LAUSR

OBJECTIVE In a 2015 Maternal-Fetal Medicine Units (MFMU) Network study, only half of Placenta Accreta Spectrum (PAS) cases were suspected before delivery and the outcomes in the anticipated cases were paradoxically poorer than in unanticipated PAS cases. This was possibly because the antenatally suspected cases were of greater severity. We sought to compare the outcomes of expected vs unexpected PAS in a single large U.S. center with multidisciplinary management protocol. METHODS Retrospective cohort study carried out between January 1, 2011 and June 30, 2018 of all histology-proven PAS deliveries in an academic referral center. Patients diagnosed at the time of delivery were cases (unexpected PAS = uPAS), and those who were antentally diagnosed were controls (expected PAS = ePAS). The primary and secondary outcomes were the estimated blood loss (EBL) and the number of red blood cell (RBC) units transfused, respectively. Variables are reported as median and interquartile range (IQR) or number (%). Analyses were made using appropriate parametric and non-parametric tests. RESULTS Fifty four of the 243 patients (22.2%) were in the uPAS group. Patients in the ePAS group had a higher rate of previous cesarean delivery [170/189 (89.9%) vs. 35/54 (64.8%); p<0.001] and placenta previa [135 (74.6%) vs. 19 (37.3%); p<0.001]. There was a higher proportion of increta/ percreta in ePAS vs. uPAS [125 (66.1%) vs. 9 (16.7%), p<0.001]. Both primary outcomes were higher in the uPAS group [EBL: 2.4L (1.4-3) vs. 1.7L (1.2-3), p=0.04; RBC Units: 4 [1-6] vs. 2 [0-5], p=0.03]. CONCLUSIONS Our data contradict the MFMU results, and instead show better outcomes in the expected PAS group, despite a high proportion of women with more severe placental invasion. We attribute this to our multidisciplinary approach and ongoing process improvement in the management of expected cases. The presence of an experienced team appears to be a more important determinant of maternal morbidity in PAS than the depth of placental invasion.