THE IMPORTANCE OF TRIPLOIDY IN PREGNANCY LOSS: A DEEP DIVE INTO A LABORATORY'S 10-YEAR EXPERIENCE.

Identification of paternal triploidy in miscarriage is important because of the risk for maternal gestational trophoblastic disease (GTD) and the need for follow-up monitoring (Seckl et al., Lancet 2010). This 10-year clinical experience reports on products of conception (POC) samples with triploidy, examining possible associations with parental origin, maternal age (MA), and gestational age (GA). Fresh POC and maternal blood samples were genotyped by a reference lab using Illumina CytoSNP-12b microarrays with bioinformatics, to rule out maternal cell contamination (MCC) and to determine parental origin of chromosome abnormalities in POC specimens. Of 63,777 samples, 8559 (13.5%) had MCC and 252 (0.4%) were inconclusive. Of 54,466 (86.1%) cases with fetal results, 3967 (7.3%) had triploidy: 2211 (55.7%) were of maternal origin and 1756 (44.3%) were of paternal origin. Of the triploidy cases, 3540 (89.2%) had an average GA of 62.7 days (range 16-273 days):3301 (93.2%) were first trimester losses, 1822 (55.2%) were of maternal origin; 1479 (44.8%) were of paternal origin; 239 (6.8%) were second/third trimester losses; 155 (64.9%) were of maternal origin; and 84 (35.1%) were of paternal origin. MA was provided for 2618 (66.0%) cases with an average age of 32.8 years (range 17.4-51 years) (Table 1). Although triploidy is usually associated with early pregnancy loss, this study identified triploid losses across a wide GA range, with∼7% of cases occurring in the second/third trimester. Previous studies have shown triploidy to be more common in younger MA patients (Maisenbacher et al., NSGC 2020). In this large cohort, we show that the percentage of paternal triploid cases was inversely related to MA.