which intestinal anastomosis may be required include the following:

• Congenital anomalies, such as Meckel diverticulum, intestinal atresia, malrotation with volvulus leading to gangrene, meconium ileus, duplication cysts, and Hirschsprung disease
• Inflammatory conditions, such as necrotizing enteritis, enterocolitis, tuberculosis, and enteric perforation
• Other conditions, such as intussusception, angiodysplasia, polypoid disease, and ascariasis
• As a part of other surgical procedures, such as Kasai portoenterostomy, choledochal cyst surgery, urinary diversions, and excision of pancreatic neoplasms

Intestinal anastomosis is contraindicated in conditions where there is a high risk of anastomotic leakage, such as the following:

• Severe sepsis
• Poor nutritional status (eg, severe hypoalbuminemia)
• Disseminated malignancy (multiple peritoneal and serosal deposits, ascites)
• Viability of bowel in doubt
• Fecal contamination or frank peritonitis
• Unhealthy bowel condition (precludes primary anastomosis)

Best practices

The following are essential for good intestinal anastomosis:

• Adequate exposure and access
• Gentle handling of the bowel
• Adequate hemostasis
• Approximation of well-vascularized bowel
• Absence of tension at anastomosis
• Good surgical technique
• Avoidance of fecal contamination

Procedural planning

Although an inverting anastomosis has been found to be better than an everting anastomosis, there is no difference in complication rates between single-layer and double-layer techniques or between continuous and interrupted anastomosis.

Stapled anastomotic technique has virtually replaced handsewn technique for low colorectal anastomoses, and its use in other areas has also increased. Although stapled anastomosis has not yet been proved superior to handsewn anastomosis, it has definitely reduced the operating time and made the procedure easier, especially in low colorectal anastomosis. However, a 2017 study by Kosuge et al reported that in colonic surgical procedures, a triangulating stapled anastomosis appears to be superior to other stapling methods or handsewn anastomoses with regard to leakage. ^[7]

Although restoration of bowel continuity is generally preferred, a decision must be made judiciously in emergency settings. A staged procedure may be preferred for restoration of bowel continuity if the general condition of the patient is not good enough to avoid the complications associated with anastomotic leakage.

Complication prevention

An important component of preventing complications related to intestinal anastomosis is complete preoperative optimization of patients' medical status, including correction of malnutrition with nutritional support and treatment of associated systemic illness. However, this is generally possible only in elective resections, not in emergency situations.

The best practices listed above can also help prevent complications.

It is very important to prevent hypothermia and hypovolemia during surgery, especially in children. Thermal mattresses should be used for thermoregulation, especially for neonates. Fluid loss should be minimized, and any fluid lost should be adequately replaced. An adequate supply of blood should be arranged.

A meta-analysis on delayed coloanal anastomosis determined that if the anastomosis is delayed, a coloanal anastomosis with a diverting stoma can be avoided. ^[8] This study did not show any raise in perioperative complications (eg, anastomotic leakage, postoperative ileus, pelvic abscesses, or sepsis) with delayed anastomosis.

In a study (N = 2593) examining the effect of indocyanine green (ICG) fluorescence angiography in preventing anastomotic leakage after rectal cancer surgery, Li et al found that the anastomotic leakage rate in the ICG group was significantly lower than that in the non-ICG group. ^[9] The ICG group also had lower complication rates.