When and how to grade Barrett's columnar metaplasia: the Prague system.

Barrett's oesophagus (BO), a well-known precursor for oesophageal adenocarcinoma has been generating a great deal of controversy. The initial step in diagnosing BO requires an accurate endoscopic recognition of the columnar lined oesophagus. A reliable diagnosis of BO depends on its effective endoscopic recognition based on the key anatomic landmarks, followed by histological sampling of the columnar-lined epithelium. Precise localisation of the gastrooesophageal junction is pivotal in the endoscopic diagnosis of BO. Multiple ad-hoc grading systems and terminologies of BO have been proposed based on the Z-line appearance, presence or absence of intestinal metaplasia, and the length of Barrett's segment. However, a universally accepted standardised endoscopic grading system of BO is lacking. The Prague C&M criteria, developed by a subgroup of the International Working Group for the Classification of Oesophagitis, are the first explicit, consensus-driven, clinically relevant criteria for the endoscopic recognition and grading of BO that may be useful in both clinical practice and research trials.