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Small bowel obstruction

Last reviewed: 10 Nov 2023
Last updated: 10 Aug 2021



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


complete or complicated or strangulated SBO: surgical candidate

complete or complicated or strangulated SBO: surgery contraindicated

partial SBO



John T. Jenkins, MD

Consultant Colorectal Surgeon

Department of Coloproctology

St. Mark's Hospital




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




ETP declares that he has no competing interests.

George Malietzis, MBBS, MSc, MRCS

Honorary Clinical Lecturer

Department of Surgery and Cancer

Imperial College




GM declares that he has no competing interests.


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.


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



SDW declares that he has no competing interests.

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