The accuracy of blood. loss estimation after simulated vaginal delivery

BACKGROUND: Visual blood loss estimation often underestimates blood loss. In this study we sought to determine the effect of calibrated drape markings on blood loss estimation in a simulated vaginal delivery. METHODS: Subjects were randomized to estimate simulated blood loss (300, 500, 1000, and 2000 mL) in calibrated or noncalibrated vaginal delivery drapes and then crossover. RESULTS: Visual blood loss estimation with noncalibrated drapes underestimated blood loss, with worsening accuracy at larger volumes (16% error at 300 mL to 41% at 2000 mL). The calibrated drape error was < 15% at all volumes. CONCLUSIONS: Calibrated vaginal delivery drapes improve blood loss estimation.