Since the first application of ultrasound to it 50 years ago, the “black box” that is the pregnant uterus has gradually yielded to efforts to gain increasingly precise information about the condition of the fetus. Technological advances in ultrasound and, more recently, magnetic resonance imaging have seen the production of high-resolution displays of fetal anatomy and physiology. Specific information about the fetal genome, however, has until now only been available through the application of invasive techniques. Amniocentesis and chorionic villus sampling have been used to diagnose fetal aneuploidy (such as Down syndrome) and an ever-increasing range of genetic conditions. But these invasive procedures come at a cost — an associated 1% risk of pregnancy loss1 limits their application and causes significant stress for women thinking of undertaking such testing. Screening tests such as ultrasound and maternal serum screening to assess aneuploidy risk have been developed to allow more judicious application of invasive procedures, but of themselves cannot accurately diagnose the fetal condition, and false negatives and positives both occur.

©The Medical Journal of Australia 2009 www.mja.com.au PRINT ISSN: 0025-729X ONLINE ISSN: 1326-5377