Author

Olivia Kesler

Date of Award

Spring 2020

Document Type

Open Access Thesis

Department

Genetic Counseling

First Advisor

Jessica Fairey

Abstract

Non-invasive prenatal screening (NIPS) has rapidly grown in uptake since its introduction to clinical practice in 2011. In contrast to more traditional methods of screening, NIPS is the first to utilize cell-free fetal DNA for risk assessment of chromosomal aneuploidy and other conditions. Clinical validity has been established for the most common autosomal aneuploidies (Trisomy 21, Trisomy 18, and Trisomy 13) and sex chromosome aneuploidies, though some laboratories screen for conditions beyond these. A screen positive does not always indicate a true positive, therefore professional guidelines recommend diagnostic testing for confirmation and informed decision making on pregnancy management. Furthermore, the methodology of NIPS means a positive result could be maternal or placental in origin and not necessarily represent the fetus. It is also possible to get a no call result that could suggest another genetic aberration, at which point patients and providers are left to follow up at their own discretion due to the lack of management guidelines. The goal of our study was to track pregnancy outcomes for patients receiving abnormal NIPS results, and use those outcomes to develop follow-up protocol for our practice. Additionally, we sought to make novel correlations for no call results. One hundred eighty one women were eligible for inclusion after medical record review. Consistent with other research, the greatest number of true positives were for autosomal aneuploidies. Patients’ uptake of diagnostic testing was impacted by the individual result type, presence of ultrasound abnormalities, and laboratories’ indications of a maternal or fetal abnormality. During the course of our study, some laboratories began specifying reasons for no calls. This was helpful in guiding management, as certain types of no calls were more strongly associated with abnormalities and/or adverse fetal outcomes. Several no call results in our study led to the identification of genetic aberrations in both fetuses and mothers, suggesting the importance of follow-up and appropriate management. Overall, our study reiterates the importance of diagnostic testing as confirmation for screen positives, contributes outcome data to the growing incidence of abnormal NIPS results, and provides follow-up recommendations based on each result type.

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