To study the clinical characteristics, the outcome of pregnancy and the risk factors of uteroplacental apoplexy complicating severe placental abruption. A retrospectively study of the 52 cases of placental abruption who had delivered in our hospital from Jan. 2002 to Dec. 2006 was conducted. These cases were divided into 2 groups: 17 cases of uteroplacental apoplexy complicating placental abruption as observation group, the others with no uteroplacental apoplexy as control group. The risk factors of disease, clinical characteristics and the outcome of pregnancy between the two groups were compared. (1) The incidence of placental abruption was 0.15% (52/35 049) among the total deliveries patients with uteroplacental apoplexy complicating placental abruption took up 0.05% (17/35 049) of all deliveries and 33% (17/52) of all abruption cases. (2) General information and delivery: There were no significant differences (P > 0.05) regarding their mean age and BMI in two groups. All women in observation group had C-section delivery, which were 21 in control group. 14 women had vaginal delivery. The incidence of premature labour was 88% (15/17) in observation group, and 49% (17/35) women in control group delivered after 37 weeks. Significant differences were observed regarding delivery methods and gestational weeks (P < 0.01). (3) RISK FACTORS: the incidence of preeclampsia, 71% (12/17), and the duration of disease, 6.4 hours, in observation group were more than those in control group, 20% (7/35) and 4.2 hours (P < 0.01). There were no significant differences between two groups in premature rupture, polyhydroamnions (P > 0.05). (4) Clinical characteristics in two groups: bloody amniotic fluid, fetal distress, hematometra and postpartum hemorrhage occurred in 82% (14/17) vs 26% (9/35), 65% (11/17) vs 29% (10/35), 35% (6/17) vs 6% (2/35), and 59% (10/17) vs 11% (4/35), with a significant difference (P < 0.01), but no statistical difference existed between indices such as abdominal pain, vaginal bleeding and abdominal tension (P > 0.05). (5) Placenta sites and abruption areas: placenta sites were distributed from anterior or posterior of uterine body 5/17 vs 24/35, the fundus or cornu of uterus 12/17 vs 11/35 (P < 0.01). All cases in observation group presented abruption areas > 1/3, and 9 cases >or= 2/3, 27 cases abruption areas < 1/3 and 8 cases abruption areas 1/3 - 2/3 in control group (P < 0.01). (6) Other complications and outcome: Hemorrhagic shock 3 vs 0, DIC 3 vs 0, hysterectomy 1 vs 0, intrauterine fetal death 3 vs 2, neonatal asphyxia 8 vs 5 and neonatal death 1 vs 0. There were significant differences (P < 0.01) between the two groups. Preeclampsia, long duration of disease and fundal or cornual placenta a risk factors for uteroplacental apoplexy complicating placental abruption, which may lead to a poor maternal-fetal prognosis.