Diagnostic Testing Uptake After High-Risk cffDNA Screening [6B

Abstract

INTRODUCTION: Introduction of cffDNA screening has decreased the rate of diagnostic testing and serum screening. We hypothesized that the uptake of diagnostic testing after abnormal cffDNA depends on the type of chromosomal aneuploidy suspected. Our aim was to evaluate the uptake of diagnostic testing in women with abnormal cffDNA screening. METHODS: A retrospective study of singleton gestations and any abnormal cffDNA results between 10/1/2012 and 3/31/2016. We compared 3 cohorts based on high-risk cffDNA results for (1) trisomies 21, 18, 13, (2) sex chromosome aneuploidies (SCA) and (3) other (no call, unreportable). Diagnostic testing was offered to all study subjects. Primary outcome was uptake of diagnostic testing by abnormal cffDNA results. P-value < .05 was considered significant. RESULTS: 443 women met inclusion criteria. Mean age, rate of AMA and abnormal ultrasound were higher in trisomy group compared to SCA and other category. Uptake of diagnostic testing after a positive cffDNA result in this cohort was 31.6%. Women at high-risk cffDNA for trisomies were more likely to undergo diagnostic testing compared to SCA or other category (P=.02). Similarly, women with high-risk cffDNA for trisomies were more likely to be confirmed with diagnostic testing compared to SCA and other category (P < .0001). Diagnostic testing results in the last group were more likely to be normal or discordant from screen result. CONCLUSION: Diagnostic testing uptake is low overall but is higher in women with cffDNA screening results indicating high-risk for trisomy compared to sex chromosome aneuploidies or other category. High-risk screens for trisomies are more likely to be confirmed.