BACKGROUNDThe reports on massive transfusions (MTs) in obstetrics have recently been an increasing trend. We aimed to define the clinical features, risk factors, main causes, and outcomes of MTs due to severe postpartum hemorrhage (PPH) and the frequency trends over the past 10 years.

METHODSWe retrospectively analyzed the data of 3552 PPH patients who were at ≥28 weeks of gestation in the Obstetric Department of Peking University First Hospital from January 2006 to February 2015. The clinical records of patients receiving MT with ≥5 units (approximately 1000 ml) of red blood cells within 24 h of giving birth were included. The Pearson's Chi-square and Fisher's exact tests were used to compare the frequency distributions among the categorical variables of the clinical features.

RESULTSOne-hundred six women were identified with MT over the 10-year period. The MT percentage was stable between the first 5-year group (2006-2010) and the second 5-year group (2011-2015) (2.5‰ vs. 2.7‰, χ2 = 154.85, P = 0.25). Although uterine atony remained the main cause of MT, there was a rising trend for placental abnormalities (especially placenta accreta) in the second 5-year group compared with the first 5-year group (34% vs. 23%, χ2 = 188.26, P = 0.03). Twenty-four (23%) women underwent hysterectomy, and among all the causes of PPH, placenta accreta had the highest hysterectomy rate of 70% (17/24). No maternal death was observed.

CONCLUSIONSThere was a rising trend for placental abnormalities underlying the stable incidence of MT in the PPH cases. Placenta accreta accounted for the highest risk of hysterectomy. It is reasonable to have appropriate blood transfusion backup for high-risk patients, especially those with placenta accreta.