Has anyone had an abortion in the second trimester for medical reasons?

Im 16 weeks pregnant and my husband and I just found out our baby has anencephaly, which if you're not sure what that is its a neural tube defect that no babies survive because there is no brain or skull, so my baby will either p on sometime during my pregnancy or a few minutes after birth so my doctor highly recommends me to have an abortion because me carrying him can cause my amniotic fluid to dangerously build up since the baby cant swallow it, and Im a short Petite person. This is the hardest thing Ive ever had to do and I was just wondering if anyone could tell me what to expect when they do the procedure cause Ive never had this done before, I don't need to know your reasons for doing it just any advice on what to expect, I have no idea how they do this procedure so far into the pregnancy. Thanks