Karyotype Analysis of Amniotic Fluid
10mL amniotic fluid was obtained and cultured at 37℃ with amniotic fluid
culture medium (Guangzhou Baiyunshan Baidi Biotechnolgy). Before
harvesting, 120 μL colchicine (working concentration 50 μg/mL) was added
and incubated for 25 min at 37℃. After that, 2 mL pancreatin (Gibco) was
added to stop digestion. Unlike peripheral blood, 6 mL of 1% sodium
citrate solution was used for hypotonic treatment before 1 mL fixed
solution (methanol : glacial acetic acid = 3 : 1) was added for
fixation. Total 50 GTG-banded metaphase chromosomes were analyzed. For
samples with abnormal chromosomes, a total of 100 metaphases were
analyzed.