NIPS and Serum Screening

Down Syndrome occurs if a baby has three copies of its 21st chromosome instead of two copies. A chromosome is a bundle of genetic material, and if you have too many or too few of these bundles, severe abnormalities can result. In the case of Down Syndrome, these abnormalities include intellectual, heart, thyroid and other endocrine, facial appearance and others. It is possible to detect early in the pregnancy whether your baby might be at high risk of having Down Syndrome. This is possible through consideration of your age and additional tests. The additional tests are Combined First Trimester Screening and Non-invasive Prenatal Testing (NIPT). It is important to realise that both of these tests are considered to be “screening test”. This means they won’t tell you “yes, your baby has Down syndrome” or “no, it definitely does not have Down syndrome”. They will, however, say if your baby is at high risk of having Down syndrome, in which case you should have a diagnostic test. A diagnostic test is one that will tell you “yes” or “no”. Combined First Trimester Screening requires a blood test at 10 weeks and an ultrasound between 12 and 13 weeks. Most patients choose this option. The blood test costs about $120 (no medicare rebate) and a specialised ultrasound costs about $150 after the medicare rebate, however this varies from clinic to clinic. Combined First Trimester Screening screens for Down syndrome and Trisomy 18. The detection rate for Down syndrome is 90%. NIPT is no doubt the future of prenatal testing for Down Syndrome and other genetic abnormalities due to its incredible accuracy and lack of risk to the baby. It uses a maternal blood sample to find and test the baby’s cfDNA(cell free DNA - genetic material) in the mother’s bloodstream. Costs are constantly falling, but it is quite expensive costing about $550 and no rebate applies. This non-invasive prenatal test (NIPT) is safe and poses no risk to mother or baby. It’s recommended that expectant parents discuss with their health practitioner the limitations and advantages of cfDNA screening before having the test. Most women would still opt for a 12 week ultrasound if doing NIPT; whilst the ultrasound has no impact on the Down Syndrome result when doing NIPT, it does provide other useful information about the development of the baby; so a saving is often not made by omitting the ultrasound. Lenore will discuss these options with you in detail at your first pregnancy appointment. You can find out more information here