Fetal Abnormality Screening

These are non-invasive tests designed to assess the risk of certain genetic disorders or birth defects in each individual pregnancy. These tests may help couples decide if they want to proceed with confirmatory invasive tests such as Amniocentesis.

 

Nuchal Translucency
Nuchal translucency (NT) assessment performed between 11-14 weeks of pregnancy measures the thickness of a fluid-filled area behind the fetal neck, following strict adherence to standard NT measurement techniques. Down Syndrome babies are usually associated with a thicker than average NT.

 

Nasal bone
Nasal bone ultrasound scans which reveal an absence of a fetal nasal bone, along with a thickened NT, is associated with a higher risk of having a Down Syndrome baby.

 

Serum screening
Maternal serum screening performed between 11-14 weeks or 15-20 weeks may be used alone or in combination with NT and nasal bone assessments to increase the detection rate of Down Syndrome while minimizing the need for invasive testing.Chromosomes carry genes that pass certain characteristics from parents to their children. When there are too many or too few chromosomes, or there is a defect in a chromosome, birth defects usually occur.Amniocentesis is a invasive antenatal test that is performed to detect fetal abnormalities, in particular due to chromosomal problems, such as Down’s syndrome. Amniocentesis is usually done if there is a high risk of fetal abnormalities following serum screening tests or ultrasound scans. These tests are also usually offered to women who have an increased chance of having a baby with a disorder eg women over 35 years old, women who have had a previous Down Syndrome child or other chromosomal disorders, or women who know that they or their baby’s father have an unusual chromosomal arrangement. It is not usually offered on a routine basis.During amniocentesis, a needle in inserted through the women’s abdomen into the amniotic sac under ultrasound guidance and a sample of amniotic fluid is taken and sent to the laboratory for analysis.