Genetic Sonogram or the risk reassessment scan is generally performed
when the Down syndrome risk has increased on an earlier biochemical
In this an ultrasound is performed looking for specific ultrasound
features or soft markers suggestive of T21 such as nuchal fold, nasal
bone, mild ventriculomegaly, aberrant right subclavian artery.
Specific features are checked which either increase or decrease the risk
of Down syndrome.
At the end of the scan a new probability risk for Down syndrome is
given. The genetic sonogram is only 56% efficient at detecting Down
syndrome at a false positive ration of 3%.
The genetic sonogram, also called a targeted sonogram or Level II
sonogram, is performed at 15 to 22 weeks into the pregnancy. This
ultrasound scan includes an examination of the developing fetus, the
uterus, placenta, cervix and the regions of the ovaries.
At 15 to 22 weeks, we perform a detailed evaluation for abnormalities of
the baby, including a comprehensive look at the structures of the
developing brain, the face, lips, nose and profile, and also the spine,
heart, abdomen, kidneys, bladder, extremities and umbilical cord.