A prospective, randomized crossover study comparing direct inspection by light microscopy versus projected images for teaching of hematopathology to medical students.

Instruction in hematopathology at Mayo Medical School has evolved from instructor-guided direct inspection under the light microscope (laboratory method), to photomicrographs of glass slides with classroom projection (projection method). These methods have not been compared directly to date. Forty-one second-year medical students participated in this pilot study, a prospective, randomized, crossover study measuring educational performance during a hematology pathophysiology course. The students were randomized to one of two groups. All students received the same didactic lectures in the classroom and subsequent case-based review of peripheral blood smears using either laboratory or projection methods, on day one with a crossover to the other method on day two. Pre- and post-test examinations centered on morphology recognition measured educational performance on each day, followed by a questionnaire identifying the student's favored method. There was no significant difference in the pre-test and post-test scores between the two teaching methods (rank-sum P = 0.43). Students overwhelmingly preferred the projection method and perceived it as superior (76%), although post-test scores were not significantly different. Student's recommended method was split with 50% favoring the projection method, 43% favoring a combined approach, and 23% noting logistical challenges to the laboratory. In this study, the laboratory and projection method were equivalent in terms of educational performance for hematopathology among medicals students. A classroom-based approach such as the projection method is favored, given the large class sizes in undergraduate medical education, as well as the ergonomic challenges and additional resources required for large group instruction in a laboratory setting.