karyotyping
Last reviewed 01/2018
This is the most common indication for amniocentesis, often in women concerned about Downs syndrome.
In amniocentesis the cells are derived from the foetus and the amnion. They grow slowly and so a result may take between 2 and 4 weeks to arrive.
In CVS the chorionic tissue grows rapidly and a preliminary chromosome count may be available in 24-48 hours. A full report will take 2 weeks.