Triploidy - variability of sonographic phenotypes

To analyze sonographic abnormalities in triploid pregnancies and assess the usefulness of the classification proposed by McFadden and Kalousek for prenatal sonographic assessment of triploid fetuses.

We conducted a retrospective analysis of the sonographic features in a series of 67 triploid fetuses evaluated between 11 and 30 weeks of gestation in a single referral center between 1997 and 2015.

Non-specific structural fetal defects were visualized in the majority of fetuses (61.2%) regardless of the parental origin of the triploidy. A 'diandric phenotype' was identified in eight relatively well-grown fetuses (11.9%) that presented with cystic placentas. A 'digynic phenotype' was identified in 47 asymmetrically growth-restricted fetuses with non-cystic placentas (70.2%). In 12 cases (17.9%), features of both phenotypes were present.

Nearly 40% of triploid fetuses do not have any apparent structural abnormalities, and only careful assessment of fetal growth and placenta may lead to the suspicion of the diagnosis. As diandric triploidy carry a high risk for maternal complications, identification of these cases is vital for prenatal counseling. In nearly 20% of triploid pregnancies, parental origin cannot be established based on sonographic assessment. © 2017 John Wiley & Sons, Ltd.