A Retrospective Single-center Analysis of Prenatal Diagnosis and Follow-up of 626 Chinese Patients with Positive Non-invasive Prenatal Testing Results

Abstract Background: This study explores the diagnostic efficiency of different prenatal diagnostic approaches for women with positive non-invasive prenatal testing (NIPT) results by analyzing their clinical information and pregnancy outcome. Methods: We collected data on 626 NIPT-positive pregnant women from January 2017 to June 2021 and arranged subsequent prenatal diagnostic operations for them after genetic counseling, along with long-term intensive follow-up. A total of 567 women accepted invasive prenatal diagnosis (IPD) (90.57%), and 262 cases were confirmed as true positives of NIPT. Results: The positive predictive value for trisomy 21 (T21), trisomy 18 (T18), trisomy 13 (T13), sex chromosome aneuploidies (SCAs), rare autosomal trisomies (RATs), and microdeletion and microduplication syndromes (MMS) were 81.13%, 37.93%, 18.42%, 48.83%, 18.37%, and 41.67%, respectively. Discordant results between NIPT and IPD were seen in 53 cases, with the discordance rate being 9.35%. Additionally, there were 43 cases with discordant results between karyotyping and chromosomal microarray analysis (CMA)/copy number variation sequencing. Conclusions: Additional reporting of RATs and MMS with routine NIPT that only detects T21/T18/T13 and SCAs can yield diagnosis more accurately. However, NIPT cannot be used as a substitute for IPD owing to its high false positive rate and discordances with other diagnostic methods. We recommend CMA combined with karyotyping as the preferred method for accurate diagnosis of NIPT-positive women.