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Teaching to Equivalents: A New Paradigm for Resident Education in Estimation of Blood Loss

BACKGROUND: Despite its importance in clinical practice, estimation of blood loss has been consistently proven inaccurate. The aim of this study is to evaluate whether teaching to equivalents will result in more accurate estimations of blood loss. METHODS: We conducted a prospective observational study with a one-group pretest-posttest design. Fourteen stations were set up with varying amounts of simulated blood loss on common surgical items such as laparotomy pads, 4×4s, peri-pads, and floor puddles. Blood loss quantities ranged from 15 mL to 1,500 mL. All participants rotated through stations and estimated blood loss based on baseline knowledge. Following this, participants were divided into smaller groups of 3–4 each and engaged in a 10-minute teaching session. The format of the didactics incorporated principles of teaching to equivalent blood losses (ie, 100 mL is 20 4×4s, one dripping lap, 1/3 of a peri-pad). Following this, participants rotated again through each station and estimated the blood loss at each site. RESULTS: Nineteen participants (15 obstetrics and gynecology residents of varying years and four third-year medical students) participated in this study. On the pretest, the percentage correct among all participants at all stations was 12.8%. After the didactic session, the percentage correct was 45.5% (P<.05). The mean degree of error at each station was also significantly less following the intervention (108.18% compared with 32.52%, P<.05). CONCLUSION: A brief didactic session based principally on teaching to equivalents resulted in a meaningful and statistically significant improvement in estimation of blood loss.