In this blog, Dr Sabrina S. A. Achim, MD, discusses her research into the impact of NIPT on Fetal Anomaly Screening since its introduction into the NHS.
As a junior doctor, managing my daily workload alongside my training portfolio requirements can be a daunting experience. So, when filling the portfolio ‘tick box exercise’ as a foundation year two (FY2) in obstetrics and gynaecology, it was a happy coincidence that I had the opportunity to do something I care deeply about; empowering women by giving them choices.
After discussion with consultants and midwives about the latest addition to the prenatal screening pathway, the introduction of non-invasive prenatal testing (NIPT) in NHS England, we set to find out how the preferences of pregnant women for antenatal testing have changed. We did this by exploring the impact of the implementation of NHS NIPT in England on women with initial higher chance screening results, visiting antenatal clinic at Hull Royal Infirmary (HRI) between April 2018 and March 2022. I am grateful to the following people for helping me make this project a possibility: Jill Atkinson, Vicky Jennings, Dr. Uma Rajesh.
NIPT involves a simple blood test which uses cell-free DNA in the maternal bloodstream to screen for fetal aneuploidy (an abnormal number of chromosomes). NIPT was first introduced into clinical practice in 2011 (1). Since June 2021 it has been incorporated into the existing NHS England antenatal screening pathway for Down’s, Edwards’ and Patau’s syndromes (2). In the post COVID-19 world, NIPT is on the way to becoming an increasingly common screening option in antenatal care and healthcare (3).
The main advantage of NIPT as a screening test is giving women the choice of finding out more about their unborn baby before an invasive procedure takes place. This was reflected in our results when looking at the impact of NHS NIPT on women’s preferences at HRI. Prior to incorporation of NIPT into the NHS screening pathway, the financial cost and private nature of NIPT was a barrier for many women. We found that many women with a higher chance result on their combined/quadruple screen test who would have declined invasive testing are now opting for NIPT. About 39% of women declined invasive testing and privately funded NIPT before NHS England funded NIPT – this has reduced to a mere 5% since June 2021, with an 86% uptake of NIPT without any change in pregnancy outcomes.
Pregnant women carrying one baby, or twins, have the option to undergo the combined or quadruple screening test between 10-14 weeks or up to 20 weeks, respectively. They also have the choice to screen for Down’s syndrome only, Edwards’ syndrome and Patau’s syndrome only, or all three conditions. Since June 2021, women in England with a higher chance result on the initial screening can access a second screening test (NIPT), proceed to invasive diagnostic testing (amniocentesis or chorionic villus sampling) or not have any further test at all.
Cell-free DNA testing for fetal karyotyping is a relatively new technology, with the same resistance and controversies that any new technology would face. Last year in the United States, the US Food and Drug Administration (FDA) had to issue a warning regarding misinterpretation of NIPT results by providers that marketed it as a “laboratory developed test” to bypass the need for an FDA review and approval. The Medicines and Healthcare products Regulatory Agency (MHRA) in the UK stated that it had not found any issues with the NIPT accessible within the UK health sector (4). Much of the issues surrounding NIPT relate to the implications of a positive result.
Gil et al reported NIPT to have a pooled detection rate of 99.2% and a false-positive rate of 0.09% of for the three conditions mentioned above in singleton pregnancies (5). It is crucial for us as healthcare practitioners to communicate the nature of NIPT as a screening test only, therefore a “higher chance” NIPT result is not diagnostic of chromosomal aneuploidy. The latter can only be done through chorionic villus sampling (CVS) or amniocentesis. Nevertheless, the limitations of NIPT as a screening test is often more palatable than the risk of miscarriage associated with invasive diagnostic testing.
I believe with continuous education and engagement with women on their antenatal journey, we would be able to equip them with the information they need to make informed decisions. Pregnancy can be filled with excitement and uncertainties; providing options and having an open discussion about NIPT can pave the way to change those uncertainties into expectations and preparations.
References
- Chandrasekharan S, Minear MA, Hung A, Allyse M. Noninvasive prenatal testing goes global. Sci Transl Med. 2014 Apr 9;6(231):231fs15. doi: 10.1126/scitranslmed.3008704. PMID: 24718856; PMCID: PMC4112725
- Permalloo, N. (2021) NIPT rolls out to all areas of England as part of the existing NHS screening pathway for Down’s syndrome, Edwards’ syndrome and Patau’s syndrome. Public Health England . Available at: https://phescreening.blog.gov.uk/2021/07/01/nipt-rolls-out-to-all-areas-of-england-as-part-of-the-existing-nhs-screening-pathway-for-downs-syndrome-edwards-syndrome-and-pataus-syndrome/
- Global Non-Invasive prenatal testing (NIPT) industry (2023) ReportLinker. Available at: https://www.reportlinker.com/p06032345/Global-Non-Invasive-Prenatal-Testing-NIPT-Industry.html?utm_source=GNW
- Wise, J. (2022) ‘Non-invasive prenatal screening tests may give false results, warns US Regulator’, BMJ [Preprint]. doi:10.1136/bmj.o1031.
- Gil MM, Quezada MS, Revello R, Akolekar R, Nicolaides KH. Analysis of cell-free DNA in maternal blood in screening for fetal aneuploidies: updated meta-analysis. Ultrasound Obstet Gynecol. 2015 Mar;45(3):249-66. doi: 10.1002/uog.14791.