Small Bowel Resection

Clatterbuck B, Moore L. Small Bowel Resection. [Updated 2023 Apr 17]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2025 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK507896/

Executive Summary

Small Bowel Resection (SBR) is a frequently performed procedure in general surgery to remove diseased or damaged segments of the small intestine. While the considerable length of the small bowel often permits resection without significantly impairing gastrointestinal function, the procedure carries notable risks and requires nuanced surgical techniques tailored to the specific pathology and anatomical location.

Key indications for SBR include obstruction, malignancy, perforation, ischemic necrosis, and complications of inflammatory bowel disease (IBD). Surgical approaches vary significantly; resections of the jejunum and ileum are generally straightforward, whereas duodenal resections are exceptionally complex due to the duodenum's retroperitoneal position and proximity to the pancreas and biliary tree. Anastomosis, the rejoining of the bowel, can be performed using stapled or hand-sewn techniques, with the choice often depending on surgeon preference and clinical context.

The most feared complication is anastomotic breakdown or leak, with an incidence rate ranging from 1% to 24%, which can lead to peritonitis, sepsis, and fistula formation. The most clinically significant long-term consequence of extensive SBR is Short Bowel Syndrome (SBS), a severe malabsorptive state characterized by malnutrition, diarrhea, and electrolyte imbalances. The prognosis for SBS is highly dependent on the length of the remaining small bowel; adults with less than 60 cm of remnant bowel are likely to require indefinite parenteral nutrition. Management of SBS is complex, focusing on nutritional support and, in select cases, surgical procedures to lengthen the bowel. Effective patient outcomes hinge on a collaborative, interprofessional healthcare team approach encompassing surgical, medical, and nutritional care.

1. Foundational Concepts of Small Bowel Resection

1.1. Definition and Scope

Small Bowel Resection (SBR) is a surgical procedure to remove a portion of the small intestine. It is a common procedure in general surgery, essential for managing a wide array of pathologies. Due to the significant length of the small bowel, resection can often be performed without critical compromise to the overall function of the gastrointestinal (GI) system. The procedure's success relies on a thorough understanding of small bowel anatomy, safe resection techniques, and management of potential complications.

1.2. Relevant Anatomy and Physiology

The small bowel is composed of three distinct segments: the duodenum, jejunum, and ileum. Surgically, the bowel wall is considered to have three main layers: the inner mucosa, the middle muscularis, and the outer serosa. The serosa provides the primary strength layer for holding sutures in an anastomosis.

Segment	Approximate Length	Key Anatomical & Physiological Features
Duodenum	25-30 cm	Blood Supply: Dual supply from the celiac axis and superior mesenteric artery (SMA).  Location: Mostly retroperitoneal, making surgical intervention uniquely challenging, especially near the second portion which contains the ampulla of Vater.  Function: Primary site for iron absorption.
Jejunum	100 cm	Characteristics: Characterized by circular muscular folds and long vasa recta. Blood Supply: 5-6 jejunal branches from the SMA. Function: The primary site for the absorption of most nutrients, water, and salt.
Ileum	150 cm	Characteristics: Characterized by short vasa recta. Blood Supply: 6-8 ileal branches from the SMA. The terminal ileum is supplied by the ileocolic artery. Function: Absorbs Vitamin B12, bile acids, and folate.

The blood supply to the jejunum and ileum originates from the Superior Mesenteric Artery (SMA), forming a "highly redundant arcade of vessels" within the mesentery. In a healthy individual, there are no watershed areas within the small bowel's vasculature.

2. Clinical Indications and Contraindications

2.1. Primary Indications for SBR

SBR is indicated for a variety of conditions where a segment of the small bowel is irreversibly damaged or diseased. While the general principles of the procedure are consistent, the underlying pathology often requires specific modifications to the surgical technique.

• Obstruction: Performed when obstruction is not correctable by adhesiolysis.

• Malignancy: Suspected malignancies typically require wide resection with 8-10 cm margins.

• Non-Traumatic Perforation: May be preferred over simple repair to allow for a definitive tissue diagnosis by a pathologist.

• Traumatic Perforation: Resection is required for defects that encompass more than 50% of the bowel loop's circumference.

• Ischemic Necrosis: Often progressive, potentially requiring multiple resections over several days and carrying high morbidity.

• Inflammatory Bowel Disease (IBD): Typically a last resort for strictures that are not amendable to stricturoplasty or conservative management.

• Enterocutaneous Fistula: When conservative measures for closure fail.

• Necrotizing Enterocolitis with Perforation: A common indication in neonatal populations.

• Symptomatic Meckel Diverticulum: Or other forms of diverticular disease.

2.2. Contraindications

There are no absolute contraindications applicable to the general population, as SBR is usually performed only when no other therapeutic options are available. However, active Inflammatory Bowel Disease (IBD) is considered a relative contraindication because the presence of local inflammation significantly increases the risk of anastomotic leak.

3. Surgical Techniques and Procedures

3.1. Preoperative Preparation

Preparation varies based on the urgency of the procedure.

• Elective Resections: May involve a low residue diet for several days pre-surgery. Mechanical bowel prep is not standard.

• Emergent Resections: Preoperative planning is often limited to supportive care for the critically ill patient.

