Current screening practice in the UK All pregnant women booking before 20 weeks in England, Scotland and Wales are offered antenatal screening tests for fetal anomalies. The Eetal Anomaly Screening Programme (FASP) offers women the option of the combined screening test between 11+2 and 14+1 weeks or the quadruple screening test for women presenting after this time up until 20 weeks, to screen for Down's syndrome. When the results of these tests indicate that a woman has an increased chance of having a baby with Down's syndrome, invasive testing is offered to confirm the diagnosis. Invasive testing by chorionic villus sampling (CVS) or amniocentesis both carry a risk of miscarriage (around 1%) and therefore women can use the results of their screening test to decide whether it is appropriate for them to risk miscarriage in order to confirm a diagnosis. In the future, these tests may be replaced in part or wholly by non-invasive prenatal testing (NIPT), which uses cell-free fetal DNA found in the mother's blood. Although NIPT for aneuploidy is not currently offered by the NHS, it is widely available privately from 10 weeks gestation and currently two large evaluation studies are underway in NHS hospitals. Later in pregnancy, between 18+0 and 20+6 weeks, a more detailed ultrasound examination for structural fetal anomalies is offered. This detects many abnormalities of the nervous, cardiovascular, respiratory, musculoskeletal, and renal systems.