Acute appendicitis

Last reviewed: 1 Jan 2023
Last updated: 11 Aug 2022



History and exam

Key diagnostic factors

  • abdominal pain
  • anorexia
  • nausea and vomiting
  • right lower quadrant tenderness
  • high’ or ‘intermediate’ risk score
  • tense, rigid abdomen
  • hypotension and tachycardia
  • palpable mass
Full details

Other diagnostic factors

  • age of occurrence
  • low-grade pyrexia
  • flushed face and a fetor
  • reduced bowel sounds
  • loose stool
  • constipation
  • flexed right hip (psoas sign)
Full details

Risk factors

  • low dietary fibre
  • improved personal hygiene
  • smoking
Full details

Diagnostic investigations

1st investigations to order

  • FBC
  • CRP
  • abdominal ultrasound
  • contrast-enhanced abdominal CT
Full details

Investigations to consider

  • urinalysis
  • pregnancy test
  • group and save
  • abdominal MRI
Full details

Treatment algorithm


uncomplicated appendicitis: adults

uncomplicated appendicitis: children

complicated appendicitis: adults

complicated appendicitis: children


Expert advisers

John Abercrombie, FRCS

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.


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

Dileep N. Lobo, MS, DM, FRCS, FACS

Professor of Gastrointestinal Surgery

National Institute for Health Research, Nottingham Digestive Diseases Biomedical Research Unit

Nottingham University Hospitals and University of Nottingham, Queen's Medical Centre



DNL declares that he has no competing interests. DNL is an author of an article cited in the topic.

Peer reviewers

Sarah Richards

General Surgeon

Royal United Hospitals

Bath NHS Foundation Trust



SR is a specialty advisor in emergency general surgery to the Royal College of Surgeons and an honorary senior clinical lecturer and examiner for the University of Bristol medical school.


SR declares that she has no competing interests.

Kokila Lakhoo, PhD, FRCS, FCS (Paediatrics) MRCPCH, MBCHB

Consultant Paediatric Surgeon

Children’s Hospital in Oxford and the University of Oxford



KL declares that she has no competing interests.


Tessa Davis

Section Editor, BMJ Best Practice

Consultant in Paediatric Emergency Medicine

Royal London Hospital




TD declares that she has no competing interests.

Annabel Sidwell

Section Editor, BMJ Best Practice


AS declares that she has no competing interests.

Jo Haynes

Head of Editorial, BMJ Knowledge Centre


JH declares that she has no competing interests.

Susan Mayor

Lead Section Editor, BMJ Best Practice


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 the National Institute for Health and Care Excellence, 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, the National Confidential Enquiry into Patient Outcome and Death, 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.

Tannaz Aliabadi-Oglesby

Lead Section Editor, BMJ Best Practice


TAO declares that she has no competing interests.

Julie Costello

Comorbidities Editor, BMJ Best Practice


JC declares that she has no competing interests.

Adam Mitchell

Drug Editor, BMJ Best Practice


AM declares that he has no competing interests.

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