An ultrasound is a type of diagnostic equipment. Meaning it can be used to see and diagnose problems. I have a better idea though: Get a different doctor. 20 weeks is a long time to wait. I am 7 weeks and my doctor did my first one already. I am getting another one next week because they couldn’t see anything except a sac. Most doctors will at least do an ultrasound at 12 weeks. Just so you know they will be doing it transvaiginally. So it won’t be like you see on TV. They will put a wand up your cavity and examine the uterus from there. If you have insurance and you get a different doctor then you should not have to pay for any ultrasounds. Here you will get more information about diagnostic ultrasound doctors.