Intestinal Anastomosis 

Updated: Feb 18, 2020
Author: Vikram Kate, MBBS, MS, PhD, FRCS, FACS, FACG, FRCS(Edin), FRCS(Glasg), FIMSA, MAMS, MASCRS; Chief Editor: Kurt E Roberts, MD 

Overview

Practice Essentials

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.

Indications and contraindications

Indications

Indications for intestinal anastomosis can be broadly divided into two categories: restoration of bowel continuity following resection of diseased bowel and bypass of unresectable diseased bowel. Certain pediatric conditions may also require intestinal anastomosis.

Resection of diseased bowel is performed in the following settings:

  • Bowel gangrene due to vascular compromise caused by mesenteric vascular disease, prolonged intestinal obstruction, intussusceptions, or volvulus
  • Malignancy
  • Benign conditions (eg, intestinal polyps, intussusception, roundworm infestation with intestinal obstruction )
  • Infections (eg, tuberculosis complicated with stricture or perforation)
  • Traumatic perforations
  • Large perforations (traumatic) not amenable to primary closure
  • Radiation enteritis complicated with bleeding, stricture, or perforation
  • Inflammatory bowel disease, ulcerative colitis, or Crohn disease that is refractory to medical therapy or associated with complications (eg, bleeding, perforation, toxic megacolon, dysplasia/carcinoma)
  • Chronic constipation, idiopathic slow transit constipation, or Hirschsprung disease: Subtotal colectomy may be performed when the disease is refractory to medical therapy

Bypass of unresectable diseased bowel is performed in following settings:

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

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

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

Contraindications

Contraindications to intestinal anastomosis include conditions in which there is high risk of anastomotic leak, 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

Perioperative management

Perioperative management includes the following:

  • Preoperative fluid resuscitation
  • Preoperative antibiotic prophylaxis
  • Placement of nasogastric tube and indwelling urinary catheter
  • Venous thromboembolism prophylaxis

Operative techniques

Adequate exposure and access, gentle handling of the bowel, adequate hemostasis, approximation of well-vascularized bowel, absence of tension at anastomosis, good surgical technique, and avoidance of fecal contamination are tenets of good intestinal anastomosis.

The image below depicts a completed small-bowel anastomosis.

Completed small bowel anastomosis. Completed small bowel anastomosis.

Surgical techniques used in intestinal anastomosis include the following:

  • Incision and exposure
  • Bowel resection
  • Handsewn anastomosis (eg, bowel anastomosis, gastrojejunostomy, colorectal anastomosis, esophagogastric anastomosis)
  • Stapled anastomosis (eg, gastrojejunostomy, small-bowel anastomosis, colorectal anastomosis, cervical esophagogastric anastomosis)

Postoperative complications

Important complications following intestinal anastomosis include the following:

  • Anastomotic leak
  • Bleeding
  • Wound infection
  • Anastomotic stricture
  • Prolonged functional ileus, especially in children

Background

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.

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.

Indications

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

Contraindications

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)

Technical Considerations

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.[6]

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.

 

Periprocedural Care

Preprocedural Planning

Preoperative fluid resuscitation to optimize hydration status is imperative because patients who present in emergency settings are frequently dehydrated.

Preoperative antibiotic prophylaxis is a must to prevent infective complications in emergency settings, as well as in some elective settings when associated with a major surgical procedure.

A nasogastric tube and indwelling urinary catheter should be inserted to decompress the stomach and the urinary bladder, respectively. Decompression of the stomach reduces the risk of aspiration of gastric contents during induction of anesthesia.

Traditionally, mechanical bowel preparation has been given before elective colorectal procedures to prevent anastomotic complications.[7] However, there is evidence in the literature to suggest that mechanical bowel preparation does not have any beneficial effect on the complication rate; in fact, it might have a detrimental effect on healing by causing immune changes in colonic mucosa that interfere with the healing process.[8, 9]

Venous thromboembolism prophylaxis is a must to prevent deep vein thrombosis of lower limbs and possibly mesenteric venous thrombosis in high-risk patients (thrombophilic state).[10]

Equipment

Intestinal anastomosis is performed in an operating room, which should be equipped with the following:

