hi, thought i'd share my thoughts about oscar. my gynae suggested oscar, but didn't say i must go, probably because i am <35 and no down syndrome case in my family. gynae say it is not a diagnostic test, more like a probability test , so also not a pass-fail test for sure. oscar consists of a NT scan, which measures the baby nuchal fold thickness and a blood test based on your blood.
hubby and i decided not to go for it in the end. because i am not comfortable with it being only a probability test, which will bring some amount of anxiousness. and if it is bad results, to go for amnio, i feel is highly risky for twins, especially as mine are identical twins sharing one chorion. only invasive testing like amnio can tell 100% whether got DS or other problems or not. we choose to shui2 yuan2, what will be will be.
of course there are people who would want to know and be prepared should there be any problems with the babies. *touchwood* it's a choice for parents-to-be to make, unless the gynae insists for medical reasons. my gynae also say that such tests can help him know what to watch out for that may be highlighted in the results.
serene, looks like your test is not Oscar, but a NT (nuchal translucency) scan and a FA (fetal anomaly) scan. by the way, in the first trimester, the babies get their nutrients from the yolk sac (or whatever it is called), so don't worry too much about them if you are not eating well in first tri. try to catch up in 2nd tri. good luck!
spiffy, i believe oscar results from the blood test will be adjusted for twin pregnancy if the lab is aware of it. it would be a waste of $$ if the test results are not usable!