Clinical Laboratory Experience With Prenatal cfDNA Screening in Triplet Pregnancies

Prenatal cfDNA screening is the most sensitive and specific screen for common aneuploidies in singleton and twin pregnancies and has been endorsed by several professional societies as a first-tier screen or contingent screen. However, data for triplet pregnancies is lacking, as these pregnancies are relatively uncommon and obtaining sufficient data for a robust analysis of test performance is challenging.

This study presents a retrospective review of over 1500 samples from triplet pregnancies screened via cfDNA for common aneuploidies.

Mean patient age was 34 years, while mean gestational age was 13 weeks. The most common indication for testing was patient age, representing > 60% of the cohort. There were 13 screen-positive cases (1.01%), 270 NR cases (17.32%), and the remainder were screen-negative. Complete or partial genetic and/or obstetric outcome information (including birth and neonatal outcomes) was available for 147 samples, including all 13 positive cfDNA samples. No false positive or false negative cases were identified.

The data from this study support the notion that cfDNA screening in triplet pregnancies is a reasonable approach given the lack of alternative screening options for these patients and that the performance likely approaches that of twin pregnancies, albeit with a higher no-call rate.