  • Anesthetic equipment, overhead lights, and an operating table that is preferably power-controlled to ensure smooth and accurate positioning for various surgical procedures, electrodiathermy, and suctioning systems
  • Appropriate laparoscopic instruments and monitors (preferably high-definition) if laparoscopic resection and anastomosis are contemplated
  • Double-lumen endotracheal tube with single-lung ventilation is required for thoracotomy/thoracoscopic esophagectomy and anastomosis
  • All types of suture materials (absorbable/nonabsorbable, monofilament/multifilament) used for intestinal anastomosis
  • Stapling devices commonly used for intestinal anastomosis, such as a transverse anastomosis (TA) stapler, a gastrointestinal anastomosis (GIA) stapler, and a circular end-to-end anastomosis (EEA) stapler (if stapled intestinal anastomosis is planned)

Patient Preparation

Anesthesia

Intestinal anastomosis is performed with the patient under general anesthesia. A double-lumen endotracheal tube with single-lung ventilation is required for thoracotomy/thoracoscopic esophagectomy and anastomosis. Patients who are anesthetized for emergency surgery (eg, for intestinal obstruction or gangrene gut) are at greater risk for aspiration of gastric contents. The risk of aspiration can be reduced by emptying the stomach before induction and by using rapid-sequence induction technique.

Positioning

Patient positioning depends on the type of surgical procedure to be performed. Most abdominal operations are performed with the patient supine  and the arms abducted at right angles to the body or, sometimes, by the side of the body. Pelvic procedures are performed with the patient in the lithotomy position.

Care should be taken to avoid excessive flexion or abduction. Adequate padding of pressure points should be ensured to avoid neurologic damage and pressure injuries. Esophageal procedures (requiring thoracotomy) are performed with the patient in a lateral or semiprone position. Patient positioning also must be changed during the course of operation to facilitate performance of the surgical procedure.

 

Technique

Approach Considerations

Preoperative nasogastric aspiration is usually required. Similarly, urinary catheterization is necessary in critically ill patients, during emergency resections, or when infraumbilical incision is used to protect the urinary bladder from injury during laparotomy.

An exploratory laparotomy may be performed. If the disorder is diagnosed preoperatively, the pathology can be identified and the part of the intestine to be resected can be isolated and excised. Continuity is restored by performing the anastomosis.

Sometimes, the resection and anastomosis of the bowel could be components of another major surgical procedure, such as a Whipple procedure, gastrectomy, urinary diversion, or resection of a retroperitoneal tumor.

Controversies

Type of suture material

The ideal suture material is one that is easy to handle, ties without fraying, is easy to sterilize, elicits little or no inflammation, and maintains the strength of the anastomosis during the lag phase of healing. None of the currently available suture materials fulfills all of these criteria.

Absorbable suture materials that are commonly used for intestinal anastomosis include the following:

  • Polyglactin
  • Polyglycolic acid
  • Chromic catgut

The first two elicit less inflammation than catgut does.[11]

Silk is the most commonly used nonabsorbable suture, though it initiates an intense inflammatory reaction. Newer synthetic nonabsorbable sutures (eg, polypropylene) elicit less inflammatory reaction.

Generally, in two-layer anastomoses, absorbable sutures of polyglycolic acid or polyglactin are used, with an outer seromuscular stitch of silk. In one-layer anastomoses, a nonabsorbable suture such as silk is preferred.

Single-layer vs double-layer anastomosis

The intestinal anastomosis is traditionally performed in two layers. The shortcoming of the two-layer technique is that it is somewhat tedious and time-consuming to perform. Potential advantages of the single-layer technique are that it takes less time to perform and that it costs less, though safety may be a concern. However, randomized trials and meta-analyses comparing the two techniques of intestinal anastomosis did not find increases in the rate of anastomotic leakage, the incidence of perioperative complications, mortality, or the length of hospital stay with the single-layer technique.[12, 13, 14, 15]  

A report (N = 858) on the use of single-layer continuous horizontal mattress anastomosis (n = 369) instead of the conventional double-layer interrupted anastomosis (n = 489) in pediatric patients undergoing colonic anastomosis documented a reduced rate of dehiscence in emergency or elective settings.[16] Patients undergoing horizontal mattress anastomosis had fewer anastomotic complications, including peritonitis or abscess, anastomotic leakage, and anastomotic strictures; they also had shorter hospital stays. 

