Gastroenterology

Prague C and M classification calculator

Enter the published formula inputs below to calculate and interpret this score.

Clinical inputs

Circumferential extent C

Allowed range: 0–9.84 in

Centimeters of circumferential columnar mucosa above the gastroesophageal junction. The junction is the proximal margin of the gastric folds.

Maximum extent M

Allowed range: 0–9.84 in

Maximum centimeters above the gastroesophageal junction, not the tongue length alone. M must be at least C. A shorter M is not replaced by C.

Squamous or columnar islands seen

Result

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Primary source

Sharma P et al. The development and validation of an endoscopic grading system for Barrett's esophagus: the Prague C & M criteria. Gastroenterology. 2006;131:1392-1399. DOI: 10.1053/j.gastro.2006.08.032. PMID: 17101315. C is the circumferential extent above the gastroesophageal junction in cm. M is the maximum extent above the gastroesophageal junction in cm, not the tongue length alone. The worked diagram is C 2 cm and M 5 cm, reported as C2M5. True squamous and columnar islands do not change C or M. M is at least C. Observers who recorded M below C had M replaced with C for analysis; this implementation does not replace a shorter M, and it withholds a class until M is at least C. The gastroesophageal junction used by the working group is the proximal margin of the gastric mucosal folds. Endoscopic changes under 1 cm above the junction had reliability coefficient 0.22, and changes of at least 1 cm had reliability coefficient 0.72. External reliability coefficients were 0.94 for C and 0.93 for M. The numeric result is M in cm, shown to one decimal. The reliability class follows the unrounded M. An M below 1 cm stays in the under-1-cm class when the displayed tenth is 1.0. An M of at least 1 cm is the at-least-1-cm class. (2006)

Scope: Endoscopic grading of a columnar-lined esophagus. Histology is a later step and is not part of the C and M length.

Last reviewed 2026-10-17

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Professional use only

For qualified clinicians. Independently verify inputs, calculations, source guidance, and applicability before any clinical action. This calculator does not replace clinical judgment.

Source: Sharma P et al. The development and validation of an endoscopic grading system for Barrett's esophagus: the Prague C & M criteria. Gastroenterology. 2006;131:1392-1399. DOI: 10.1053/j.gastro.2006.08.032. PMID: 17101315. C is the circumferential extent above the gastroesophageal junction in cm. M is the maximum extent above the gastroesophageal junction in cm, not the tongue length alone. The worked diagram is C 2 cm and M 5 cm, reported as C2M5. True squamous and columnar islands do not change C or M. M is at least C. Observers who recorded M below C had M replaced with C for analysis; this implementation does not replace a shorter M, and it withholds a class until M is at least C. The gastroesophageal junction used by the working group is the proximal margin of the gastric mucosal folds. Endoscopic changes under 1 cm above the junction had reliability coefficient 0.22, and changes of at least 1 cm had reliability coefficient 0.72. External reliability coefficients were 0.94 for C and 0.93 for M. The numeric result is M in cm, shown to one decimal. The reliability class follows the unrounded M. An M below 1 cm stays in the under-1-cm class when the displayed tenth is 1.0. An M of at least 1 cm is the at-least-1-cm class. (2006)

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Clinical inputs

Circumferential extent C (cm)Accepted range: 0 to 25
Maximum extent M (cm)Accepted range: 0 to 25
Squamous or columnar islands seen

Primary source

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