Small bowel obstruction

Last reviewed: 23 Aug 2023

Last updated: 10 Aug 2021

Small bowel obstruction is a mechanical disruption in the patency of the gastrointestinal tract.

it is a medical emergency that requires early diagnosis and intervention.

It typically presents with the combined symptoms of abdominal pain, bloating, vomiting, and failure to pass flatus or stool per rectum.

Diagnosis is generally based upon clinical and radiographic features.

Treatment involves a combination of nasogastric decompression and intravenous fluids. Surgery may be required, so the diagnosis requires urgent surgical assessment.

Patients who are treated in a timely manner have a very good prognosis. If untreated, it is often fatal.

Definition

Small bowel obstruction (SBO) is a mechanical disruption in the patency of the gastrointestinal tract, resulting in a combination of emesis (that may be bilious), absolute constipation, and abdominal pain.

History and exam

Key diagnostic factors

constipation/failure to pass flatus or stool
abdominal pain
vomiting
abdominal distention
abdominal tenderness
peritonitis
palpable abdominal mass
palpable rectal mass

More key diagnostic factors

Other diagnostic factors

nausea
fever
tachycardia
severe lethargy
hypotension
diarrhea
groin swelling

Other diagnostic factors

Risk factors

previous abdominal surgery
malrotation
Crohn disease
hernia
appendicitis
intestinal malignancy
intussusception
volvulus
intestinal atresia
foreign body ingestion

More risk factors

Diagnostic investigations

1st investigations to order

abdominal CT scan
CBC
BUN
electrolyte panel

More 1st investigations to order

Investigations to consider

abdominal x-rays
water-soluble contrast study
laparotomy
laparoscopy
abdominal ultrasound
abdominal MRI

More investigations to consider

Treatment algorithm

ACUTE

complete or complicated or strangulated SBO: surgical candidate

complete or complicated or strangulated SBO: surgery contraindicated

partial SBO

Contributors

Authors

John T. Jenkins, MD

Consultant Colorectal Surgeon

Department of Coloproctology

St. Mark's Hospital

London

Disclosures

JTJ declares that he has no competing interests.

Edward T. Pring, BSc(Hons), MBChB, MRCS

Surgical Registrar and Clinical Research Fellow

St. Mark's Hospital

London

Disclosures

ETP declares that he has no competing interests.

George Malietzis, MBBS, MSc, MRCS

Honorary Clinical Lecturer

Department of Surgery and Cancer

Imperial College

London

Disclosures

GM declares that he has no competing interests.

Acknowledgements

Dr John T. Jenkins, Dr Edward T. Pring, and Dr George Malietzis would like to gratefully acknowledge Dr Frances J. McNicol and Dr David J. Hackam, previous contributors to this topic.

Disclosures

FJM and DJH declare that they have no competing interests.

Peer reviewers

Steven D. Wexner, MD, FACS, FRCS, FRCS (Ed)

Chief Academic Officer

Emeritus Chief of Staff (1997-2007)

Chairman Department of Colorectal Surgery

Professor of Surgery Ohio State University

Affiliate Professor Department of Surgery

Division of General Surgery

University of South Florida College of Medicine

Cleveland Clinic Florida

Disclosures

SDW declares that he has no competing interests.

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Small bowel obstruction

Summary

Definition

History and exam

Key diagnostic factors

Other diagnostic factors

Risk factors

Diagnostic investigations

1st investigations to order

Investigations to consider

Treatment algorithm

complete or complicated or strangulated SBO: surgical candidate

complete or complicated or strangulated SBO: surgery contraindicated

partial SBO

Contributors

Authors

John T. Jenkins, MD

Disclosures

Edward T. Pring, BSc(Hons), MBChB, MRCS

Disclosures

George Malietzis, MBBS, MSc, MRCS

Disclosures

Acknowledgements

Disclosures

Peer reviewers

Steven D. Wexner, MD, FACS, FRCS, FRCS (Ed)

Disclosures

Differentials

Guidelines

Patient leaflets

Videos

Log in or subscribe to access all of BMJ Best Practice

Log in or subscribe to access all of BMJ Best Practice

Log in to access all of BMJ Best Practice