What are the causes and symptoms of small bowel obstruction (SBO)?

Medical Advisory BoardAll articles are reviewed for accuracy by our Medical Advisory Board
Article Review Status
Submitted
Under Review
Approved

Last updated: March 1, 2025 • View editorial policy

From the Guidelines

Small bowel obstruction (SBO) is a serious condition where the small intestine is partially or completely blocked, and its causes include adhesions, hernias, tumors, and inflammatory bowel disease, with symptoms such as cramping abdominal pain, nausea, vomiting, abdominal distension, and constipation, as reported in the most recent study by 1.

Causes of Small Bowel Obstruction

The causes of SBO can be categorized into several main groups, including:

  • Adhesions, which are the most common cause, accounting for approximately 55-75% of cases, as stated in 2
  • Hernias, which account for a significant proportion of cases, as mentioned in 2
  • Tumors, which can cause obstruction by compressing or invading the small intestine, as reported in 2
  • Inflammatory bowel disease, which can cause narrowing or obstruction of the small intestine, as stated in 2 ### Symptoms of Small Bowel Obstruction The symptoms of SBO can vary depending on the severity and location of the obstruction, but common symptoms include:
  • Cramping abdominal pain, which can be severe and debilitating, as reported in 1
  • Nausea and vomiting, which can lead to dehydration and electrolyte imbalances, as stated in 1
  • Abdominal distension, which can be caused by the accumulation of gas and fluid in the intestine, as mentioned in 1
  • Constipation, which can be caused by the obstruction of the intestine, as reported in 1 ### Diagnosis of Small Bowel Obstruction The diagnosis of SBO typically involves a combination of physical examination, laboratory tests, and imaging studies, including:
  • Abdominal X-rays, which can show dilated bowel loops and air-fluid levels, as stated in 3
  • CT scans, which can provide detailed images of the obstruction site and potential complications, as reported in 3
  • Physical examination, which can reveal signs of abdominal tenderness, guarding, and rebound tenderness, as mentioned in 1 ### Management of Small Bowel Obstruction The management of SBO depends on the severity and location of the obstruction, as well as the presence of any complications, and may include:
  • Conservative management, which involves bowel rest, nasogastric tube decompression, and IV fluids, as reported in 1
  • Surgical intervention, which may be necessary for complete obstructions, strangulation, or peritonitis, as stated in 4
  • Prophylactic antibiotics, which may be administered to prevent infection, as mentioned in 4

From the Research

Causes of Small Bowel Obstruction (SBO)

  • Adhesions are the most common cause of SBO in adults 5
  • Other causes include internal hernia, incarcerated incisional hernia, and inflammatory bowel disease 6
  • Malignant causes can also lead to SBO, but are often excluded from certain studies 6
  • Intra-abdominal adhesions are responsible for approximately 75% of patients admitted with SBO 7

Symptoms of Small Bowel Obstruction (SBO)

  • Abdominal distension, abnormal bowel sounds, and prior abdominal surgery are common findings 5
  • Signs of strangulation include fever, hypotension, diffuse abdominal pain, and peritonitis 5
  • Patients may also experience constipation, vomiting, and significant distension 5, 8

Diagnosis of Small Bowel Obstruction (SBO)

  • Imaging is typically required for diagnosis, with computed tomography (CT) and ultrasound being reliable methods 5, 9
  • Plain radiographs may be ordered, but cannot exclude the diagnosis 5
  • Abdominal CT and serum urea and electrolytes are considered essential initial investigations by most consultants 9

Management of Small Bowel Obstruction (SBO)

  • Intravenous fluid resuscitation, analgesia, and determining the need for operative vs. nonoperative therapy are important aspects of management 5
  • Nasogastric tube is useful for patients with significant distension and vomiting 5
  • Surgery is needed for strangulation and those that fail nonoperative therapy 5, 8
  • Laparoscopic approach may be considered for patients with a single obstructing band, but conversion to an open procedure should be done if necessary 7, 6

References

Guideline

bowel obstruction: a narrative review for all physicians.

World Journal of Emergency Surgery, 2019

Guideline

acr appropriateness criteria® suspected small-bowel obstruction.

Journal of the American College of Radiology, 2020

Research

Laparoscopic management as the initial treatment of acute small bowel obstruction.

JSLS : Journal of the Society of Laparoendoscopic Surgeons, 2006

Research

Adhesive Small Bowel Obstruction and the six w's: Who, How, Why, When, What, and Where to diagnose and operate?

Scandinavian journal of surgery : SJS : official organ for the Finnish Surgical Society and the Scandinavian Surgical Society, 2021

Research

Early operation or conservative management of patients with small bowel obstruction?

The European journal of surgery = Acta chirurgica, 2002

Research

Current management of small bowel obstruction in the UK: results from the National Audit of Small Bowel Obstruction clinical practice survey.

Colorectal disease : the official journal of the Association of Coloproctology of Great Britain and Ireland, 2018

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.