Positive predictive value (PPV) of non-invasive prenatal testing (NIPT) for chromosomal abnormalities in pregnant women candidates for invasive methods

Introduction : Recently, in prenatal screening, the non-invasive method of using free fetal DNA has attracted a lot of attention. However, there is a little data on the positive predictive value (PPV) of the test. Therefore, the present study was conducted to examine the PPV of the test. Method : In this retrospective descriptive-analytical study, 104 pregnant women who voluntarily underwent Cell Free DNA Testing due to aneuploidy-based ultrasound findings, trisomy pregnancy history, abnormal results of the first or second or combined trimester screening test were included in the study. The tests were performed in a private pathobiology laboratory in Bandar Abbas between July 2016 and March 2017 . Data were collected using a standardized questionnaire and analyzed using SPSS vre. 21 software and Ki-square and independent t- tests. Results : The data obtained from the Cell Free DNA test in pregnant women showed one case of trisomy 13, three cases of trisomy 21 and one case of monosomy X. After performing the final diagnostic test using amniocentesis, the positive predictive value of the test was 100% for trisomy 13, 21 , and monosomy X. However, it was not possible to examine trisomy 18 due to the lack of cases with this abnormality in the tests. Conclusion: The findings showed high positive predictive value (PPV) of non-invasive Cell Free DNA testing for trisomy 13, 21 and monosomy X. Therefore, it seems that this test can be suggested as a non-invasive method in screening of chromosomal abnormalities in pregnant women .