The stem states that the mother is 12 weeks gestation. CVS is performed 1st trimester, usually b/t 10-14 weeks gestation according to Up-to-Date. Amnio is performed after 15 weeks. From Up-to-Date: “Amniocentesis should be performed after 15 weeks of gestation because earlier procedures are less likely to be successful, are associated with higher rates of cell culture failure, and carry greater fetal risks.”

Amniotic fluid phospholipid analysis is used for testing fetal lung maturity via measuring surfactant production.

Fetal echocardiography would reveal any congenital heart defects if present, but would not be diagnostic of Downs syndrome

Fetal ultrasound First-trimester ultrasound commonly shows increased nuchal translucency and hypoplastic nasal bone. But I feel this is used more commonly in older women who might have chromosomal dysgenesis as the cause of downs syndrome

Fetal biopsy Pretty invasive technique, when we have a lesser invasive and more specific test available.