Diagnostic efficacy of additional step-sections in colorectal biopsies originally diagnosed as normal.

Multiple "step-sections" are prepared for many diagnostic biopsies, but tissue is usually left in the block for possible additional studies. We sought to determine the frequency with which sampling the remaining tissue with additional step-sections would reveal pathologic abnormality in a series of colorectal biopsies originally diagnosed as normal. Slides of 232 cases were reviewed and classified into 7 standard diagnostic categories.