We've just returned from an early scan where we saw our baby wriggling with a strong heartbeat. The measurements were exact to the 8 weeks and 5 days we had expected to be. However the sonographer mentioned that she was unable to see the yolk sac and so it might have been dissolved already and using the placenta. Is this normal? I didn't think this happened until 12 weeks. I should have asked when I was there but she didn't seem concerned and I was a little overwhelmed! Does anyone have a similar experience or knowledge of whether this is normal?