Genetic testing

Tianna

So yesterday I got my NT scan and they did blood work. From different pregnancy forums, I read that the blood work is usually a finger prick. But when I got mine they took a full vial of blood and the ultrasound tech had explained beforehand that they’d test the chromosomes and things like that. But when I asked could they determine gender they said no. But wouldn’t they be able to tell since they’re checking the chromosomes?