Continuous vs interrupted sutures

An intestinal anastomosis can be fashioned by using either simple (continuous) or interrupted sutures. A continuous suture is less time-consuming to place, and the suture line is more watertight with better hemostasis. However, the entire suture line is based on a single stitch.

Animal studies have shown that anastomotic blood flow and perianastomotic oxygen tension are low after a continuous suture, resulting in impaired healing and increased complication rates.[17]  However, prospective randomized trials have failed to show any difference in complication rates between the two techniques.[12] . 

Handsewn vs stapled anastomosis

The introduction of reliable disposable instruments has led to an increase in the use of stapling devices for intestinal anastomosis. A meta-analysis comparing stapled and handsewn anastomoses in colorectal surgery included nine studies involving 1233 patients (622 stapled and 611 handsewn); the authors did not find any significant difference in the incidence of anastomotic leakage between the two techniques.[18]

Another meta-analysis included 13 trials comparing handsewn with stapled colorectal anastomosis and found a high incidence of stricture and intraoperative problems in the stapled group.[19]  Animal studies have found that a stapled anastomosis heals by secondary intention, whereas a sutured anastomosis heals by primary intention; this may account for the high rate of stricture.

Another systematic review compared handsewn and stapled techniques of ileocolic anastomosis in six trials and 955 patients (357 stapled, 598 handsewn). The authors found a significantly lower leak rate in stapled anastomosis.[20]

Important advantages of the stapled technique are the shorter operating time and the greater ease of performing the procedure, especially in low pelvic anastomoses.

The use of an automatic suturing machine for intestinal anastomosis was reported by Mosafer Khoorjestan et al in an in-vitro setting.[21] The machine, which was designed and fabricated for this study, was equipped with a needle-driving system, a thread-control mechanism, and a linear mechanism (applicable to continuous suturing in intestinal anastomosis). The primary benefits of automatic suturing were the use of biocompatible suture and the capacity to carry out a uniform suturing pattern that was independent of the surgeon's skill, yielding greater strength than the hand-sutured anastomosis carried out by an experienced surgeon.

Inverting vs everting anastomosis

A 1966 comparison of inverted and everted techniques for anastomosis in experimental animals concluded that an inverted anastomosis had a weaker union than an everted anastomosis. The authors stated that the use of interrupted silk sutures used to evert the anastomosis was better than the conventional two-layer inverting technique.[22]

However, these early findings were contradicted by Goligher et al.[23]  In a randomized trial comparing these two techniques of colorectal anastomosis, the everted suture anastomosis group had a substantially higher rate of fecal fistula (43%) than the inverted suture anastomosis group (8%). Currently, inverted anastomosis is the most widely used technique worldwide.

Incision and Exposure

Adequate access is the key to ensuring successful intestinal anastomosis. A midline incision is commonly used for the majority of abdominal operations. The use of self-retaining retractors ensures adequate exposure. Exposure in pelvic operations can be improved by changing the position of the patient (Trendelenburg position) so as to displace small-bowel loops away from the pelvis. Packing the small bowel with wet sponges also improves exposure in pelvic procedures. A supraumbilical transverse incision is frequently used in younger children.

Bowel Resection

The portion of bowel to be resected should be adequately mobilized. Mobilization is rarely a problem with the small bowel, which can be easily brought to the surface. However, the large bowel (especially the retroperitoneal segments) should be adequately mobilized by dividing the lateral peritoneal reflection. Bowel mobilization, in addition to facilitating resection, ensures tension-free anastomosis.

After mobilization of the bowel, the next step is division of the mesentery. Principles to be followed in division of the mesentery include the following:

  • Transillumination to identify mesenteric blood vessels
  • Isolation of vessels by dividing surrounding fat
  • Division between clamps
  • Ligation with suitable sutures to prevent knot slippage

On-needle transfixation of large vascular pedicles with nonabsorbable sutures is a safer method. Bleeding or hematoma formation within the leaves of mesentery should be avoided, and preservation of vascular arcade to the bowel ends should be ensured so as to have satisfactory vascularity of the anastomosed bowel. Alternatively, the mesentery can be divided with an ultrasonic scalpel.

The next step is division of the bowel. This is done by applying a noncrushing clamp on the bowel end used for anastomosis and applying crushing clamps on the bowel to be resected so that the intraluminal contents of the resected bowel do not contaminate the peritoneal cavity. Clamps are applied from the antimesenteric end, and care should be taken to avoid crushing of the mesentery.

