The blunder-rate in a clinical biochemistry service.

We describe a study undertaken to investigate the frequency and type of mistake detected in a large biochemistry laboratory. Blunders were recorded over three non-consecutive 3-week periods. The returns to the external quality assessment schemes during a 12-month period were also monitored. Despite changes in laboratory practice, the nature of the errors found has not altered substantially from those described by earlier investigators. The detected blunder rate was 0.3%.