Fiona - I had an early ultrasound at 6w5d because i was paranoid of another m/c(already had 2) So i explained this to my GP and she gave me a referal. Some people also need one to check for EDD as they have long cycles or irregular cycles etc. All i saw at 6w5d was a small blob and something pulsating which was its heart but you couldn't see the baby moving at all and that was with the internal ultrasound all she could see with the external one was the sac. So if you were tog et an early scan i'd say about 7-8 weeks would be better.