This technique can allow testing of fetal genetic material and the commonest indication is for diagnosis of chromosomal abnormality eg Down’s Syndrome. It can be performed after 16 weeks of gestation. Before the procedure, the doctor would perform ultrasound scan to map a suitable position for sampling. Afterward, local anesthetic would be infiltrated to part of the maternal abdomen. During the procedure, a needle would be inserted into the placenta through maternal abdomen and uterus to obtain amniotic fluid. The whole procedure will be under ultrasound guidance. It is an invasive test which would increase the risk of miscarriage by 1%.

入侵性染色體異常遺傳性疾病檢驗