Your first question and answer is against medical ethics. If you’re a physician you know that terminating pregnancies based on a non-specific but sensitive screening test is inappropriate (do no harm).
However, you are correct in your second statement - there are much more specific follow up tests which improve diagnostic accuracy.
Medical utilitarianism should never be so cruel and gruesome as to eliminate 85 healthy and wanted pregnancies in order to find and eliminate 15 genetic aberrations.