The bowel is divided with a knife close to the crushing clamp so as to preserve adequate bowel length distal to a noncrushing clamp for anastomosis. The direction of division is oblique to ensure an adequate lumen and to maintain a longer length of the mesenteric end as compared with the antimesenteric end. The specimen is removed with clamps in situ.

Care should be taken to avoid spillage of enteric contents during bowel division. Alternatively, bowel division can also done with a linear cutting (gastrointestinal anastomosis [GIA]) stapler, which divides and seals two cut ends simultaneously, thereby preventing fecal contamination.

Handsewn Anastomosis

Small-bowel anastomosis

This section describes a double-layer sutured end-to-end small-bowel enteroenterostomy. Two cut ends of the bowel are brought in close apposition. Stay sutures of 3-0 silk are placed between the serosa of the proximal and distal ends of the bowel approximately 5 mm from the cut end.

Interrupted seromuscular sutures (Lembert stitches) of 3-0 silk are placed between these stay sutures with a gap of approximately 3 mm between each two sutures. Lembert stitches should incorporate only the seromuscular layer; care must be taken not to incorporate the full thickness of the bowel wall. Sutures are tied sequentially, with care taken not to apply excessive tension so as to minimize the risk of cut-through of the seromuscular layer. This forms the posterior outer layer.

Next, a Connell stitch is made in both ends. The Connell stitch is achieved by passing the suture from the outside in, then inside out, on one end. The same step is repeated on the other end in the form of a continuous U-shape. The suture is tied so that the knot is outside. The posterior inner layer is completed by taking interrupted full-thickness stitches of 3-0 polyglactin, starting from the near end. The sutures are tied sequentially so that the knot lies inside the lumen.

The needle must be pulled through each edge separately. Trying to include both edges in one pass of the needle can prevent the surgeon from taking a full-thickness bite on both edges. It is necessary to include the submucosa carefully because this is the strongest layer of the bowel wall and gives strength to the anastomosis.

The anterior inner layer is completed in a similar fashion, starting from the far end. The pouting of mucosa is prevented by taking a small amount of mucosa and a large part of the seromuscular layer, which results in inversion of the mucosa.

The anterior outer seromuscular layer is completed by taking interrupted Lembert stitches (see the image below).

Completed small bowel anastomosis. Completed small bowel anastomosis.

Narrowing of the lumen by including too much of the bowel into this layer should be avoided. Patency of the lumen can be confirmed by palpation across the anastomosis with the tips of the thumb and the index finger. The mesenteric defect is closed with interrupted stitches of 3-0 silk. Care should be taken to avoid injuring mesenteric vessels so as to prevent ischemia of the anastomotic site.

Gastrojejunostomy

This section describes the technique of gastrojejunostomy following distal gastrectomy. The first step is to bring up the jejunal loop in an antecolic position (see the image below).

Jejunal loop being prepared for antecolic gastroje Jejunal loop being prepared for antecolic gastrojejunostomy.

Interrupted Lembert seromuscular stitches of 3-0 silk are placed between the antimesenteric end of the jejunum and the posterior gastric wall. This forms the posterior outer layer. After application of a noncrushing intestinal clamp across the jejunal loop, an incision is made in the jejunum with a knife approximately 5 mm lateral to the seromuscular stitches.

The size of the jejunal opening should be slightly smaller than the gastric opening because the small bowel tends to stretch while taking sutures. Two Babcock clamps are placed (one on each anterior wall) to expose the posterior gastric and jejunal walls.

The posterior inner layer is started by making a Connell stitch at the near end with 3-0 polyglactin. The suture is tied so that the knot lies outside the lumen, and the free end of the thread is kept long and held with a hemostat. After the lumen is entered from the outside in with the needle end of the suture, full-thickness continuous interlocking stitches are taken through both edges. The needle must be pulled through each edge separately to ensure a full-thickness bite on both edges. This forms the posterior inner layer.

Once the far end is reached, a Connell stitch is made, and the anterior inner layer is completed by taking continuous interlocking through-and-through stitches. A loop-on-mucosa suture technique is followed, in which the suture is taken from the inside out of the jejunal wall and outside in through the stomach wall, with the pull on the suture being within the lumen. This ensures good inversion of the mucosa (see the image below).

