Amniocentesis is a technique for the diagnosis of congenital abnormalities before birth. By karyotypic studies of somatic cells, abnormalities due to changes in chromosome number like Down's syndrome, Turner's syndrome, Klinefelter's syndrome, etc, can be determined.
It can be used as a pre-natal diagnostic technique. These days, amniocentesis is being misused also. Mothers even get their normal foetus aborted if it is a female.