I think drinking a lot of water before an ultrasound improves the chance of getting a good ultrasound. And some people don't drink enough so they tell everyone to drink a lot. I go to a fairly new practice and they told me to drink at least 16oz an hour before coming in.
I was told it makes for clearer ultrasound and makes it easier to measure your cervix
No, it's not that they don't know what they're doing. Depending on the type of machine/equipment they have it is more helpful for you to drink water beforehand. Sometimes even with the newer machines that can see well, people still practice things the old way and are used to telling patients certain things. Also, depending too in your body type, it will help them see certain structures better. And by that I don't mean the baby. I mean u. I'm petite but even for me I had to really pee beforehand n didn't think anything of it so I went and when I was called the technician said she would have been able to see my cervix better had my bladder need full. So she used the vaginal ultrasound which they charged me an extra $100 for
My ultrasound tech said they needed to look at my bladder as well as the baby so my bladder had to be full
Having a full bladder helps elevate your uterus, so it isn't hidden in your bladder or bowels. This makes the picture much clearer.
It also depends on how far along you are. Early on in pregnancy a full bladder is necessary or they will do the internal. They still might do an internal if certain structures can not be seen. Further along in pregnancy having a full bladder is not necessary