Small bowel resection can be done during an open or laparoscopic procedure depending on the timing and indication for the surgery. For elective resections, bowel preparation with a low residue diet for several days preceding the date of surgery is generally undertaken. Mechanical bowel prep may be added but is not standard. Conditions requiring SBR are often emergent and therefore pre-op planning is limited to supportive care for the critically ill patient.

SBR involving the ileum or jejunum is straightforward as long as the bowel is adequate mobile. Duodenal resections are exponentially more complex due to the duodenum’s retroperitoneal position and proximity of the Ampulla of Vater, biliary tree, and pancreas. For this reason, duodenal resections will almost always require an extra-anatomic reconstruction, often specific to the pathology being addressed. Given the variety and complexity of procedures to treat duodenal pathology and the marked difference between resecting duodenum versus the more distal bowel, it is reasonable to reserve discussion of those procedures for their specific pathologies. For the sake of this article, SBR will reference resection limited to the ileum or jejunum.

The entire small bowel should be examined before resection. If the surgery is being performed open, the portion being resected should be eviscerated and placed on a towel to limit contamination from spillage.

Resections are planned based on the intended anastomosis: stapled or hand sewn. For a stapled anastomosis, defects are made through the mesentery close to the bowel wall, away from large vessels. Gastrointestinal anastomosis staplers (GIA), usually 60 mm linear cutting with a soft tissue load, are placed across the bowel through the defects. Staplers are then fired at a slightly oblique angle above and below the diseased segment, cutting and sealing the bowel in unison. The diseased, isolated segment of bowel is then freed from the mesentery using electrocautery, with identified vessels suture ligated with silk suture. Once removed, the sealed ends are most commonly reconnected using a side-to-side, functional end-to-end anastomosis. In this technique, the proximal and distal segments are aligned in parallel with the mesenteric borders adjacent to one another. It is important to inspect the base of the mesentery to ensure there is no abnormal rotation of the tissue. Sero-muscular sutures should be placed on the mesenteric side for support and to prevent migration. Small enterotomies are then made on the anti-mesenteric corner each segment. A common channel is then created by placing one limb of a GIA stapler into each lumen through these enterotomies. Firing the stapler then creates a common channel between the 2 segments. The common channel should be inspected to ensure there is no intraluminal bleeding at the staple line. Once hemostasis is confirmed, the enterotomies are then closed, usually by exclusion by firing another TA or GIA stapler across the top of the anastomosis. Edges should be checked to ensure the serosa is incorporated into the staple line on both sides. As the corners of the staple line have the higher risk of ischemia, Lembert stitches using absorbable suture should be placed in the corners, allowing the tissue to invert beneath the suture. Lastly, the mesenteric defect is closed with permanent or absorbable suture to prevent internal herniation. Care must be taken to avoid strangulating the edges of the mesentery, as main blood flow to the anastomosis will come from this tissue.

A 2-layer, hand-sewn anastomosis will increase operative time but remains the preferred method for many surgeons. First, appropriate mesenteric defects are created. The mesenteric tissue between the 2 defects is then clamped, and suture ligated. Two non-crushing clamps are placed across the bowel at each of the desired locations of transection, and the bowel is divided sharply. A 1-cm stump should be left beyond the end of the clamps for suturing. Anastomoses will typically be done in an end-to-end fashion, however side-to-side and end-to-side methods can also be employed. The later can be especially useful when a size discrepancy exists between the 2 segments, such as when 1 segment is more distended and edematous, or when making an ileocecal anastomosis.

With the diseased bowel segment now cut and removed, the cut ends of the small bowel are held aligned and stay sutures are placed in the corners. The clamps holding the bowel ends are rotated in opposition to one another to bring the posterior outer serosal layers together. A series of silk interrupted Lembert sutures are then placed through the seromuscular layers to conjoin the 2 segments. This is continued until the stay sutures are reached at each end. Next, absorbable sutures are placed in full-thickness bites to form the posterior inner layer along the same distance. The sutures should be placed so that the mucosa inverts and contacts the opposing mucosa throughout. With the posterior layer complete, absorbable Connel (U-shaped) stitches are placed in the corner, and the pattern is continued to close the anterior inner layer. Suturing of the inner layers can be safely done with either interrupted or continuous patterns. Continuous sutures have shown in animal models to cause decreased perianastomotic tissue oxygen tension when compared to interrupted sutures; however, limited human trials have not shown any significant difference in anastomotic leak rates when comparing the 2. Once that anterior inner layer is closed, silk Lembert stitches are placed in interrupted fashion across the anterior outer surface, completing the 2-layer anastomosis.

