The Accuracy of Blood Loss Estimation After Simulated Vaginal Delivery

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. Subjects were randomized to estimate simulated blood loss (300, 500, 1000, and 2000 mL) in calibrated or noncalibrated vaginal delivery drapes and then crossover. 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