Amniocentesis
Amniocentesis can accurately diagnose Down’s syndrome and other foetuses with chromosomal and genetic diseases.
Amniocentesis is performed at 16-20 weeks.
PCR test for Down’s syndrome will be available 2 days later.
Karyotype test results will be available 15 days later.
Array CGH test results will be available 15 days later.
The procedure involves introducing a needle through the abdominal wall guided by ultrasound imaging. 20ml of amniotic fluid is taken for chromosomal analysis and the foetus is not harmed during the procedure. The amniotic fluid consists mainly of foetal urine and will replenish itself within a few hours. The procedure requires no anaesthesia. The risk of miscarriage as a result of this procedure is about 0.5%. The major drawback of amniocentesis is that the result is only available beyond 16 weeks of pregnancy, which means that if the foetus were to be aborted because of serious abnormality, it would be a late termination of pregnancy.