Last reviewed: June 2020
Last updated: July  2020



History and exam

Key diagnostic factors

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

Other diagnostic factors

  • pyrexia
  • nausea (with or without vomiting)
  • tachycardia
  • groin swelling

Risk factors

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

Diagnostic investigations

1st investigations to order

  • computed tomography 
  • water-soluble contrast study
  • arterial blood gases (including lactate)
  • full blood count
  • electrolytes 
  • C-reactive protein
  • urea/creatinine ratio
  • serum lipase or amylase
  • glucose
  • clotting, group and save, or cross-match
Full details

Investigations to consider

  • urine or serum beta–human chorionic gonadotrophin (HCG)
  • urinalysis
  • ECG
  • magnetic resonance imaging
Full details

Treatment algorithm


Expert advisersVIEW ALL

General and Colorectal Surgeon

Queen’s Medical Centre




JA is Clinical Lead for General Surgery, Getting It Right First Time.


JA is trustee and council member of the Royal College of Surgeons of England.

Consultant Colorectal Surgeon

Royal Victoria Infirmary




NR declares she has no competing interests.

BMJ Best Practice would like to gratefully acknowledge the previous team of expert contributors, whose work is retained in parts of the content:

John T. Jenkins MD

Consultant Colorectal Surgeon

Department of Coloproctology

St. Mark's Hospital 



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



Disclosures: ETP declares that he has no competing interests.


George Malietzis


Honorary Clinical Lecturer

Department of Surgery and Cancer

Imperial College London


Disclosures: GM declares that he has no competing interests.

Peer reviewersVIEW ALL

Consultant Colorectal Surgeon

Western Sussex Hospitals NHS Foundation Trust


West Sussex



Section Editor, BMJ Best Practice


EQ declares that she has no competing interests.

Lead Section Editor, BMJ Best Practice


TAO declares that she has no competing interests.

Head of Editorial, BMJ Best Practice


AE declares that she has no competing interests.

Comorbidities Editor, BMJ Best Practice


JC declares that she has no competing interests.

Drug Editor, BMJ Best Practice


AM declares that he has no competing interests.

Lead Section Editor


SM works as a freelance medical journalist and editor, video editorial director and presenter, and communications trainer. In this capacity, she has been paid, and continues to be paid, by a wide range of organisations for providing these skills on a professional basis. These include: NHS organisations, including NICE, NHS Choices, NHS Kidney Care, and others; publishers and medical education companies, including the BMJ Group, the Lancet group, Medscape, and others; professional organisations, including the British Thoracic Oncology Group, the European Society for Medical Oncology, NCEPOD, and others; charities and patients’ organisations, including the Roy Castle Lung Cancer Foundation and others; pharmaceutical companies, including Bayer, Boehringer Ingelheim, Novartis, and others; and communications agencies, including Publicis, Red Healthcare, and others. She has no stock options or shares in any pharmaceutical or healthcare companies; however, she invests in a personal pension, which may invest in these types of companies. She is managing director of Susan Mayor Limited, the company name under which she provides medical writing and communications services. 

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