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Last reviewed: 21 Apr 2025
Last updated: 11 Apr 2025

Summary

Definition

History and exam

Key diagnostic factors

  • presence of risk factors
  • abdominal pain
  • prolonged diarrhoea
  • perianal lesions

Other diagnostic factors

  • bowel obstruction
  • blood in stools
  • fatigue
  • abdominal tenderness
  • weight loss
  • fever
  • oral lesions
  • abdominal mass
  • extra-intestinal manifestations (e.g., erythema nodosum or pyoderma gangrenosum)

Risk factors

  • white ethnicity
  • Ashkenazi Jewish ancestry
  • age 15-40 or 50-60 years
  • family history of CD
  • use of antibiotics
  • cigarette smoking
  • diet high in refined sugar
  • diet low in fibre
  • diet high in ultra-processed foods
  • use of oral contraceptive pill
  • not breastfed
  • use of non-steroidal anti-inflammatory drugs (NSAIDs)

Diagnostic investigations

1st investigations to order

  • FBC
  • iron studies (serum iron, serum ferritin, total iron binding capacity [TIBC], transferrin saturation)
  • serum vitamin B12
  • serum folate
  • comprehensive metabolic panel (CMP)
  • CRP and erythrocyte sedimentation rate (ESR)
  • stool testing
  • Yersinia enterocolitica serology
  • plain abdominal x-ray
  • MRI abdomen/pelvis
  • CT abdomen

Investigations to consider

  • abdominal and pelvic ultrasonography
  • ileocolonoscopy
  • tissue biopsy
  • oesophagogastroduodenoscopy
  • wireless capsule endoscopy
  • faecal calprotectin

Emerging tests

  • serological markers

Treatment algorithm

Contributors

Authors

Lucy Charlotte Hicks, MBBS, PhD, FHEA, MRCP

Consultant Gastroenterologist

Department of Gastroenterology

St Mary's Hospital

Imperial College Healthcare NHS Trust

Honorary Senior Clinical Lecturer

Imperial College

London

UK

Disclosures

LCH declares that she has no competing interests.

Georgia Woodfield, MBChB, MSc, PhD

Specialist Registrar in Gastroenterology and General Medicine

Imperial College Healthcare NHS Trust

Research Fellow

Imperial College London

London

UK

Disclosures

GW declares that she has no competing interests.

Acknowledgements

Dr Georgia Woodfield and Dr Lucy Charlotte Hicks would like to gratefully acknowledge Mr George Reese, Dr Pranav H. Patel, Dr Philip J. Smith, Dr Charlotte Ford, Dr Wissam Bleibel, Dr Bishal Mainali, Dr Chandrashekhar Thukral, and Dr Mark A. Peppercorn, the previous contributors to this topic.

Disclosures

GR is an author of a number of references cited in this topic. PHP, PJS, CF, WB, BM, CT, and MAP declare that they have no competing interests.

Peer reviewers

Kiron M. Das, MD, PhD, FACP, FRCP

Chief of Gastroenterology & Hepatology

Professor of Medicine

Director of Crohn's & Colitis Center of New Jersey

New Brunswick

NJ

Disclosures

KMD declares that he has no competing interests.

John Mansfield, MA, MD, FRCP

Consultant Gastroenterologist and Senior Lecturer

Royal Victoria Infirmary

Newcastle upon Tyne Hospitals NHS Foundation Trust and Newcastle University

Newcastle upon Tyne

UK

Disclosures

JM declares that he has no competing interests.

References

Our in-house evidence and editorial teams collaborate with international expert contributors and peer reviewers to ensure that we provide access to the most clinically relevant information possible.

Key articles

Ooi CJ, Makharia GK, Hilmi I, et al. Asia Pacific consensus statements on Crohn's disease. Part 1: definition, diagnosis, and epidemiology. J Gastroenterol Hepatol. 2016 Jan;31(1):45-55.Full text  Abstract

Lichtenstein GR, Loftus EV, Isaacs KL, et al. ACG clinical guideline: management of Crohn's disease in adults. Am J Gastroenterol. 2018 Apr;113(4):481-517.Full text  Abstract

Gomollón F, Dignass A, Annese V, et al. 3rd European evidence-based consensus on the diagnosis and management of Crohn's disease 2016: Part 1: diagnosis and medical management. J Crohns Colitis. 2017 Jan;11(1):3-25.Full text  Abstract

Torres J, Bonovas S, Doherty G, et al. ECCO guidelines on therapeutics in Crohn's disease: medical treatment. J Crohns Colitis. 2020 Jan 1;14(1):4-22.Full text  Abstract

Adamina M, Bonovas S, Raine T, et al. ECCO guidelines on therapeutics in Crohn's disease: surgical treatment. J Crohns Colitis. 2020 Feb 10;14(2):155-68.Full text  Abstract

Feuerstein JD, Ho EY, Shmidt E, et al. AGA clinical practice guidelines on the medical management of moderate to severe luminal and perianal fistulizing Crohn's disease. Gastroenterology. 2021 Jun;160(7):2496-508.Full text  Abstract

Gionchetti P, Dignass A, Danese S, et al. 3rd European evidence-based consensus on the diagnosis and management of Crohn’s disease 2016: Part 2: surgical management and special situations. J Crohns Colitis. 2017 Feb;11(2):135-49.Full text  Abstract

Reference articles

A full list of sources referenced in this topic is available here.

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