In addition to evaluating for birth defects, benign changes also known as soft markers are examined.Some fetuses with Down syndrome, trisomy 18, trisomy 13, or other chromosome problems will have birth defects or other physical changes that can be seen on ultrasound.The test cannot diagnose or definitively rule out these conditions, but instead determines if the pregnancy is at a normal or increased risk.If the test result shows an increased risk, the patient will be offered additional testing to better assess the risk/and or provide a definitive diagnosis.
This NT measurement is often increased in fetuses with these chromosome conditions and the nasal bone may be formed differently.
Ultrasound in general is used to provide accurate dating of a pregnancy and to evaluate the fetus's physical growth and development.
An ultrasound at 18-20 weeks of pregnancy, a detailed or level II ultrasound will measure and evaluate the bones and internal organs for signs of abnormalities.
Because all pregnancies have some level of risk/chance to be affected by chromosome abnormalities, this test is recommended for all pregnancy women.
In particular, women that are generally thought to be at low risk ( Maternal serum screening (i.e.