Single-nucleotide polymorphism microarray detects molar pregnancies in 3% of miscarriages.

OBJECTIVE

To determine the frequency of molar pregnancy in miscarriage cases based on single-nucleotide polymorphism (SNP) microarray testing on products of conception (POC) tissue and to estimate the sensitivity of ultrasound and histopathologic evaluation for cases identified to be at risk for gestational trophoblastic disease.

DESIGN

Retrospective cohort analysis.

SETTING

Reference laboratory.

PATIENT(S): POC specimens from 26,101 consecutive miscarriages.

INTERVENTION(S): POC samples were sent to a single laboratory for analysis. Maternal age, gestational age, egg donor use, indication for testing, and additional clinical information were obtained from the requisition form and a survey sent to ordering providers.

MAIN OUTCOME MEASURE(S): Rates of full paternal uniparental disomy (UPD), indicative of complete molar pregnancy, and triploidy of paternal origin, indicative of partial molar pregnancy, in POC samples.

RESULT(S): Paternal triploidy was detected in 638 cases (2.8%) and full paternal UPD in 72 cases (0.3%). Of the cases with complete clinical information (224/710; 31.5%), histopathology and/or ultrasound did not detect 71% of partial molar pregnancies and 30% of complete molar pregnancies.

CONCLUSION(S): Molar pregnancy, detected in 3.1% of all miscarriages in this study with the use of 24-chromosome SNP microarray testing, occurred significantly more frequently than previously estimated with the use of ultrasound and/or histopathology.