• General Strategies: To minimize complications, recommended preparation includes optimizing the patient's nutritional status, weaning immunosuppressive agents, and draining any abdominopelvic abscesses.

3.2. Resection and Anastomosis Techniques

The surgical technique for SBR differs significantly based on the anatomical segment involved. Resections of the mobile jejunum and ileum are straightforward, while duodenal resections are "exponentially more complex" due to their retroperitoneal location and proximity to critical structures, often requiring specialized extra-anatomic reconstructions like a pancreaticoduodenectomy (Whipple procedure).

Anastomosis (Reconnection) Techniques:

Technique	Description	Key Steps & Considerations
Stapled Anastomosis	A common method using linear cutting staplers to create a side-to-side, functional end-to-end connection.	1. The bowel is divided and sealed with a GIA stapler. 2. The diseased segment is removed from the mesentery.  3. Proximal and distal segments are aligned, and a common channel is created by firing a GIA stapler through small enterotomies.  4. The enterotomies are closed with another stapler. 5. The mesenteric defect is closed to prevent internal herniation.
Hand-Sewn Anastomosis	A traditional method involving suturing the bowel ends together, typically in two layers. It increases operative time but remains a preferred method for many surgeons.	Two-Layer Technique: 1. An outer layer of interrupted silk Lembert sutures is placed through the seromuscular layers.  2. An inner layer of absorbable sutures is placed in full-thickness bites to invert the mucosa. Single-Layer Technique:  Faster than the two-layer method and often preferred in patients with narrow bowel lumens, such as neonates. A Cochrane review found the two styles equivocal in safety.
Oncologic Resection	Performed for malignancies to ensure adequate removal of cancerous tissue and associated lymph nodes.	Requires wide margins of 8-10 cm of healthy bowel.  The primary blood vessel supplying the segment is traced to the mesenteric root and divided at its base. The adjacent mesentery is resected in a wedge shape to allow for adequate lymph node harvesting.

3.3. Creation of an End-Ileostomy

In situations where an anastomosis is deemed too risky (e.g., due to hostile inflammation, infection, or a large size discrepancy between bowel ends), an end-ileostomy may be created. This involves bringing the end of the ileum through the abdominal wall to create a stoma for waste diversion. The site should be marked pre-operatively with the patient sitting upright to ensure proper placement away from the beltline and other incisions.

4. Complications and Clinical Significance

4.1. Postoperative Complications

SBR carries a risk of several significant complications.

Complication	Description	Incidence / Notes
Anastomotic Leak	Breakdown of the surgical connection, allowing enteric contents into the peritoneal cavity. This is the "most feared common complication."	Incidence varies widely from 1% to 24%, based on patient and procedural factors. Leads to abscess, peritonitis, and sepsis.
Fistulization	The formation of an abnormal connection between the bowel and another surface (e.g., skin, another bowel loop). Can be a sequela of an anastomotic leak.	Can lead to malabsorption by allowing enteric contents to bypass absorptive surfaces.
Adhesions	Scar tissue formation following intra-abdominal surgery, which increases the future risk of bowel obstruction.	A common long-term consequence of any intra-abdominal procedure.
Wound Infections	Common in contaminated cases. Can lead to soft tissue infection, abscess, and wound dehiscence.	-
Vitamin Deficiency	Specifically fat-soluble vitamins, due to rapid intestinal transit time which reduces the time available for emulsification and absorption.	This is a component of malabsorption seen after SBR.

4.2. Short Bowel Syndrome (SBS)

Massive SBR can lead to Short Bowel Syndrome (SBS), a severe condition of malabsorption and malnutrition.

• Pathophysiology: Caused by the loss of a significant length of functional small bowel, leading to rapid intestinal transit and an insufficient surface area for nutrient and fluid absorption.

• Symptoms: Include weight loss, protein-calorie malnutrition, diarrhea, steatorrhea, electrolyte abnormalities, and deficiencies in fat-soluble vitamins.

• Prognosis and Morbidity: SBS is highly morbid. Approximately one in three patients die during the initial hospitalization, and another one in three die within the first year. The single most important prognostic factor is the length of the remaining small bowel. The presence of the terminal ileum and the ileocecal valve is a strong positive prognostic factor.

Prognostic Bowel Length in Adults:

Remnant Bowel Length	Likely Outcome
> 180 cm	Likely to have enough absorptive surface to avoid long-term parenteral nutrition.
< 60 cm	Likely to be dependent on parenteral nutrition indefinitely.

4.3. Management of Short Bowel Syndrome

The primary goals are to prevent weight loss and micronutrient deficiencies.

• Nutritional Support: Parenteral nutrition is a mainstay in early management. However, an early return to enteral feeding is advised, as it stimulates intestinal adaptation and hypertrophy of the remaining bowel.

• Pharmacological Treatment: Medications like loperamide and opiates are used to slow gut transit, thereby increasing potential absorptive time.

• Surgical Options: Used sparingly in adults and reserved for patients who cannot be sustained on enteral feeds. Procedures aim to lengthen the small bowel (e.g., Serial Transverse Enteroplasty Procedure - STEP) or improve its function. Preserving every centimeter of the remaining small bowel is the primary concern in any subsequent surgery.