Yes you definately see more with an internal u/s. They usually do both however and combined the two. I think abdo they see from a different angle from vaginal thus why they put the two together.
As for having AF I guess it depends on if its a heavy flow or just a tiny bit. I'd call to ask if its a problem having AF. I had one when I was bleeding to see if the pregnancy was viable so they do do it when your bleeding but for a normal u/s to check everything for fertility say then maybe they would prefer you not bleeding. Just call and ask.
I'd agree that it's worth calling to ask. FWIW, I know its very common for women undergoing fertility treatments to get internal u/s done on CD2 or 3, so it may not be a big deal for them?
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