My nuchal u/s came back high risk 1:52 my baby has downs. just wondering what exactly my percentage is and what happens next?

Probability: 1:52 is a high risk number, so your chances of this pregnancy actually resulting in a baby with Down syndrome is 1 out of 52 pregnancies, or about 2% chance. While that number seems low, the age-adjusted risk for young mothers (20-25yrs old) in the USA is more like 8 per thousand, or 0.8 % - the test is telling you your pregnancy carries a risk almost 3 times the normal risk for your age group

Next steps depend on: whether you had combined 1st trimester screening test or integrated screening. For the latter, you'd have blood drawn in both the 1st & 2nd trimesters. You may have a Fetal Ultrasound for other anatomical markers of DS & a test of fetal DNA circulating in your blood. If your calculated risk remains high, you'll be offered a diagnostic test for Fetal Chromosome Analysis & genetic counseling.