Prague C & M Classification for Barrett's Esophagus

Why use it

The Prague C & M Classification provides a reproducible, standardized language for describing Barrett's esophagus extent across endoscopists and institutions, enabling accurate longitudinal monitoring, risk stratification, and communication. Segment length is the strongest endoscopic predictor of dysplasia and adenocarcinoma risk — LSBE (M ≥ 3 cm) carries a substantially higher risk of progression than SSBE. Accurate classification also determines surveillance intervals per international guidelines and influences decisions regarding endoscopic eradication therapy.

About

The Prague C & M Classification is the internationally validated endoscopic grading system for Barrett's esophagus (BE), developed by Sharma and colleagues on behalf of the International Working Group for the Classification of Oesophagitis (IWGCO) and published in Gastroenterology in 2006. The classification defines two measurable endoscopic parameters: (C) the circumferential extent of columnar-lined esophagus measured in centimeters proximal to the top of the gastric folds (TGF), and (M) the maximal extent of any columnar-lined segment (including tongues or islands) measured in centimeters from the TGF. Both C and M values are rounded to the nearest centimeter, and C must always be ≤ M. For example, a segment with 3 cm of circumferential columnar lining and a tongue extending to 5 cm above the TGF is classified as C3M5. The classification also recognizes C0M0 when specialized intestinal metaplasia (SIM) is detected on biopsies of an endoscopically normal-appearing gastroesophageal junction — known as ultrashort or 'ultrashort' BE. The Prague classification has been validated in multiple international studies and demonstrates good inter-observer agreement (weighted kappa 0.72–0.90 for M and 0.75–0.92 for C). It is endorsed by the British Society of Gastroenterology (BSG), American Gastroenterological Association (AGA), and European Society of Gastrointestinal Endoscopy (ESGE) as the standard for reporting BE extent at endoscopy.

When to use

• Any upper endoscopy where columnar-lined esophageal mucosa is identified proximal to the gastroesophageal junction
• Surveillance endoscopies in established Barrett's esophagus to document interval change in segment length
• Pre-treatment assessment before endoscopic eradication therapy (EET) for dysplastic Barrett's
• Post-EET surveillance to document completeness of eradication and detect recurrence
• Research and clinical trials requiring standardized BE characterization
• Biopsies of the normal-appearing GEJ when intestinal metaplasia is suspected (C0M0 classification)

Formula

Pearls & pitfalls

• C must always be ≤ M. A finding where C > M indicates a measurement error — re-measure carefully.
• The top of the gastric folds (TGF) — not the squamocolumnar junction (SCZ) or diaphragmatic pinch — is the reference landmark for both C and M measurements. Use TGF identified in partial insufflation.
• Short segment BE (SSBE) is defined as M < 3 cm; Long segment BE (LSBE) is M ≥ 3 cm. LSBE carries a ~5–10× higher absolute cancer risk than SSBE.
• The annual incidence of esophageal adenocarcinoma in BE without dysplasia is approximately 0.1–0.3% per year overall, but risk correlates strongly with segment length.
• Biopsies using the Seattle protocol (4-quadrant biopsies every 1–2 cm throughout the BE segment plus targeted biopsies of mucosal irregularities) are required for accurate dysplasia detection — the Prague classification describes extent, not histology.
• After endoscopic eradication therapy (EET), BE recurrence is most common at the neo-squamocolumnar junction — report C and M at post-ablation endoscopy using the same landmarks.
• The Prague classification does not grade dysplasia — dysplasia status must be documented separately and confirmed by a second pathologist experienced in gastrointestinal pathology.
• Columnar metaplasia without intestinal metaplasia (SIM) is not universally accepted as 'true' Barrett's esophagus in all guidelines — the BSG requires SIM on biopsy, whereas older AGA definitions required endoscopic BE ≥ 3 cm regardless of histology. Current AGA and ACG guidelines require both endoscopic and histological confirmation.
• Inter-observer variability in identifying the TGF is the main source of disagreement in Prague classification — standardize technique by measuring during partial withdrawal with moderate insufflation.

Next steps

C0M0 with SIM confirmed on biopsy (ultrashort BE): No surveillance recommended in most guidelines (low cancer risk; may not represent true BE). C0-M<1 cm (very short tongues/islands): Clinical management per local guidelines; many experts do not recommend formal surveillance. M<3 cm (Short Segment BE, SSBE): Surveillance every 3–5 years if no dysplasia; every 3 years if persistent no-dysplasia on 2 consecutive exams. M≥3 cm (Long Segment BE, LSBE): Surveillance every 2–3 years if no dysplasia. Low-Grade Dysplasia (LGD): Confirmed by expert pathologist; offer endoscopic eradication therapy (EET) or intensive 6-month surveillance. High-Grade Dysplasia (HGD): Endoscopic eradication therapy (endoscopic mucosal resection + radiofrequency ablation) strongly recommended. Intramucosal carcinoma (T1a): Endoscopic eradication therapy; multidisciplinary discussion.

Evidence

Sharma P et al. The development and validation of an endoscopic grading system for Barrett's esophagus: The Prague C & M criteria. Gastroenterology. 2006;131(5):1392-1399. PMID:17101315. Validation: interobserver agreement weighted kappa 0.72–0.92. Prospective multicenter validation in 29 endoscopists across 8 countries. Segment length is independently associated with dysplasia risk: Sikkema M et al. Risk factors for neoplastic progression in patients with Barrett's esophagus. Am J Gastroenterol. 2011. Cancer risk: SSBE ~0.1-0.2%/year; LSBE ~0.5-1.0%/year. ESGE/BSG/AGA guidelines endorse Prague as the standard reporting system.

References

1. Sharma P et al. The development and validation of an endoscopic grading system for Barrett's esophagus: the Prague C & M criteria. Gastroenterology. 2006;131(5):1392-1399. — link
2. Weusten B et al. Endoscopic management of Barrett's esophagus: European Society of Gastrointestinal Endoscopy (ESGE) Position Statement. Endoscopy. 2017;49(2):191-198. — link
3. Fitzgerald RC et al. British Society of Gastroenterology guidelines on the diagnosis and management of Barrett's oesophagus. Gut. 2014;63(1):7-42. — link
4. Shaheen NJ et al. ACG Clinical Guideline: Diagnosis and Management of Barrett's Esophagus. Am J Gastroenterol. 2016;111(1):30-50. — link
5. Sikkema M et al. Risk factors for neoplastic progression in patients with Barrett's esophagus: a case-cohort study. Am J Gastroenterol. 2011;106(7):1231-1238. — link