OSCAR stands for 'one stop clinical assessment of risk', and is a method for giving a Down's risk based on one visit to a clinic between 11 weeks and 13 weeks 6 days. At this visit a nuchal scan is performed, which is combined with a two hormone blood test (papp-A and hCG) at the same time. A combined Down's risk assessment can then be given. It's a convenient and quick test-the disadvantage is that the two hormone blood test is probably not as accurate as a multi-stage integrated test or variant of this including the triple test.