<prompt> Karyotyping of the fetus can be done routinely through all of the following invasive method except:Chorionic villus samplingCordocentesisAmniocentesisFetal skin biopsy  <response>: There are three routine ways of obtaining fetal tissue for karyotyping: Chorionic villus sampling - done at First trimester10-13th weeks Amniocentesis - done at second trimester16-18th weeks Percutaneous umbilical blood sampling cordocentesis - done after 18 weeks. 