How accurate is the blood gender test?

We had our 12 week appt today. My dr highly recommended the genetic testing. He said everything looks great but he likes to see his patients have that done. Part of the testing is also telling the gender. I asked for that part to be listed separately and sealed which they can do. DH and I are not sure when we went to know yet, but also aren’t sure how accurate they are. We don’t want to do a gender reveal if there’s a high chance of it being wrong. My SIL did have it done at 10 weeks and it was accurate but she’s the only other one I’ve known that had it (didn’t know that was even an option before she did it).

Have many others on here done the blood test vs ultrasound and was it accurate? Is it more accurate than the ultrasound?