Effects of Anemia Treatment on the Accuracy of Measured Blood Loss in Pregnant Women Undergoing Cesarean Delivery: A Retrospective Study

Context: There is no gold standard method for quantifying the volume of blood loss in surgical settings. Aims: To investigate the effects of anemia treatment on the differences between measured blood loss (MBL) and calculated blood loss (CBL) in pregnant women who underwent cesarean delivery, considering the nonlinear association between body mass and estimated circulating blood volume. Settings and Design: Single-center retrospective study. Methods and Material: Patients aged ≥20 years who underwent cesarean delivery under spinal anesthesia and had hematocrit data measured within 1 month from the date of surgery and postoperative day 1 were included. MBL is the sum of intraoperative and postoperative blood loss. CBL was calculated as follows: estimated circulating blood volume * (preoperative hematocrit–postoperative hematocrit)/preoperative hematocrit. The estimated circulating blood volume was corrected using the body mass index. Our primary outcome was the correlation coefficient between MBL and CBL between pregnant women with and without anemia treatment. Statistical Analysis Used: Fisher’s method and t -test. Results: Of the 989 pregnant women included in the final analysis, 18.9% received iron treatment for anemia before cesarean delivery. A statistically significant but weak correlation was found between MBL and CBL in both pregnant women without anemia treatment (r = 0.37, P < 0.001) and those with anemia treatment (r = 0.28, P < 0.001). However, these correlation coefficients were not statistically significant ( P = 0.25). Conclusions: There was no statistical difference in the correlation between MBL and CBL based on whether anemia was treated before cesarean delivery.