Invasive Prenatal Diagnosis After Positive Cell-Free Fetal DNA Compared With Sequential Prenatal Screening

Abstract

INTRODUCTION: The use of circulating cell-free nucleic acid for prenatal aneuploidy screening has been rapidly accepted by patients and clinicians. We sought to compare decisions after a positive sequential screen and circulating cell-free nucleic acid assay. METHODS: We reviewed results from sequential screening and circulating cell-free nucleic acid analyses in this retrospective study performed at Northwestern University between June 1, 2012, and May 31, 2013. Inclusion criteria were: initial aneuploidy screening before 14 weeks of gestation and screen-positive results for either sequential screening or cell-free nucleic acid assay testing. Only women at increased risk for fetal aneuploidy were offered circulating cell-free nucleic acid screening. Exclusion criteria were multifetal pregnancy, screening after 14 weeks of gestation, and in vitro fertilization, or donor gamete pregnancy. All women received genetic counseling before screening. RESULTS: Sixty-seven women were evaluated. Fifty were positive for the sequential screen; 22 (44%) chose to undergo circulating cell-free nucleic acid screening, whereas 22 (44%) elected invasive prenatal diagnosis. The other six (12%) elected no further evaluation. Twenty of these 22 women who chose circulating cell-free nucleic acid testing after sequential were screen-negative and elected no further evaluation. Seventeen women were initially screen-positive for circulating cell-free nucleic acid screening; 15 (88%) underwent invasive testing, whereas two (12%) reported spontaneous abortion. CONCLUSIONS: Women with a positive sequential screen were far less likely to undergo invasive testing than those with a positive circulating cell-free nucleic acid result. Possible explanations include differences in aneuploidy risk in the two cohorts, fear of invasive testing resulting in pain or loss of pregnancy and thus chosen only when fetal aneuploidy seemed inevitable, and availability of circulating cell-free nucleic acid to evaluate positive sequential outcomes.