Just like chorionic villus sampling (CVS), a procedure done in the first trimester, amniocentesis produces a karyotype — a picture of your baby's chromosomes — so that your caregiver can see for sure if there are problems.
The tenth week is usually the time that a chorionicvillus sampling (CVS) is performed, which will check for genetic abnormalities like sickle cell anemia, Down Syndrome, cystic fibrosis and Tay - Sachs disease.