Prenatal screening tests: are they accurate?

Prenatal screening, unlike genetic testing, is done without any previous indication of a genetic disorder. Dr Melita Irving is a leading London-based clinical geneticist with extensive experience in diagnosing and managing a wide range of genetic conditions. In this article, she provides you with insight into prenatal screening.

What are prenatal genetic screening tests?

Genetic testing is available if your baby has a risk of inheriting a condition running in your family or has physical anomalies on ultrasound scan.

Genetic screening, on the other hand, is done ‘blind’ and is designed to give reassurance to worried would-be parents with no prior concerns. This is usually in the form of chromosome analysis. DNA extracted from a CVS (chorionic villous sample) or amniocentesis is needed and later on, it is found in the mother’s blood (non-invasive prenatal testing – NIPT).

How accurate are prenatal screening tests?

Prenatal testing for a specific genetic change is extremely accurate, but prenatal screening may be less so and cannot be completely reassuring – the tests are only as good as the question they are being asked.

What should I consider when deciding whether to have prenatal genetic testing?

It should be based on your individual situation and because it can be difficult to know whether you need genetic testing or not, a clinical geneticist can help you work out if testing would be helpful.

Can I do anything before I get pregnant?

Carrier testing for you and your partner is available. This test determines yours and your partner’s risk of being a carrier for specific genetic disorders.

Where could I learn more?

Melita Irving is the author of Haynes Human DNA Manual – Understanding your genetic code

Haynes Publishing 28 Oct 2019

ISBN-10: 1785215949

Melita Irving is a consultant in clinical genetics and available to help you and your partner with a screening test and if needed, the management of genetic conditions. Click here to learn more and to get in touch.