BIRADS 0 for focal asymmetry

I had a screening mammogram and ultrasound last week. My ultrasound came back all clear, but the mammogram noted inconclusive results due to focal asymmetry in my left breast. I go back in two weeks for a diagnostic mammo and ultrasound.

I’m wondering if anyone has experienced this before and what the outcome was, especially with a negative ultrasound. No calcifications or masses were noted on either report, but I do have dense breast tissue. Wondering what the chances are that the mammo is hiding something not seen on the ultrasound.