Third layer of gastrojejunostomy completed with co Third layer of gastrojejunostomy completed with continuous polyglactin suture. There is no pouting of mucosa.

Good inversion of the mucosa is also ensured by taking a small amount of mucosa and a large part of the seromuscular layer. Once half of the anterior inner layer is completed, clamps are released to ensure the absence of bleeding in the posterior layer. If bleeding points are identified, they are controlled by taking interrupted full-thickness stitches through both edges.

The anterior inner layer is completed by tying the free end of the thread on the near end. The double-layer anastomosis is completed with an anterior seromuscular layer of interrupted 3-0 silk sutures (see the image below).

Gastrojejunostomy completed using interrupted Lemb Gastrojejunostomy completed using interrupted Lembert silk sutures.

Colorectal anastomosis

Reconstruction after an anterior resection can be performed in either an end-to-end or a side-to-end fashion. A side-to-end technique (Baker anastomosis) is preferred when there is a size discrepancy between two bowel ends. This section describes the technique of end-to-end hand-sewn colorectal anastomosis following anterior resection.

Two bowel ends with right-angle clamps in situ are brought close by applying lateral seromuscular traction sutures of 3-0 silk. The anastomosis is performed in a single layer with 3-0 silk. Posterior interrupted full-thickness sutures are taken from the distal rectum to the proximal sigmoid colon. Sutures are not tied but are held long with a hemostat. This ensures accurate placement of full-thickness sutures.

After completion of the posterior layer, sutures are tied in order, starting from one corner. While one suture is being tied, the next suture should be held taut by an assistant to ensure that there is no abnormal gap between the two sutures. Next, full-thickness interrupted anterior-layer sutures are taken, following principles similar to those adopted for the posterior layer.

Sutures are then tied to complete the anastomosis. The integrity of the anastomosis can be checked by filling the pelvis with saline and instilling air through the anus to look for any air bubbles. Transanal anastomosis has also been described after total mesorectal excision (TME).[24, 25] Evaluation of the anastomosis with indocyanine green (ICG) fluorescence assess the vascularity of the bowel being anastomosed is now frequently practiced; if necessary, the transection line for anastomosis is changed so as to achieve a healthy anastomosis. This has become a common practice in laparoscopic or robotic colorectal surgery.[26, 27]

Esophagogastric anastomosis

The characteristic feature of the esophageal anatomy is the unusually fatty submucosa, which allows greater mobility of the overlying mucosa. In performing an esophageal anastomosis, care should be taken to ensure that every suture transfixes the mucosal edge, which can retract more than 1 cm from the cut esophageal margin. The esophagus also lacks a serosal layer, so that the soft and often tenuous muscle holds sutures poorly. This section describes the technique of two-layer end-to-side esophagogastric anastomosis using 3-0 silk.

The outer posterior layer uses interrupted stitches between the muscular layer of the esophagus and the seromuscular layer of the stomach. Initially, sutures are placed without being tied. During tying, care should be taken to draw the stomach towards the esophagus because the muscular layer of the esophagus holds sutures poorly. Corner ties are left long and held with a hemostat.

The posterior inner layer uses interrupted stitches left long without tying. The mucosa should be identified and included in each stitch to achieve mucosal apposition and avoid anastomotic leak. Sutures are then tied sequentially so that the knot lies inside the lumen. At this stage, the nasogastric tube is passed from the esophagus into the stomach and fixed by the anesthetist to the patient’s nose.

The anterior inner layer is completed in a similar fashion, with care taken to include mucosa. The sutures are tied so that the knot lies outside the lumen.

Anastomosis is completed by taking the anterior outer layer of interrupted stitches between the muscular layer of the esophagus and the seromuscular layer of the stomach.

A single-layer esophagogastric anastomosis also can be fashioned with interrupted silk sutures. Before the anastomosis is performed, the stomach can be hitched to the prevertebral fascia with interrupted silk sutures so that it does not slide down with peristalsis.

Stapled Anastomosis

Small-bowel anastomosis

A stapled small-bowel anastomosis can be performed in either an end-to-end (anatomic or functional) or a side-to-side fashion. True anatomic end-to-end small-bowel anastomosis is performed with a noncutting linear stapler. An important prerequisite for this type of anastomosis is that there should not be any disparity in size between the two bowel ends.

