Hi, I just had my first ultrasound last week to determine the due date. I was told to drink a litre of water before coming to the ultrasound so I had a full bladder. The dr tried doing an external but could only see the gestational sac so told me to go empty my bladder (thank god - pressing on the tum is not good when you've got a full bladder) and then he did an internal ultrasound - it was awesome (not the dildo cam lol), I got to see my little one's heart beat and everything. He/She was 5 weeks, 3 days and this is my first child.