Fetal Karyotyping (amniocentesis or chorion villous sampling )
When is this exam indicated?
Fetal karyotyping is indicated in case of high-risk for genetic or chromosomal abnormalities, such as in case of fetal malformations or soft markers. Amniocentesis is carried out at 16 weeks or more and CVS at 11 weeks or more.
How is it performed?
After skin disinfection a simple needle enters maternal abdomen acquiring amniotic fluid or placental trissue under continuous ultrasound guidance. The procedure duration is about 1 minute and local anestetic to the abdominal wall can be used, if required. After the procedure fetal wellbeing is checked by ultrasound.
Maternal infections controindicate chorion villous sampling; thretened miscarriage or vaginal bleeding generally controindicate both invasive procedures.