What does it mean to have Large veins by cervix additional ultrasound needed please help!

I received results from my 3rd trimester ultrasound and my doctor told me baby Parker is growing great but she was concerned and that they found large viens by my bladder near my cervix and that I needed to get a high risk ultrasound at a specialist center. I think I was overwhelmed and didn't know what to ask so I said nothing, now I am freaking out what would this even mean I'm just confused!