599: Uptake of cell free fetal DNA testing in women with positive serum screening

Abstract

women with positive serum screening Shilpa Chetty, Joanne Taylor, Louanne Hudgins, Mary Norton Stanford University/Lucile Packard Children’s Hospital, Obstetrics and Gynecology, Division of Maternal Fetal Medicine, Stanford, CA, Stanford University/Lucile Packard Children’s Hospital, Department of Pediatrics, Division of Medical Genetics, Stanford, CA OBJECTIVE: To investigate how the additional option of cell free fetal DNA (cffDNA) testing impacted women’s testing choices following a positive serum screening result STUDY DESIGN: Beginning in March 2012, all women referred to our Prenatal Diagnosis Center following a positive serum screening result were offered cffDNA as an alternative to invasive prenatal diagnosis. A query of the genetic counseling database was performed to identify all such patients and to determine follow up testing decisions. Results were compared to testing decisions during the prior year (March 2011 through March 2012). Outcomes were grouped into 4 categories: 1. CVS/amniocentesis; 2. cffDNA; 3. CVS/amniocentesis and cffDNA and 4. no follow up testing. Information regarding race/ethnicity was obtained. RESULTS: Between March and June 2012, there were 113 women with positive serum screening results who were offered cffDNA testing. CVS/amniocentesis was pursued by 39% (n 44), compared to 46% (301/639) of screen positive patients the previous year (p 0.15). cffDNA was chosen by 44% (50/113). Of patients who had cffDNA testing, 2 pursued amniocentesis despite cffDNA indicating low risk result for T13, T18 or T21; both had normal karyotypes. Two patients underwent amniocentesis confirmation following cffDNA results indicated a high risk for T21; both confirmed T21. From March to June 2012, 16% (18/113) declined all testing; as compared to 53% (338/ 639) who declined follow up testing the previous year when cffDNA was not available (p 0.05). Patients that declined all testing prior to cffDNA and following introduction of cffDNA were predominantly Hispanic (56% and 62% respectively). CONCLUSION: The introduction of cffDNA testing did not result in a significant decrease in the number of women who opted for invasive testing, perhaps due to small numbers. However, fewer women declined all follow up testing when a noninvasive option was available.