If a single layer is preferred, the same steps as above are performed, with the Lembert stitches being excluded. A small bowel anastomosis can be safely created with single or double layer closure, largely depending on surgeon preference. Single layer closures have been shown to be faster when compared to a double layer. A Cochrane review concluded the 2 styles were equivocal in safety; however, a meta-analysis of available randomized trials comparing the 2 was only moderate quality, and therefore, the clinical discretion of the surgeon is always warranted. A single-layered closure is often preferred in patients with inherently narrow bowel lumens, such as neonates. A double-layer closure may cause a too-high risk of obstruction if the lumen is small. Overall, it is difficult to compare the 2 techniques on a broad scale, due to heterogeneity in all the factors that may affect the overall outcome. These factors include suture type, surgeon experience, patient factors such as disease being treated, and other comorbidities.

SBR that is done for mass or neoplasm will generally require oncologic margins of 8 to 10 cm along with associated mesentery and lymphatic tissue; whereas, benign processes only require limited resection with sparing of mesentery to preserve blood flow. If an oncologic resection is required, the primary vessel supplying the segment must be traced back to the mesenteric root and divided at its base. The adjacent mesentery is then fully resected in a wedge shape extending from the small bowel back to the origin of the vessel. This should allow for adequate lymph node harvest.

Under most circumstances surrounding a SBR, the surgeon will plan to return the small bowel to normal anatomic continuity. Numerous situations exist where this may not be preferred. The surgeon may opt for an extra-anatomic reconstruction if to bypass or exclude a segment of diseased or non-functional bowel that cannot otherwise be removed. With a distal ileum resection, creating of an ileocolonic anastomosis may be risky if there is a large size discrepancy between the two ends and/or a hostile environment from inflammation or infection. In this case, an end-ileostomy will be the safest option for the patient.

Creation of an ileostomy starts with choosing a site for the ostomy, away from other incision sites and above the belt line. When possible, this site should be chosen and marked pre-operatively with the patient awake and sitting upright. A circular segment of skin is excised at the chosen spot, and sharp dissection is used to create a passage through the subcutaneous tissue to the rectus sheath. The rectus sheath is incised, and the muscle is bluntly dissected down to the level of the peritoneum, which is entered sharply. With the distal ileum adequately mobilized, it is grasped with a Babcock and gently delivered through the stoma, along with its supporting mesentery. Care must be taken to keep the terminal ileum is its correct orientation. Once the ileum is through the stoma, the main abdominal incision should be closed and covered before opening the bowel. The stapled/sutured edge of the ileum should then be excised to produce a fresh bleeding edge. Absorbable sutures should be placed between the seromuscular layer of the bowel and the subcutaneous tissue in each quadrant to orient the ileostomy. Once secured, interrupted sutures can then be placed circumferentially, taking full-thickness bites of the bowel and securing it to the dermis. When tightened and tied, these should help to avert the end of the ostomy. Once complete, the ostomy should be checked for patency before application of a stoma appliance.

Superficial wound infections are common in contaminated cases. Allowing the wound to close by secondary intent can reduce the risk of soft tissue infection, abscess, and potential wound dehiscence.[5][6][7]

Anastomotic breakdown or leak is the most feared common complication after SBR with incidence varying from 1% to 24% based on numerous factors. Risk can be reduced by focusing on operative technique to ensure adequate blood supply with minimal tension. This must be combined with appropriate preoperative and postoperative supportive care to mitigate the effects of systemic patient disease and prevent protein-calorie malnutrition.

Unlike high-risk colonic anastomoses that can be protected with the proximal diversion of the fecal stream, diversion is not an option in SBR. Proximal diversion of anything proximal to the terminal ileum would impair the guts absorptive function. Proximal decompression with a nasogastric or gastric tube can help alleviate early stress on the healing anastomosis. The anastomotic breakdown will inherently allow enteric contents to permeate into the peritoneal cavity, causing abscesses, peritonitis, and sepsis, and often progress to abdominal wound dehiscence.

Fistulization is a common subacute complication of anastomotic breakdown after SBR. Enterocutaneous fistulas are both a common sequelae of anastomotic leaks, as well as a common reason for additional SBR if they are persistent. Enteroenteric and enterocolonic fistulae are not uncommon findings in a hostile abdomen of a malnourished or hemodynamically impaired patient. These are likely under-recognized due to the lack of external clinical signs and can contribute to malabsorption by allowing enteric contents to bypass a variable portion of the small bowel’s absorptive surface.

