The antenatal screen is a selection of blood tests and a urine test. The urine test looks for evidence of infection and also for the presence of protein in the urine. The blood test looks for the Blood Group and any unusual Antibodies, Full Blood Count (which checks for anaemia), Rubella immunity (German Measles), exposure to Hepatitis B and Syphilis. In certain situations we may also check for Hepatitis C, HIV infection, Vitamin D and thyroid function.
Nuchal Translucency Ultrasound
The Nuchal Translucency ultrasound is usually done between 11 and 14 weeks gestation. It looks for chromosomal abnormalities such as Down’s Syndrome (Trisomy 21), Edwards Syndrome (Trisomy 18), Patau Syndrome (Trisomy 13) and also sex chromosome abnormalities. This test detects about 90% of baby’s with Down’s Syndrome as high risk. Although this test is recommended for mothers 35 and older, who are at a higher risk of having a baby with Down’s Syndrome, the test can be done by any mother who is concerned about having a baby with Down’s Syndrome.
Non-Invasive prenatal testing (NIPT)
The NIPT test is done after 10 weeks gestation looking for chromosome abnormalities of Trisomy 21 (Down’s Syndrome), Trisomy 18 (Edwards Syndrome), Trisomy 13 (Patau’s Syndrome) and sex chromosomal abnormalities. The test can detect 99% of baby’s with Down’s Syndrome and is more accurate for detection of Down’s Syndrome in comparison to the Nuchal Translucency test. The test involves taking a maternal blood sample and looking for cell-free DNA circulating in the mother’s blood. The NIPT test can also be combined with an ultrasound done at 12 weeks gestation
Amniocentesis or CVS
These are invasive procedures looking for chromosomal abnormalities or genetic abnormalities of a baby. These tests can also be performed when a NIPT test or a Nuchal Translucency test shows a higher risk of having a baby with a chromosomal abnormality.