Thesis

NIPT in a clinical setting: patient decisions and pregnancy outcomes

Noninvasive prenatal testing (NIPT) has recently become clinically available for screening of fetal trisomies, creating an alternative to California State Prenatal Screening (CaPNS) as well as prenatal diagnostic tests. The study sought to investigate how NIPT functions in an HMO setting by focusing on women who were eligible for NIPT based on a positive CaPNS result in the Kaiser Northern California system. Study objectives included identifying the detection rate of screened trisomies, looking at the choice of NIPT based on various factors, and evaluating the use of NIPT as a second-tier test. Retrospective review was conducted for 811 pregnancies eligible for NIPT. After receiving a positive CaPNS result, 57.3% of patients chose NIPT as a follow-up test. There were no false-positives or false-negatives detected in this population. Women who received a trisomy 21 CaPNS positive result were significantly more likely to choose NIPT if they received their CaPNS result in the first trimester as opposed to the second. CaPNS risk score was not associated with test choice. A trend that women of Hispanic ancestry were slightly less likely to choose NIPT was observed. The presence of ultrasound findings and maternal age were also associated with choice of NIPT. Pregnancies with at least one ultrasound abnormality were more often associated with diagnostic testing rather than NIPT, and women age 40 and above were more likely to choose NIPT than women less than 40. Use of NIPT as a second-tier test was associated with a significantly longer test course than going straight from NIPT to diagnostic testing.

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