The first step is to triangulate the bowel ends by placing three traction sutures. The linear stapler is placed between two of the sutures and fired. The same process is repeated twice on the other two sides of the triangle by rotating the bowel. Any excess tissue remaining after the firing of the stapler is removed. This technique results in an everting anastomosis. Potential drawbacks of this technique are the possible anastomotic site stricture and ischemic damage secondary to an injury of mesenteric blood vessels when staples are applied close to the mesenteric end.

However, stapled small-bowel anastomosis is commonly performed in a functional end-to-end fashion by using a linear cutting stapler. In this technique, two cut ends of the bowel are placed side to side. The two forks of the stapling device are placed through open bowel ends or an enterotomy (made in the antimesenteric border if the bowel ends are stapled). Care should be taken to avoid inclusion of the mesentery between branches of the stapler.

The stapler is then fired to create lumen between two bowel segments by dividing the two bowel walls. The bowel ends or enterotomy can be closed by applying a linear stapler or using a hand-sewn technique.

Bleeding from stapled edges is better controlled by taking underrunning sutures. Care should be taken to avoid application of cautery to the stapled edge; doing so can result in transmission of electric current to the rest of the bowel, resulting in thermal damage.

In the case of benign duodenal neoplasms, minimally invasive tumor resection with robotic assistance and duodenojejunal anastomosis formation with an OrVil catheter is a newer treatment approach that appears promising.[28]

Gastrojejunostomy

This section describes the technique of stapled gastrojejunostomy following subtotal gastrectomy. Resection of the stomach is carried out with a linear cutter so that the cut end is excised and simultaneously stapled.

After completion of the gastrectomy, the jejunal loop is brought up in an antecolic or retrocolic fashion. Seromuscular interrupted stay sutures of 3-0 silk are placed between the posterior gastric wall close to the greater curvature and the jejunal wall to bring them in apposition. A small gastrotomy and enterotomy are made to facilitate the passage of a 55-mm linear cutting (GIA) stapler.

The two limbs of the GIA stapler are placed simultaneously into the stomach, with the cartridge fork of the linear cutter inside the stomach. Care should be taken not to include part of the small-bowel mesentery. The stapler is fired so that the common wall between the stomach and the jejunum is divided and the gastrojejunostomy created.

The nasogastric tube can be either placed in the stomach or advanced into the efferent jejunal loop if early enteral feeding is planned. The enterotomy and gastrotomy can be closed with an appropriately sized linear stapler or in two layers, with the inner continuous layer using 3-0 polyglactin and the outer interrupted layer using 3-0 silk.

Colorectal anastomosis

A stapled colorectal anastomosis following anterior or lower anterior resection for carcinoma of the rectum can be performed in either an end-to-end or an end-to-side fashion. This section describes the technique of an end-to-end double-stapled colorectal anastomosis.

After mobilization of the splenic flexure, proximal division of colon is performed at the junction of the sigmoid and descending colon. Bowel division can be performed by using a 55-mm linear transverse anastomosis (TA) stapler or cutting with a knife after applying a bowel clamp.

After complete mobilization of the rectum, a right-angle clamp is applied distal to the tumor, and the distal rectum is divided with a linear stapler (30-mm or 45-mm contour device or roticulator) applied distal to the right-angle clamp. An adequate distal mural margin (2 cm) is necessary to prevent recurrence. The distal rectal stump can be washed with saline or dilute povidone-iodine to destroy exfoliated tumor cells shed in the distal rectum before a clamp or stapler is applied.

After division of the distal rectum, the bowel ends are prepared for a double-stapled anastomosis using a circular stapler (31-mm or 33-mm end-to-end anastomosis [EEA] stapler). The proximal bowel is prepared by applying full-thickness purse-string stitches of 3-0 silk or polypropylene. The anvil head is placed in the proximal colon, and the purse-string suture is tied above the tying notch.

After gentle dilatation of the anus, the shaft of the circular EEA stapler is advanced through the anal canal under the guidance of the abdominal surgeon and placed close to the staple line with the trocar fully retracted inside. The trocar is then fully extended so as to pierce the tissue and advance through the rectal wall, either anterior or posterior to the staple line. The detachable head assembly is then reattached by sliding the anvil shaft over the trocar and pushing until the detachable head assembly snaps with the trocar into its fully seated position.

