The dark side of the gastric biopsy

Based on the assumption that both sides of a gastric biopsy sample have a s imilar appearance, the choice of which side of a specimen is to be sectione d is usually random, We tested the hypothesis that the diagnosis reached by examining the two sides of a gastric biopsy may differ. Eighty-one antral biopsy specimens from patients with neither focal lesions nor previous gast ric surgery were evaluated. After preparing 8-10 sections from each of the two opposite faces of each biopsy, sections were scored for Helicobacter py lori, activity atrophy, intestinal metaplasia, lymphoid follicles. The pres ence of other lesions was also noted. Intrabiopsy agreement (the consistenc y in the identification of histological lesions on the opposite sides of th e same sample) was calculated by using kappa statistics, A kappa value lowe r than 0.5 was considered "poor"; between 0.51 and 1.00 "moderate to excell ent." The intrabiopsy agreement kappa values were: activity = 0.83, atrophy = 0.54, intestinal metaplasia = 0.51 and lymphoid follicles = 0.19. A mean of 42 serial sections (ranging from a mean of 22 for lymphoid follicles to a mean of 81 for xanthogranulomata) was needed to achieve an excellent (ie , kappa greater than or equal to 0.75) intrabiopsy agreement between the fe atures showed at the opposite sides of a biopsy specimen. Intrabiopsy varia bility may represent a hitherto unrecognized source of error, and it should be minimized or avoided. In a research context information about the numbe r of sections examined from a biopsy would provide a crucial element necess ary to evaluate the accuracy of the histological data. Copyright (C) 1999 b y W.B. Saunders Company.