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Health Dictionary

Reliable, easy-to-read patient information on common medical conditions — written in plain language, free of jargon, and grounded in current evidence. Browse the most frequent diagnoses, understand what they mean for everyday life, and learn which steps and questions help you have a focused conversation with your doctor.

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Crohn's disease screening

Introduction

Overview

Overview

No professional society recommends screening asymptomatic members of the general population for Crohn’s disease. In practice, “screening” covers three separate activities. The first is case finding in symptomatic patients, where fecal calprotectin (FC) is the guideline-endorsed first-line, non-invasive test for deciding who needs endoscopy.[1] The second is risk stratification of asymptomatic first-degree relatives (FDRs), which is still investigational and confined to research and prevention-trial settings.[2] The third is colorectal cancer (CRC) surveillance in established Crohn’s colitis, a formal, guideline-mandated program whose start time and intervals differ between societies.[3][4]

Screening

Screening

Population Screening of Asymptomatic Individuals

  • Not recommended. Major society guidelines (ACG, AGA, ECCO, BSG, NICE) contain no recommendation to screen the asymptomatic general population for Crohn’s disease. Current research aims to build validated, multidimensional predictive tools for enriched high-risk groups, not for the general population.[2]
  • Genetic testing has no screening role. Genetic testing is reserved for suspected monogenic disease, mainly very-early-onset inflammatory bowel disease (IBD) presenting before age 6, or IBD with immunodeficiency or syndromic features.[5] It should not be used to screen asymptomatic relatives.

Case Finding in Symptomatic Patients

Fecal calprotectin

  • Guideline status: The ACG recommends that FC be considered to help distinguish IBD from irritable bowel syndrome (IBS).[1]
  • Rule-out value: FC is most useful for its negative predictive value. In primary care, an FC ≤40 μg/g corresponds to a <1% probability of IBD.[6][7]
Fecal calprotectin performance for endoscopically active Crohn’s disease (AGA 2023)
FC cutoff (μg/g) Sensitivity Specificity Practical role
50 ± 50 88% 67% Rule-out
150 ± 50 81% 72% Intermediate
250 ± 50 76% 74% Favors rule-in
  • Combined triage: Pairing the Red Flags Index (≥8) with FC >250 μg/g raised the positive predictive value from 4% to 21% and the negative predictive value from 97% to 100%.[6]
  • Small-bowel limitation: FC is less sensitive for small-bowel inflammation. In a pooled analysis of 214 patients who underwent capsule endoscopy, median FC for comparable inflammation rose stepwise:[8]
    • proximal small bowel: 63 μg/g
    • distal small bowel: 190 μg/g
    • colon: 542 μg/g
  • A normal FC therefore does not exclude isolated proximal or small-bowel CD. When clinical suspicion is high, proceed to capsule endoscopy or cross-sectional enterography.[9]

Supporting laboratory markers

  • C-reactive protein, erythrocyte sedimentation rate, CBC, and albumin can raise suspicion of CD but are neither sensitive nor specific. Many patients with mild active inflammation have normal CRP and ESR, so a normal panel does not exclude CD.[1]
  • CRP ≥2.7 mg/dL has a positive predictive value of about 90% but poor sensitivity.[7]
  • Serologic markers such as ASCA and pANCA are not sensitive or specific enough for diagnostic screening.[10]

Practical case-finding approach

This approach applies to patients with chronic diarrhea and/or abdominal pain:[1][11][6]

  1. Obtain FC, CBC, CRP, a metabolic panel, and stool studies, including Clostridioides difficile testing, to exclude infection.
  2. If FC is ≤40–50 μg/g and there are no alarm features, IBD is unlikely; evaluate for functional or alternative diagnoses.
  3. If FC is ≥250 μg/g, alarm features are present (rectal bleeding, weight loss, perianal disease, anemia), or inflammatory markers are abnormal, refer for ileocolonoscopy with biopsies, with or without cross-sectional imaging.
  4. If FC is ~50–250 μg/g, repeat FC and/or proceed to endoscopy based on pretest probability.
  5. If small-bowel CD is suspected despite a low FC, pursue small-bowel imaging or capsule endoscopy.

Risk Stratification of First-Degree Relatives (Investigational)

  • Familial risk: In a Swedish nationwide study, people with IBD had about 3.5-fold higher odds of having an affected parent or full sibling. The odds were highest for pediatric-onset CD (OR 10.6). Risk rose with the number of affected FDRs. The 10-year cumulative incidence of IBD in full siblings of incident cases was 1.7%, compared with 0.4% in siblings of reference individuals.[12]
  • Subclinical inflammation: In the CCC-GEM cohort, healthy FDRs from multiplex families (≥2 affected relatives) had higher FC, a distinct fecal microbial signature, and a higher risk of developing CD than FDRs from simplex families.[13]
  • Practical counseling: Counsel FDRs to seek prompt evaluation if symptoms develop. Advise smoking cessation, since smoking is a strong environmental risk factor for CD within IBD families.[14][9]

Colorectal Cancer Surveillance in Crohn’s Colitis

Unlike population screening, colonoscopic surveillance is a formal mandate once colonic CD is established. All societies agree that surveillance is indicated; they differ on when to start and how to set intervals. Detailed dysplasia management belongs in the complications/cancer microchapter.

