The value and role of non-invasive prenatal testing in a select South African population

Abstract

Background. Concerns have been raised about the injudicious use of non-invasive prenatal testing (NIPT) using cell-free DNA (cfDNA), which often leads to inaccuracies in interpretation of the role and value of cfDNA in prenatal screening.

Objectives. To determine the value and role of NIPT in a select South African (SA) population.

Methods. A retrospective review of patients who elected to have NIPT between 1 October 2013 and 30 June 2015 at the Morningside Mediclinic Maternal and Fetal Medicine Centre in Johannesburg, SA. Patients had NIPT after either combined first-trimester screening (CFTS) or a second-trimester ultrasound scan. Data were collected on details of the first- and/or second-trimester screening, results of the NIPT, invasive tests done, decisions made in the event of abnormal results, and pregnancy outcomes.

Results. Overall, 3 473 first- and second-trimester fetal assessments were done at the centre during the study period, and 2.3% of patients (n=82) elected to have NIPT. The majority of these individuals elected to have NIPT on the basis of positive findings on CFTS, or markers of aneuploidy detected on a second-trimester ultrasound scan. Of the tests done, 97.6% produced results. Of those with no results, one did not meet quality metrics and the other had a low fetal fraction of cfDNA. There were two abnormal NIPT results, one indicating a high risk of trisomy 13 and the other a triploidy. Patients who screened negative elected not to have an invasive test.

Conclusion. The value of NIPT in this study was that it made it possible to avoid a number of invasive tests. NIPT had a role in contingency screening.