Question about NT scan/integrated test results

OSUx2

After the NT scan and bloodwork my dr does not give the odds, she wait's until the second round of bloodwork to look at the entire picture because it is more accurate and then gives the odds.  I've only seen the odds for after the first round and at my last appointment she said that my odds are less than 1 in 5000 for both downs and neural tube defects (and I have a elevated risk with my age and a family member with downs).  I know those are super low I'm just confused because I have never seen numbers that "low".  I've seen 1 in 1500 or so but never over 2000.  Is there an actual chart for the full test results not just after the first part?  Maybe I'm being paranoid that my dr accidentally added an extra zero and my odds are 1 in 500 but I can't seem to find more detailed info.