Clinical decision support
Practice guidelines and risk calculators
Third-party guidelines and prediction tools relevant to Crohn’s disease, each independently verified against PubMed. These are external documents and tools, linked, not reproduced, and not evidence-gated by this site.
Read the access and validation labels. Very few published IBD prediction tools are simultaneously a live free calculator, externally validated, and validated for the decision you are about to make. Where a tool is formula-only, or was validated only in its derivation cohort, that is stated rather than hidden behind a link. 5 further item(s) found by this review are withheld pending clinician sign-off rather than published unverified.
Practice guidelines
- ECCO Guidelines on Therapeutics in Crohn's Disease: Surgical Treatment
- The American Society of Colon and Rectal Surgeons Clinical Practice Guidelines for the Surgical Management of Crohn's Disease
- ECCO Guidelines on Therapeutics in Crohn's Disease: Medical Treatment
- ACG Clinical Guideline: Management of Crohn's Disease in Adults
- AGA Living Clinical Practice Guideline on the Pharmacologic Management of Moderate-to-Severe Crohn's Disease
- British Society of Gastroenterology guidelines on inflammatory bowel disease in adults: 2025
- American Gastroenterological Association Institute Guideline on the Management of Crohn's Disease After Surgical Resection
- AGA Clinical Practice Guideline on the Role of Biomarkers for the Management of Crohn's Disease
- ECCO-ESGAR-ESP-IBUS Guideline on Diagnostics and Monitoring of Patients with Inflammatory Bowel Disease: Part 1
- ESPEN guideline on Clinical Nutrition in inflammatory bowel disease
Risk calculators and prediction tools
- ACS NSQIP Surgical Risk Calculator (v4.0.4) Note: Externally validated in general surgical populations, NOT calibrated for Crohn's disease. It has no field for corticosteroid DOSE or duration, biologic/small-molecule exposure, penetrating vs stricturing phenotype, preoperative abscess, hypoalbuminaemia as a graded variable, number of prior resections, or nutritional status, i.e. it omits most of what actually drives risk in a Crohn's resection. Use it as a generic perioperative baseline for consent, never as a Crohn's-specific risk estimate.
- Postoperative Crohn's disease recurrence nomogram (Allez et al., biologic era) Note: The best-validated postoperative recurrence tool available (prospective multicentre derivation, n=632, plus 2 independent international validation cohorts), but discrimination is only modest, AUC 0.72, so it stratifies groups rather than resolving individual cases. The endpoint is 1-year ENDOSCOPIC recurrence, a surrogate for surgical recurrence. Published March 2026, so independent replication beyond the authors' own validation cohorts does not yet exist. There is no hosted implementation: the nomogram must be read off the figure in the paywalled paper.
- Nomogram for postoperative intra-abdominal septic complications after bowel resection and primary anastomosis in Crohn's disease (Zhu et al.) Note: DERIVATION ONLY, the authors themselves state that 'a major limitation of this model is the lack of external validation', so the reported AUC of 0.823 is apparent performance and will be optimistic. Single-centre Chinese cohort (n=949, 2011–2017) in which preoperative exclusive enteral nutrition was routine and strongly protective (OR 0.19); that practice pattern does not transfer to most Western centres, so the model's calibration elsewhere is unknown. Biologic exposure is captured only as infliximab. Do not use it to justify or to withhold a diverting stoma without local recalibration.
Also on MDCalc
These are established instruments already hosted as free, working calculators by MDCalc. We link them rather than rebuild them. Our own decision-support tools above cover what MDCalc does not, and every link below was verified against MDCalc directly.
- Montreal Classification for IBD Note: A PHENOTYPE classification, not a prediction model. Extent should be recorded as the maximum ever documented, not the most recent endoscopic appearance, which underestimates true extent in quiescent disease.
- Crohn's Disease Activity Index (CDAI) Note: Correlates POORLY with endoscopic inflammation. A normal CDAI does not exclude active disease. Explicitly invalid in stricturing/fistulising disease, after extensive resection, and in patients with a stoma. Pair with CRP/faecal calprotectin and imaging.
- Harvey-Bradshaw Index (HBI) for Crohn's Disease Note: Symptom-driven, so it shares CDAI's blindness to endoscopic activity. The severity bands are from the literature, not from MDCalc's page.
- Simplified Endoscopic Activity Score for Crohn's Disease (SES-CD) Note: Requires full ileocolonoscopy with all five segments assessed; a partial exam is not scoreable. Objective counterpart to the symptom-based CDAI/HBI.
- Pediatric Crohn's Disease Activity Index (PCDAI) Note: PAEDIATRIC ONLY. The growth items are the reason it exists. Do not substitute an adult index in children.
- Surgical Apgar Score (SAS) Note: Calculated AFTER the operation, so it informs postoperative disposition, never the decision to operate. Not validated specifically in IBD surgery.
Guideline summaries hosted by MDCalc:
- ACG Clinical Guideline: Management of Crohn's Disease in Adults (via MDCalc) Note: Check the publication date against the current ACG listing before presenting it as current.
- ACG: Preventive Care in Inflammatory Bowel Disease (via MDCalc) Note: Directly relevant before starting biologics or immunomodulators, and a frequent gap in surgical clinics.