Non-invasive pre-natal testing vs amniocentesis and karyotyping: A David vs Goliath story

Introduction: Chromosomal anomalies constitute a potentially burdening and distressing group of illnesses which if screened/diagnosed in time can offer respite to the expectant family. Currently detection is based on a host of screening tests followed by Chorionic villous sampling or amniocentesis which are invasive procedures associated with a mild risk of pregnancy loss and have a long turnaround time. Non-invasive pre-natal testing uses sensitive and specific techniques to overcome the issue and has the potential to replace the conventional diagnostic tests. Materials and Methods: A total of 700 consecutive Ante natal cases reporting to Gynaecology OPD in two centres over a duration of two years were screened using protocols applicable as per gestational age. 39 screen positive high risk positive cases were further subjected to NIPT and CVS/amniocentesis and the detection rates compared. Results: In the primary outcome it was found that the detection rates were comparable with NIPT and conventional diagnostic tests and both showed equivocal results. Conclusion: The study suggests no significant difference in the detection rates on NIPT vs the conventional karyotype. However, the results need to be interpreted in the light of low incidence rates of chromosomal anomalies in general population. While a universal application of the test is desirable cost factor needs to be permissive for it to be beneficial in a holistic manner.