Variation in inferior vena cava diameter as an early marker in postpartum hemorrhage.

Objective To examine the association between IVC diameter and postpartum blood loss and whether the variations in IVC diameter, if present, stands as a useful marker in diagnosis of postpartum blood loss. Materials and methods Prospective case control study was conducted in a University Teaching Medical Center in Afula, Israel, between November, 2018 and March, 2020. The study cohort consisted of women with singleton pregnancy that delivered vaginally at term. The study group included women with a visually estimated blood loss of 1000ml or more at time of enrollment. Hemodynamically unstable women or women with major bleeding at time of diagnosis were not included. The control group consisted of women with uneventful fourth stage of labor. IVC diameters were measured by the use of abdominal ultrasonography during inspiration (IVCi) and expiration (IVCe) and the collapsibility index (CI) was then calculated (IVC e-i/IVC e). The primary outcome was the proportion of variation in IVC diameters between the study group and the control group. In order to demonstrate a difference of 20%, 108 women at a ratio of 1:2, for the study and control groups respectively, were needed to achieve a power of 80% with alpha of 0.05. Results Overall, 36 and 72 women were included in the final analysis in the study and control groups respectively. The IVCi and IVCe diameters were significantly smaller in the study group (0.93±0.30 cm and 1.26±0.32 cm respectively) compared to the control group (1.42±0.31 and 1.75±0.28 cm respectively), p=0.001. The reductions in IVCi and IVCe diameters in the study group were 35.0% and 28.0% respectively. CI in the study group increased significantly by 42.9% [from 18.15 (±5.07) to 26.04 (±8.67), p=0.001]. The CI was a significant predictor that correctly predicted about 81% of women who required blood transfusion. Conclusions IVC diameters change in response to postpartum blood loss. Measurement of IVC diameters is an objective and useful method for the diagnosis of blood loss and prediction of cases that might require blood transfusion. This article is protected by copyright. All rights reserved.