Analysis of the performance of pathologists in the grading of bladder tumors.

Fifty-seven transurethrally resected bladder tumors were analyzed to determine whether different pathologists, using the World Health Organization grading system, graded the same bladder tumor differently (interindividual consistency) and whether the same pathologist graded a bladder tumor differently at different times (intraindividual consistency). Disturbingly high inter- and intraindividual inconsistency in the grading of bladder tumors was found. All pathologists showed essentially the same degree of intraindividual inconsistency: In almost 50 per cent of cases the tumor was graded differently at different times by the same pathologist. The inconsistencies might invalidate the usefulness of bladder tumor grading in clinical decision-making.