Moms of 1+ C-sections- advice needed!

DawnJM25

I'm about 10 weeks along and just had my first ultrasound today.  I saw a healthy fetus with a beating heart (yay!) BUT, the radiologist also saw a sac with some scar tissue that he assumes is left from my previous C-section.  He referred me to an OB specialist for another ultrasound.  I know radiologists aren't OBs, and when I asked he couldn't even tell me a worst case scenario.  He said sometimes this is nothing, but it could be cause for concern.  DD is only 9 1/2 mo.  DH and I hadn't planned on getting pregnant so soon- it was a big surprise! 

Anyway- I'm concerned about this sac of scar tissue and what it might mean?  Has anyone else had this experience?  What is the worst case here?