Nuchal Translucency Screening
This is a non invasive screening test that is performed between 12-14 weeks of pregnancy to assess the risk of having a baby with a chromosome abnormality.
This screening test allows up to 95% of babies with Down syndrome and other abnormalities to be identified. This test uses a combination of ultrasound and a blood test.
How is this test performed?
A transabdominal ultrasound examination will be performed and this will check the physical appearance of the baby, most importantly, it will measure the thickness of the skin at the back of the baby’s neck. The presence of the nasal bone will also be assessed. In some patients it may be necessary for a transvaginal examination to be undertaken for an accurate measurement.
How is the risk of abnormality tested?
Studies have shown that up to 95% of babies with Down syndrome or other abnormalities can be identified using this screening test. A program will calculate this risk, taking into account the results of the blood test, NT measurement (from ultrasound), the mother’s age, the dating of the pregnancy and any previous history of pregnancies with a chromosomal abnormality.
A High Risk Result – what does this mean?
A “high risk” result does not always mean that a baby is abnormal. A risk greater than 1 in 300 is considered as being “high risk” and for these patients further testing such as CVS (Chorionic Villus Sampling) or Amniocentesis would usually be recommended. There is also the option of a further blood test, the Non-Invasive Prenatal Test ( NIPT), which can also be used to assess the risk of chromosome abnormality in the baby.
A “high risk” result, in a baby with normal chromosomes, can indicate an increased risk of a fetal heart abnormality and/or concerns with the growth of the baby during the pregnancy. If there are concerns about any abnormality at your ultrasound these will be discussed with you and careful assessment and monitoring of the baby is usually recommended at 16 and 20 weeks of pregnancy.
A “Low Risk” Result –what does this mean?
A risk lower than 1 in 300 suggests a low chance of chromosome abnormality for your baby, but, this DOES NOT mean no risk.
Should you have any questions regarding the above information or your ultrasound examination please do not hesitate to ask the Sonographer or Dr Susan Winspear.