<prompt> Which of the following is the investigation of choice in a pregnant lady at 18 weeks of pregnancy with past history of delivering a baby with Downs syndrome.Triple screen testAmniocentesisChorionic villous biopsyUltrasonography  <response>: Answer is B Amniocentesis: The ideal investigation in a mother with a pregnancy at risk previous child with Downs at 18 weeks gestation is amniocentesis. 