Risk Factors for Postpartum Hemorrhage Due to Uterine Atony
Abstract Number: 271
Abstract Type: Original Research
Background: Postpartum hemorrhage due to uterine atony (PPHUA) is a leading cause of maternal morbidity and mortality. Because the incidence of severe PPHUA at our hospital seemed high, we performed a case-control study of PPHUA to determine risk factors and look for ways to improve clinical care.
Methods: Following IRB approval, we retrospectively reviewed a consecutive series of 123 patients diagnosed with PPHUA from 2006-2007. Inclusion criteria included a discharge diagnosis of PPH, blood loss >500 mL greater than anticipated for the route of delivery, and the use of drugs to increase uterine tone (methergine, prostaglandins, or high-dose oxytocin). The next two patients delivering by the same route served as control patients. Information regarding parity, gestational age of infants, singleton or twin gestation, race, incidence of maternal hypertension or gestational diabetes, presence of chorioamnionitis, magnesium use, oxytocin use, and duration of oxytocin use was recorded for all subjects in each group. In the PPHUA group, information regarding time from delivery to recognition of uterine atony, whether oxytocin was infusing when uterine atony was recognized, and number of units of packed red blood cells transfused was collected. Data are reported as mean and standard deviation or as a percentile for comparison.
Results: PPHUA (n=123) and control (n=246) groups differed in percent of patients with postpartum magnesium infusion (27% vs. 5%), percent of patients with hypertension (26% vs. 15%), percent Hispanic ethnicity (14% vs. 6%), percent grand multiparous patients (parity > 4; 6% vs. 2%), and percent multiple gestation (8% vs. 4%). Hemorrhage occurred 2.5 +/- 2.8 hours after delivery. Oxytocin was infusing in 40% of PPHUA patients at the time atony was diagnosed. Among the PPHUA patients, 56% of those receiving magnesium were not receiving oxytocin at the time of diagnosis.
Discussion: Obstetric, medical, and ethnic factors can identify patients at higher than normal risk for PPHUA. We are using this data to develop protocols to prevent PPHUA in high-risk patients.