I had a vaginal at 4,5,6 weeks and then when I went in for my 8 week 4 day appointent they found that baby externally and it was moving all around:) I have heard 10 weeks though, I guess it depends on the equipment also but I say around 8-10 weeks.
I had abdominal u/s yesterday at 8 weeks 5 days, found baby straight away.
I am having mine done on December 15 for a second time on the belly. The first on was both internal and belly at 8 weeks
I just had an u/s done on Monday at exactly 8 weeks. My midwife advised me to have a REALLY full bladder so that an external would be more effective. It worked...never needed internal.
I had an abdominal ultrasound and i was 7wks 2 days. YOu have to make sure you drink enough water. I had drank enough water and the utlrsasound tech said perfect and we were able to see everything clearly.
From what i hear the internal tends to be for the first ultrasound and then they move on the the belly one.. my first ultasound was this week at 11 weeks 1day and so it was internal (I did not know this until i got there lol)
I decided to ask them the day I went for my 11 week ultrasound because I wanted to be prepared. Luckily they said they shoot for the belly one but if they can't see they move to the internal. But for me they luckily were able to see it with the belly one!
I just had my 10th week US and it was internal.... It will probably be that way for 2 more weeks until I move to a regular dr. I'm at a fertility clinic right now.