SBR, as with any intraabdominal surgery, can contribute to adhesions which increase future risk for obstruction.[8]

Massive SBR can lead to short bowel syndrome (SBS), a condition that is characterized by malnutrition and malabsorption secondary to loss of functional small bowel and more rapid intestinal transit. In addition to weight loss and protein-calorie malnutrition, patients suffer from diarrhea, steatorrhea, electrolyte abnormalities, and deficiencies in fat-soluble vitamins. This primarily occurs in patients that have suffered a very-long segment SBR or multiple sequential resections. SBS is highly morbid, with up to 1 in 3 patients perishing within the same hospitalization as a diagnosis. An additional 1 in 3 will die within the first year after diagnosis from malnutrition coupled with the inherent medical comorbidities attributable to treatment of the disease. [2]The goals of treatment for SBS are not just for a patient to be alive and well, but to maintain adequate nutrition with enteral feeds only. Patients who are forced to rely on prolonged parenteral nutrition will be subjected to high monetary cost, lifestyle limitations, as well as medical issues such as liver disease and increased risk for complications from chronic central venous catheters.

While the bowel’s absorptive capacity with improve with healing, small bowel remnant length is the most important prognostic factor for patients with SBS. Most adults have between 600 and 800 cm of the small intestine, and small bowel absorptive function is generally not impaired until greater than half of the bowel is gone. In adults, patients with greater than 180 cm of remaining small bowel will likely have enough absorptive surface to avoid long-term parenteral nutrition. Likewise, an adult with less than 60 cm of the small bowel will likely be dependent on parenteral nutrition indefinitely. The overall clinical severity is also affected by other factors affecting the absorptive capacity of the small bowel. Presence of the ileocecal valve and terminal ileum is a strong, positive, prognostic factor for weaning off parenteral nutrition. The underlying disease state necessitating resection may also impair the function of the remaining bowel. For example, improvement in function of chronically inflamed or irradiated bowel may plateau quickly, leaving a patient with SBS despite a relatively long segment.

Along with necrotizing enterocolitis in premature infants, congenital abnormalities such as volvulus or malrotation pose the highest risk of acquiring SBS in neonatal populations. Children with greater than 60 cm of bowel can usually be sustained with enteral nutrition alone. However, the prognosis for survival and adequate enteral nutrition is not accurately predicted based on overall bowel length due to variations in total bowel length based on gestation age. Overall survival for a child with SBS is around 70%. There tends to be marked increases in risk of death and as parenteral dependence as the percentage of predictive bowel length for gestational age approaches 10%, showing the amazing ability for the survival even in the face of a near-total loss of small bowel.

The goals of SBS management start with preventing weight loss and micronutrient deficiency while treating the underlying illness care to prevent the loss of any additional small bowel. Patients are typically in a critically ill, catabolic state at the time of diagnosis. Parenteral nutrition, therefore, is a mainstay of early SBS management to limit malnutrition. Early return to enteral feeds once ileus has resolved is advised, even if a diagnosis of SBS is expected. Enteral feeding is thought to stimulate intestinal adaptation by both directly stimulating enterocytes and by inducing endocrine and paracrine effects signaling for hypertrophy of the remaining small bowel mucosa. Drugs such as loperamide, diphenoxylate and atropine, and opiates will slow gut function, increasing the potential absorptive time of enteral feeds. Reducing gastrointestinal secretion and controlling diarrhea are also important goals for maximizing absorption.

Surgical options to treat small bowel syndrome are used sparingly in the adult population and reserved for patients unable to sustain with enteral feeds. Children are more likely to be surgical candidates, but they are also more likely to be able to thrive with enteral feeds. Regardless, numerous surgical options exist to either lengthen the small bowel or improve function.

Approximately 50% of patients with SBS will require additional intraabdominal surgery at some point after diagnosis for various intestinal problems. With any surgery on a patient with SBS, preserving the remaining small bowel should be the main concern of a surgeon.

More common in children, strictures can cause pseudo-obstruction, leading to bowel dilatation and bacterial overgrowth. These should be treated with stricturoplasty or resection of the redundant bowel. If a patient has dilated bowel (at least 3 to 4 cm) a STEP (serial transverse enteroplasty procedure) procedure can be effective in lengthening small bowel. Increases of up to 55 cm of intestinal length have been reported. The Bianchi procedure is another option for lengthening that has largely been replaced by the STEP. Patients with rapid transit can benefit from reversing of 10 to 15 cm segments of bowel. Short segment colonic interposition grafts have also been attempted with anecdotal reports of improvement.

Small bowel resection is done for many reasons. The surgery is usually performed by a general surgeon. However, the workup of patients with small bowel pathology usually involves an interprofessional team that includes a radiologist, pathologist, surgeon, gastroenterologist, the primary care provider, and nurse practitioner. Patients should be educated on the potential complications of surgery such as bowel leaks, strictures, deep vein thrombosis, abscess, and wound infections. Prior to surgery the patient should be informed about the need for bowel preparation.