Noninvasive prenatal blood test

Alrighty, so I've read a few places that they give this test and it takes your blood, out of your arm, and tests for abnormalities and the gender. Is this correct? Because some say that it can cause miscarriage and that doesn't make sense unless the needle is going into your stomach. Taking your blood won't cause a miscarriage.. so is it the test that goes into your arm or your stomach. I want one that takes my blood from my arm and tests that stuff. Is that possible? Is that what it is?