passages.id: split_6_test_76_passage
passages.type: progene_text
passages.text: 548 cell cultures and karyotypes obtained by early amniocentesis with filtration technique ( EAF ) at a mean gestational age of 12 1 / 2 weeks were compared with 555 obtained by transabdominal chorionic villus sampling ( CVS ) at a mean gestational age of 11 weeks .