Colorectal cancer surveillance in colonic Crohn’s disease: guideline comparison
Society Start of surveillance Interval approach
BSG 2025 ~8 years after symptom onset Risk-stratified, including a web-based multivariate risk calculator[3]
ECCO 2023 ~8 years after symptom onset Set by disease phenotype and additional risk factors[4]
AGA 2021 8–10 years after diagnosis Every 1–5 years based on risk factors (e.g., family history of CRC, quality of prior examinations)[15]
NICE CG118 10 years after symptom onset, for Crohn’s colitis involving >1 colonic segment Low risk: 5 years; intermediate: 3 years; high risk (e.g., PSC, recent stricture or dysplasia, FDR with CRC <50 years): 1 year[16]
  • Primary sclerosing cholangitis (PSC) is a high-risk modifier. Surveillance colonoscopy should begin at the time of PSC diagnosis, regardless of colitis duration, and continue annually.[4][16]
References

References

  1. ↑ 1.0 1.1 1.2 1.3 Lichtenstein GR, Loftus EV, Isaacs KL, Regueiro MD, Gerson LB, Sands BE (2018). “ACG Clinical Guideline: Management of Crohn’s Disease in Adults”. Am J Gastroenterol. 113 (4): 481–517. doi:10.1038/ajg.2018.27. PMID 29610508.
  2. ↑ 2.0 2.1 Bronze S; et al. (2024). “Review article: Prevention of inflammatory bowel disease—The path forward”. Aliment Pharmacol Ther. PMID 39403049 Check |pmid= value (help).
  3. ↑ 3.0 3.1 East JE, Gordon M, Nigam GB, Sinopoulou V, Bateman AC, Din S, Iacucci M, Kabir M, Lamb CA, Wilson A, Al Bakir I, Dhar A, Dolwani S, Faiz O, Hart A, Hayee B, Healey C, Leedham SJ, Novelli MR, Raine T, Rutter MD, Shepherd NA, Subramanian V, Vance M, Wakeman R, White L, Trudgill NJ, Morris AJ (2026). “British Society of Gastroenterology guidelines on colorectal surveillance in inflammatory bowel disease”. Gut. 75 (3): 442–475. doi:10.1136/gutjnl-2025-335023.
  4. ↑ 4.0 4.1 4.2 Gordon H, Biancone L, Fiorino G, Katsanos KH, Kopylov U, Al Sulais E; et al. (2023). “ECCO Guidelines on Inflammatory Bowel Disease and Malignancies”. J Crohns Colitis. 17 (6): 827–854. doi:10.1093/ecco-jcc/jjac187. PMID 36528797 Check |pmid= value (help).
  5. ↑ Uhlig HH, Schwerd T, Koletzko S; et al. (2014). “The diagnostic approach to monogenic very early onset inflammatory bowel disease”. Gastroenterology. 147 (5): 990–1007.e3. PMID 25058236.
  6. ↑ 6.0 6.1 6.2 Agrawal M, Spencer EA, Colombel JF, Ungaro RC (2021). “Approach to the Management of Recently Diagnosed Inflammatory Bowel Disease Patients: A User’s Guide for Adult and Pediatric Gastroenterologists”. Gastroenterology.
  7. ↑ 7.0 7.1 Dolinger M, Torres J, Vermeire S (2024). “Crohn’s disease”. Lancet: 1177–1191.
  8. ↑ Israeli IBD Research Nucleus (IIRN) (2025). “Fecal Calprotectin Diagnostic Level Gradient Along the Small Bowel in Patients With Crohn’s Disease”. J Crohns Colitis. 19: jjae123. PMID 39120437 Check |pmid= value (help).
  9. ↑ 9.0 9.1 Cushing K, Higgins PDR (2021). “Management of Crohn Disease: A Review”. JAMA. 325 (1): 69–80. doi:10.1001/jama.2020.18936. PMID 33399844 Check |pmid= value (help).
  10. ↑ Torres J, Mehandru S, Colombel JF, Peyrin-Biroulet L (2017). “Crohn’s disease”. Lancet. 389 (10080): 1741–1755. doi:10.1016/S0140-6736(16)31711-1.
  11. ↑ Invalid <ref> tag; no text was provided for refs named Ananthakrishnan2023
  12. ↑ Halfvarson J, Ludvigsson JF, Bresso F, Askling J, Sachs MC, Olén O (2022). “Age determines the risk of familial inflammatory bowel disease—A nationwide study”. Aliment Pharmacol Ther. 56 (3): 491–500. doi:10.1111/apt.16938.
  13. ↑ Olivera PA, Martinez-Lozano H, Leibovitzh H, Xue M, Neustaeter A, Espin-Garcia O, et al.; CCC GEM Project Research Consortium (2025). “Healthy First-Degree Relatives From Multiplex Families vs Simplex Families Have Higher Subclinical Intestinal Inflammation, a Distinct Fecal Microbial Signature, and Harbor a Higher Risk of Developing Crohn’s Disease”. Gastroenterology. 168 (1): 99–110.e2. doi:10.1053/j.gastro.2024.08.031. PMID 39236898 Check |pmid= value (help).
  14. ↑ Bridger S; et al. (2002). “In siblings with similar genetic susceptibility for inflammatory bowel disease, smokers tend to develop Crohn’s disease and non-smokers develop ulcerative colitis”. Gut. 51 (1): 21.
  15. ↑ Murthy SK, Feuerstein JD, Nguyen GC, Velayos FS (2021). “AGA Clinical Practice Update on Endoscopic Surveillance and Management of Colorectal Dysplasia in Inflammatory Bowel Diseases: Expert Review”. Gastroenterology. 161 (3): 1043–1051.e4.
  16. ↑ 16.0 16.1 National Institute for Health and Care Excellence. Colorectal cancer prevention: colonoscopic surveillance in adults with ulcerative colitis, Crohn’s disease or adenomas (CG118). 2011. https://www.nice.org.uk/guidance/cg118

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] ; Associate Editor(s)-in-Chief: Fahad Hasan, M.D.[2] Aditya Ganti M.B.B.S. [3]