A women undergoes a chorionic villous sampling at 11 weeks gestation. The result shows two cell lines - 46 xy and 47 xy + 21 what is your next step

This is a case of mosaicism. In most cases, the mosaicism reflects confined placental mosaicism rather than true second cell line within fetus. Amniocentesis should be offered, and if results are normal, mosaicism is presumed to be confined to placenta. Confined placental mosaicism can cause IUGR and stillbirth.