EP16.09: Cerebroplacental ratio at term and risk of adverse perinatal outcome

Abstract

To determine the performance of cerebroplacental ratio and its association with adverse perinatal outcome (APO) in pregnancies explored at late third trimester. A retrospective cohort of low risk singleton pregnancies scanned at 37 gestational weeks was reviewed. At inclusion, biometry for estimated fetal weight (EFW) and feto-placental Doppler evaluation (uterine artery pulsatility index [UtA-PI], cerebroplacental ratio [CPR] normalised by EFW according to Baschat were measured. APO was defined as the occurrence of composite morbidity including birthweight below 5th centile, emergent Caesarean section for non-reassuring fetal status, 5-min Apgar score <7 or neonatal acidosis at birth defined by ph venous below 7.1, admission at NICU and stillbirth. A total of 2272 pregnancies were included. Among these, 65.2% were nulliparous and 34.8% were multiparous. Overall with the definition of APO including SGA 5 centile the total number of APO was 659 (29%). The cerebroplacental ratio below 5th centile according to Baschat was present in a 13.1% of cases. Out of those 47% of APO were in the group with low CPR (<5th centile) rendering an odds ratio of 2,54 (1,98-3,26). The low CPR was also a risk factor for the individual components of the adverse outcome, especially mortality and transfer to NICU. Comparing the CPR according to Estimated Fetal Weight the cpr remained significantly associated with APO, even in the cases of normal estimated fetal weight the odds ratio for adverse outcome with low CPR was 1,58 (1.02-2.44). 11.4 % of the adverse outcome is in the group of normal growth but low CPR. The low Cerebroplacental Ratio has become a proxy of abnormal perinatal outcome when determined in the late third trimester, even in cases with normal growth we have found a significant association with adverse perinatal outcome. There are clear limitations because of the retrospective review and the selection of cases, nevertheless the abnormal ratio seems to be related with an increased risk of abnormal outcome.