Fetal echo

Has anyone had a fetal echo done? My OB said she wants me to have one because of my diabetes. At my 20 week scan the tech just kind of skimmed over my baby’s heart since she knew about the fetal echo but said that to her it doesn’t look like I have too much to worry about. But of course I’m still a little freaked out. I know it’s just something my OB wants to do for piece of mind but it’s all I can think about haha. Was wondering who else has had one and what I should expect? They told me it could take up to two hours.