Introduction: A peripheral blood smear (PBS) review by a pathologist is an invaluable diagnostic tool. However, it is time-consuming and rarely adds any new information beyond what is obtained by the complete blood count with differential (CBC) using the latest automated analyzers in most patients. A PBS review typically takes 10-15 minutes for the trained medical laboratory scientists (MLS) to prepare the smear and 10-15 minutes for the pathologist to review it.
Our center saw a steady rise in the number of physician-ordered PBS from 2017 to 2022, most of which did not add any new diagnostic information. In order to address this issue, an inter-departmental team was formed. In this study, we report the steps taken to use PBS review judiciously, its impact on the number of PBS ordered, and its clinical yield.
Methods: In our center, the analyzer (Sysmex) flags abnormal results on CBC, which are then verified by morphologic assessment through digital morphology analysis (CellaVision) and light microscopy by MLS. Cases with atypical findings are then sent to a pathologist for review. In addition to the lab-initiated PBS, physicians can order PBS for review by a pathologist. Due to the increasing number of provider-ordered PBS, and the nearly constant lab-initiated PBS requests, a team comprising two hematopathologists, and a hematologist was formed for targeted in-person provider education, the creation of order sets on the electronic health record system for anemia evaluation, and the revision of the criteria for PBS review. These changes were implemented in September 2023. We then assessed these changes' impact on the number of PBS reviews and their diagnostic yield.
Results: From 2017 to 2022, the number of physician-ordered PBS nearly doubled (1352 in 2017 vs. 2611 in 2022), while the number of lab-initiated PBS stayed stable during the same period (1718 in 2017 vs. 1475 in 2022). Between January 2023 and August 2023 (8 months), the number of physician-ordered PBS was 1688, averaging 211/month. After implementation of the changes in September 2023, from October 2023 to May 2024 (8 months), the number of physician-ordered PBS significantly decreased to 1041, averaging 130/month (p < 0.001). During the same time, lab-initiated PBS remained stable from 107/month to 95/month (p = 0.11). There was a significant decrease in the total number of PBS ordered from 318/month to 225/month (p < 0.001). This translated to a total time savings of ~ 31.0 - 46.6 hours per month combined for both MLS and pathologists (~ 10-15 minutes of time per PBS for both MLS and pathologists).
The next step was to assess if there was any change in the clinical yield of this test. For this, an in-depth analysis of all the physician-ordered PBS requests was performed for 4 consecutive weeks in the months of May 2022, May 2023 (prior to the implementation of changes), and May 2024 (after the implementation of changes). A PBS review was determined to have potential clinical value if the pathologist interpretation provided information not detected by the automated CBC and might have prompted further evaluation or changes in clinical care, or if the PBS interpretation was quoted in a follow-up clinical note. In May 2022, 199 physician-ordered PBS were performed, of which 6 (3%) PBS cases provided potential clinical value. Similarly, in May 2023, 189 physician-ordered PBS were performed, of which 6 (3%) PBS cases provided potential clinical value. In May 2024, 115 physician-ordered PBS were performed, of which 5 (4%) PBS cases provided potential clinical value.
Conclusion: By providing targeted in-person provider education, creating order sets for anemia evaluation, and revising the criteria for PBS review, we were able to significantly reduce the number of physician-ordered PBS, and the total number of PBS ordered. This translated to a total time savings of ~ 31.0 - 46.6 hours per month combined for both MLS and pathologists, without compromising on the potential clinical yield. With the reduction in the number of PBS ordered, the relative diagnostic yield of the PBS increased from 3% to 4%. This study highlights the way an inter-departmental team can work together to improve the quality of healthcare and ensure judicious use of resources.
No relevant conflicts of interest to declare.
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