BACKGROUND Postpartum hemorrhage (PPH) is a major obstetric complication, and the real-time measurement of blood loss is important in the management and treatment of PPH. We designed a new two-set liquid collection bag (TSLCB) for measuring postpartum blood loss in vaginal delivery. The aim of this study was to evaluate the effectiveness of the TSLCB in separating the blood from
the amniotic fluid during vaginal delivery and in determining the accuracy of the measured postpartum blood loss. METHODS A prospective, randomized, case control study was conducted in the Women's Hospital, Zhejiang University School of Medicine, from March 2018 to April 2018. Sixty single pregnant women with spontaneous labor at 37-41 weeks without maternal complications were randomly divided into the experimental and control groups. The TSLCB was used to evaluate separately the amount of blood and amniotic fluid. For the control group, visual estimation and traditional plastic blood-collecting consumables were used to estimate the amount of postpartum blood loss. The measured blood loss between the two groups was compared, and the association of the measured blood loss with various clinical lab indices and vital signs was investigated. RESULTS The TSLCB (the experimental group) improved the detection of the measured blood loss compared with visual estimation and the traditional method (the control group) (P < .05). In the experimental group, correlation analysis showed that the measured blood loss at delivery and within 24 h of delivery was significantly associated with the decreased hemoglobin level, red blood cell count, and hematocrit level of patients (r = -0.574, -0.455, -0.437; r = 0.-595, -0.368, -0.374; P < .05). In the control group, only the measured blood loss within 24 h of delivery was associated with the decreased hemoglobin level (r = -0.395, P < .05). No blood transfusion and plasma expanders were required in the treatment of PPH for both groups. CONCLUSIONS The TSLCB can be used to accurately measure the postpartum blood loss in vaginal delivery by medical personnel.