Cerebroplacental blood flow redistribution in monochorionic-diamniotic twin pregnancies with selective fetal growth restriction

Objective To analyze the cerebroplacental blood flow distribution characteristics in monochorionic-diamniotic (MCDA) twin pregnancies with selective fetal growth restriction (sFGR), and investigate the relationship between co-twin cerebroplacental blood flow discordances and co-twin birth weight discordances (BWdisc). Methods The cerebroplacental blood flow distribution characteristics and their discordances were analyzed retrospectively in 52 MCDA twin pregnancies with normal growth (control group) and 52 with sFGR (case group), including the umbilical artery pulsatility index (UA-PI), middle cerebral artery peak systolic velocity (MCA-PSV), middle cerebral artery pulsatility index (MCA-PI), cerebroplacental ratio (CPR), and their discordances (UA-PIdisc, MCA-PSVdisc, MCA-PIdisc and CPRdisc). Results Compared to the control group, UA-PIdisc, MCA-PIdisc and CPRdisc increased significantly (all P<0.01). UA-PIdisc, MCA-PIdisc and CPRdisc were related positively to BWdisc as shown by correlation analyses (r=0.488, 0.414, 0.592; all P<0.001), and they had moderate predictive accuracy for sFGR with area under the curves of 0.743, 0.662 and 0.778, with sensitivity of 48.08%, 67.31% and 71.15%, and specificity of 92.31%, 59.62% and 78.85% (all P<0.01). Multivariate Logistic regression analyses showed that only CPRdisc were independently associated with sFGR (P<0.05). Conclusions More cerebroplacental blood flow discordances are observed in MCDA twin pregnancies with sFGR. Co-twin cerebroplacental blood flow discordance is related to BWdisc. Key words: Ultrasonography; Monochorionic-diamniotic twin; Selective growth restriction; Cerebroplacental ratio