Us vs blood test

We had our anatomy scan today and also got the blood results from an at home blood test we did for gender from sneak peak as well. We handed over results to our friend so she could order our cannons for the gender reveal, problem is each result said something different. I told her go with the us as you can contaminate the blood test and maybe I did? I was really careful with the blood test tho. I’ve no idea which test said what. Wondering which test everyone would have believed.