That is way early. My doctor won't even see me until 8 weeks let alone doing a U/S. Don't worry,
I was five weeks and didn't see anything on mine.
Four weeks is still really early to see anything. as long as your hcg levels are rising, and you aren't bleeding, then things are progressing.
Dnt worry; I did and was stressed; I am 5 weeks and went in at 4 weeks and they saw nothing! No sac; nothing I did my hcg blood on tht day; a Friday it was 1832 and did it today and it is 8740; the doc is happy with results and I will do an ultrasound @ 8 weeks; keep me updated; or try n friend request; we should b due. Around same time
Actually it is still so small, it'll be too hard to see. Most of the time you can't see the sac through transvaginal ultrasound until 8 weeks. Don't worry just yet :)