Placenta accreta spectrum disorder (PASD) and placenta previa (PP) are two of the most hideous obstetric complications which are usually associated with a history of cesarean section (CS).Moreover,women with PASD,PP and/or a cesarean scarred uterus are more likely to have adverse pregnancy outcomes,including blood transfusion,hysterectomy,pelvic organs damage,postpartum hemorrhage,disseminated intravascular coagulation,multi-organ dysfunction syndrome and even maternal or fetal death.This study aimed to investigate the efficacy of precesarean internal iliac artery balloon catheterization (BC) for managing severe hemorrhage caused by PASD and PP with a history of CS.This participant-assigned interventional study was conducted in Tongji Hospital.We recruited 128 women with suspected PASD,PP and a history of CS.Women in the BC group accepted precesarean BC of bilateral internal iliac arteries before the scheduled cesarean delivery.Women in the control group underwent a conventional cesarean delivery.Intraoperative hemorrhage,transfusion volume,radiation dose,exposure time,complications and neonatal outcomes were discussed.There were significant differences in calculated blood loss (CBL) between BC group and control group (1015.0±144.9 vs.1467.0±171.0 mL,P=0.04).Precesarean BC could reduce intraoperative red blood cell (RBC) transfusion as compared with control group (799.5±136.1 vs.1286.0±161.6 mL,P=0.02) and lessen the rate of using blood products (57.1％ vs.76.4％,P=0.02).The incidence of hysterectomy was also lower in BC group than in control group.Postpartum outcomes showed no significant differences between the two groups,except that postoperation hospitalization was longer in BC group than in control group (6.7±0.4 vs.5.8±0.2 days,P=0.03).Precesarean BC of internal iliac artery is an effective method for managing severe hemorrhage caused by PASD and PP with a cesarean scarred uterus,as it could reduce intraoperative blood loss,lessen intraoperative RBC transfusions and potentially decrease hysterectomies.