The ends of the circular stapler are closed, with care taken to confirm that there is no twist in the mesentery of the proximal colon. The stapler is tightened completely, fired, and then gently removed by rotating it counterclockwise for half a turn before removal. The presence of two intact donuts should be confirmed.

The integrity of the anastomosis should be checked by filling the pelvis with saline, instilling air in the distal rectum, and looking for air bubbles. If donuts are not complete, additional sutures should be made. In some cases, proximal diversion with proximal colostomy or ileostomy may be considered.

Cervical esophagogastric anastomosis

This section describes the technique of stapled cervical esophagogastric anastomosis popularized by Orringer.[29] After removal of the tumor-bearing segment of the esophagus and division of the proximal esophagus, the gastric tube is brought into the neck. A 1.5- to 2-cm-long anterior vertical gastrotomy is made for passage of stapler.

The site for the gastrotomy is selected by approximating the divided end of the esophagus against the anterior gastric wall. It should be low enough to facilitate subsequent placement of a 3-cm-long stapler cartridge.

The esophagus is aligned to the stomach by placing two stay sutures. The first suture is the full-thickness stitch through the anterior corner of the esophagus. The second is the full-thickness stitch through the upper end of the gastrotomy (inside out) to the posterior corner of the divided esophagus (outside in). A GIA stapler (30 mm) is inserted simultaneously into the stomach and esophagus while downward traction on the sutures is maintained, with the thicker staple-bearing portion of cartridge inside the esophagus.

Two stay sutures are placed between the anterior gastric wall and the adjacent esophagus on either side of the stapler to take tension off the anastomosis. The stapler is fired so that the common wall formed by the posterior esophageal wall and anterior gastric wall is divided, creating a large esophagogastric anastomosis.

A 16-French nasogastric tube is inserted by the anesthetist and advanced across the anastomosis into the intrathoracic stomach.

The esophagotomy and gastrotomy are closed with sutures in two layers (an inner continuous layer using 3-0 or 4-0 polyglactin and an outer interrupted layer using 3-0 silk).

Technique in Children

The bowel loop with the pathologic finding is isolated. Gentle bowel handling throughout the procedure is very important. Noncrushing intestinal clamps may be used for isolating the loop to be excised. The mesenteric vessels supplying the part to be excised are identified and divided after ligation with silk ligatures.

The intestinal loop is excised, and the cut edges are examined for bleeding and viability. If viability is doubtful, more bowel is excised. The adequacy of the lumen is ensured, and the anastomosis is performed with interrupted sutures in a single layer. The most commonly used suture material is polyglactin 910. Intraluminal staplers have been used for intestinal anastomosis and are said to reduce the operating time of most surgeons.[30]

With intestinal atresia, it is necessary to reduce the size of the proximal atretic end by excising the dilated end portion or performed a tapering enteroplasty to facilitate performance of the anastomosis. This is necessary to avoid the prolonged functional obstruction that may occur. (See the image below.)

Intestinal atresia with dilated proximal loop and Intestinal atresia with dilated proximal loop and narrow distal loop.

Sometimes, an end-to-back anastomosis may be necessary. The images below show the anastomosis in progress following resection for intestinal atresia.

Two ends of the bowel after excising the atretic e Two ends of the bowel after excising the atretic ends. Note the near equal lumen.
Posterior wall of anastomosis completed. Posterior wall of anastomosis completed.
Anastomosis completed with closure of mesentry def Anastomosis completed with closure of mesentry defect.

For multiple intestinal atresias present in a neonate, it may be necessary to perform multiple anastomoses as a single-stage procedure.

For meconium ileus, a chimney procedure (eg, Mikulicz procedure, Bishop-Koop procedure, or Santulli enterostomy) may be done.

Necrotizing enterocolitis may necessitate different procedures (eg, primary resection and anastomosis, resection and enterostomy, or relook surgery after a “clip-and-drop procedure”), depending upon the condition of the intestine and the extent of the disease.

