Infected in cmv prior to pregnancy. i realized there was no risk to the fetus. i want to perform amniocentesis. is amniotic fluid used to do 16 20 wee?

Possible...: My advice would be to pose this question to your ob/gyn. As you will not be the one performing the actual procedure; best to ask the professionals. There is always a small risk of miscarriage after an amniocentesis; albeit minute...So best to discuss this with your obstetrician.

Ultrasound: If the baby is growing and otherwise you are well, it may not be necessary. If there is some indication that the baby is affected, then the fluid analysis may be useful and usually can be performed safely.