Genetic testing

My doctor pushed today for me to go for the quad genetic testing. I had the first trimester genetic testing and that cake back normal. I had 20 week ultrasound done today and the ultrasound tech said everything looks perfect I should t worry. My doctor will be sending the results out to high risk fetal survey but she does that with all ultrasound pics.

I guess my question is why would I need genetic testing if my ultrasound is fine? I never even was offered it with my first.