Risk factors for massive postpartum bleeding in pregnancies in which incomplete placenta previa are located on the posterior uterine wall

OBJECTIVE: To identify factors associated with massive postpartum bleeding in pregnancies complicated by incomplete placenta previa located on the posterior uterine wall. METHODS: A retrospective case-control study was performed. We identified 210 healthy singleton pregnancies with incomplete placenta previa located on the posterior uterine wall, who underwent elective or emergency cesarean section after 24 weeks of gestation between January 2006 and April 2016. The cases with intraoperative blood loss (≥2,000 mL) or transfusion of packed red blood cells (≥4) or uterine artery embolization or hysterectomy were defined as massive bleeding. RESULTS: Twenty-three women experienced postpartum profuse bleeding (11.0%). After multivariable analysis, 4 variables were associated with massive postpartum hemorrhage (PPH): experience of 2 or more prior uterine curettage (adjusted odds ratio [aOR], 4.47; 95% confidence interval [CI], 1.29 to 15.48; P=0.018), short cervical length before delivery (<2.0 cm) (aOR, 7.13; 95% CI, 1.01 to 50.25; P=0.049), fetal non-cephalic presentation (aOR, 12.48; 95% CI, 1.29 to 121.24; P=0.030), and uteroplacental hypervascularity (aOR, 6.23; 95% CI, 2.30 to 8.83; P=0.001). CONCLUSION: This is the first study of cases with incomplete placenta previa located on the posterior uterine wall, which were complicated by massive PPH. Our findings might be helpful to guide obstetric management and provide useful information for prediction of massive PPH in pregnancies with incomplete placenta previa located on the posterior uterine wall.