The rate of manual peripheral blood smear reviews in outpatients.

BACKGROUND The International Consensus Group for Hematology Review recommends manual blood smears for new findings from automated complete blood cell (CBC) tests. However, in outpatients, the rate of peripheral manual blood smear reviews is uncertain, as is the effect of historical results on this rate. METHODS In a prospective cohort study of 687,955 members of a health maintenance organization, we extracted 39,759 consecutive automated CBC test results and determined the rate of manual peripheral smear reviews that were indicated using different triggering criteria, and historical results. RESULTS Individual triggering values increased from 10.7% to 19.5% when comparing our criteria to those of the consensus criteria. The proportion of CBC test results with at least one triggering value was 7.2% using our criteria, compared to 13.9% with the inclusion of a mean corpuscular volume <75 and a plus one immature granulocyte flag according to the consensus committee. Availability of historical data decreased our peripheral smear review rate to 2.6%. CONCLUSIONS The peripheral smear review rate in outpatients using the consensus criteria was higher than with our less stringent criteria. If historical data are available and no clinical utility is demonstrated for the additional consensus criteria, an acceptable out-patient review rate might be as low as 2.6%.