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 outpatient review rate might be as low as 2.6%.

Background: Urgent clinician notification of low hemoglobin values is a common practice. The effect of such notification for samples obtained during an office visit is uncertain. Methods: We notified the attending physicians in 100 consecutive cases of outpatients with hemoglobin <80 g/L. We reviewed the medical charts of these patients with their personal physicians 1–2 months later. We considered transfusions unnecessary only when given to a clinically stable patient with probable iron deficiency anemia in the absence of chronic diseases that produce the anemia. Results: Overall, 47 (47%) of the patients were referred to the emergency room (ER), and 31 of the 47 (66%) were transfused. Increasing age and decreasing hemoglobin were associated with increased referral of patients to the ER. Six of 31 transfusions were unnecessary. An emergency transfusion was clearly indicated in only 3 of the 31 patients; the other patients were clinically stable. A modified notification strategy excluding microcytic samples >50 g/L would have detected these three patients. Over the follow-up period, no patient not referred to the ER died from complications of anemia, nor were any patients hospitalized with acute symptoms of low hemoglobin. Conclusion: In some settings, urgent notification of medical outpatient clinics of patients with hemoglobin <80 g/L may lead to unnecessary ER visits.

Adding a caveat to the urgent clinician notification that anaemia in clinically stable patients is not a medical emergency does not decrease the rate of ER referrals. Further studies are needed in order to find ways to decrease the number of inappropriate ER referrals.