Complications

Important complications following intestinal anastomosis include the following:

  • Anastomotic leakage
  • Bleeding
  • Wound infection
  • Anastomotic stricture
  • Prolonged functional ileus, especially in children

Anastomotic leakage

Anastomotic leakage is the most feared early complication of intestinal anastomosis. The healing of an intestinal anastomosis is broadly divided into three phases, as follows:

  • Inflammatory phase
  • Fibroplasia phase
  • Remodeling phase

During the inflammatory phase, the integrity of the anastomosis is dependent on mechanical strength provided by sutures. The inflammatory phase is followed by the fibroplasia phase around postoperative days 5-7; this phase is characterized by a switch from collagen degradation to collagen deposition, which gives strength to the anastomosis. Any systemic or local factor that causes delay in the transition from the inflammatory phase to the fibroplasia phase can result in poor healing and anastomotic leakage.

Systemic conditions that increase the risk of anastomotic leakage are anemia, diabetes mellitus, malnutrition with hypoalbuminemia, vitamin deficiencies, and steroid therapy. Local factors such as the presence of irradiated bowel, anastomosis involving disease-affected bowel, and inadequate blood flow are associated with poor healing and anastomotic leakage.

In a 2012 prospective study of 616 patients who underwent colorectal resection, anastomoses less than 10 cm from the anal verge, a Charlson Comorbidity Index of 3 or more, high ligation of the inferior mesenteric artery, male sex (possibly by reason of the narrower pelvis), and intraoperative complications or adverse events that were either surgical or anesthesia-related were found to be independent risk factors for anastomotic leakage after large-bowel surgery.[31]

Anastomotic leakage presenting on postoperative day 1 or 2 is invariably due to technical reasons. Anastomotic leakage secondary to interference in the normal healing mechanism usually presents around the end of postoperative week 1. Anastomotic leakage can present either as frank peritonitis when the leak is uncontrolled or as localized intra-abdominal collection/abscess if the leak is controlled.

An uncontrolled leak with diffuse peritonitis is associated with high morbidity and mortality and necessitates reexploration. During repeat laparotomy, a thorough lavage of the peritoneal cavity should be carried out. In most circumstances, it is better to dismantle the anastomosis and bring out the bowel loops as a stoma. A controlled leak presenting with a localized intra-abdominal abscess can be managed conservatively with percutaneous drainage of the abscess under imaging guidance and antibiotics.

In a study of 452 consecutive patients undergoing bowel resection with anastomosis, Erb et al found that abnormal vital signs were common after surgery and did not accurately predict the presence of anastomotic leaks.[32] In postoperative week 1, fever, tachycardia, tachypnea, hypotension, and leukocytosis occurred daily in approximately 70% of patients who did not have anastomotic leaks and in more than 90% of those who did. The positive predictive values for fever, hypotension, and tachypnea were 11%, 4%, and 4%, respectively.

Bleeding

Bleeding-related complications after intestinal anastomosis are common in patients with sepsis and deranged coagulopathy. Bleeding may manifest in the immediate postoperative period as hemorrhagic aspirate from the nasogastric tube, hematemesis, melena, or bleeding from an intra-abdominal drain.

Patients with bleeding should be aggressively managed with correction of coagulopathy (if present) and blood transfusion. If the bleeding results in hemodynamic instability with a significant decrease in hemoglobin, urgent reexploration should be performed. Intraoperative anastomotic site bleeding is characterized by blood in the intestinal lumen distal to the anastomosis. In such circumstances, the anterior layer of the sutures is opened and both layers are examined for evidence of any bleeding.

Once the bleeding site is identified, it can be controlled with hemostatic sutures. The decision to reanastomose or to convert into a stoma depends on the general condition of the patient. Conversion to a stoma is preferred in patients who are hemodynamically unstable.

Wound infection

Wound infection occurs when there is uncontrolled spillage of intestinal contents during anastomosis. It is managed by removing a few skin sutures and ensuring proper drainage of pus. Superficial surgical site infection does not require treatment with systemic antibiotics.

Anastomotic stricture

Anastomotic stricture is a late complication of intestinal anastomosis. The risk of anastomotic stricture is marginally increased after end-to-end anastomosis, especially when the anastomosis is performed with a stapled technique.

The most important risk factor for anastomotic stricture is a controlled anastomotic leak managed conservatively. This scenario is more common after cervical esophageal and colorectal anastomotic leaks. Anastomotic strictures occurring in these areas can be conservatively managed with endoscopic or colonoscopic dilatation. If this fails, surgical revision might be required.