885 Outcomes in Monochorionic Diamniotic Pregnancies with Proximate Placental Cord Insertions

To evaluate outcomes in monochorionic diamniotic (MCDA) pregnancies with proximate placental cord insertions (pPCI). Single center retrospective analysis of MCDA pregnancies between 2014-2022. Distance between placental cord insertions (PCI) was defined by ultrasound examination. Outcomes of pregnancies with pPCI (≤ 4 cm) were compared to those with intermediate PCI or iPCI (4.1-6.0 cm) from the same study period. For each pPCI pregnancy, 2 controls with PCI distance > 6 cm (normal or nPCI) were selected after matching for the diagnosis and the type of intervention. 60 pregnancies with pPCI and 46 with iPCI were evaluated. More than 90% of pregnancies were twins in both groups. The rate of pathologies related to monochorionic placentation like TTTS was similar between groups. There was a non-significant trend towards a greater number of type III sFGR cases in the pPCI group (37% vs 22%). The rate of intervention was similar in both groups, though there were a smaller number of cases that underwent laser in the pPCI group (3.3% vs 10.8%). The intertwin estimated fetal weight (EFW) discordance was lower in the pPCI group (18% vs 22%, p=0.04). Upon comparing pPCI and nPCI group, the rate of intervention was similar though the percentage of cases undergoing laser were greater in the nPCI group (3.3% vs 14.2%, p=0.04). A greater number of cases were managed with “amnioreduction (AR) only” in the pPCI group (8.3 vs 1.7, p=0.04). The EFW discordance was considerably lower in the pPCI group (18% vs 26%, p< 0.0001) though perinatal outcomes were similar in both groups. Linear regression model included all patients (n=226) and the distance between PCI significantly influenced EFW discordance after controlling for sFGR and gestational age at initial evaluation. Presence of pPCI was associated with lower EFW discordance likely due to even distribution of placental share. Lower rates of laser and higher rates of AR management in this group suggests technical challenges associated with laser though the overall outcomes are comparable likely driven by the underlying diagnosis.