Bubblymommy, over here, beside the blood test, have to do the NT scan. Together, they are know as oscar test in Singapore.
When the results contradicted in NT Scan and blood test, other tests are suggested like CVS and Aminiocentsis(no sure about spelling) to confirm whether bb has down. The blood test is not very reliable for my case, it shows bb has a high risk of down's syndrome, so genetic counsellor suggested the other two tests for us to choose one. I went for CVS.