Triploidy - variability of sonographic phenotypes.

OBJECTIVES: 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.

METHODS: 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.

RESULTS: 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.

CONCLUSIONS: 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.