Cervical length Ultrasound?

Several weeks ago i sae my midwife for my initial apt to meet my midwife and get medical care established for this pregnancy. She asked if i wanted to see the baby and of course, i said yes. At the time i was only 7 weeks but we couldnt see anything through the regular ultrasound (except for several cysts that she mentioned but didn't say she was concerned about) so she went ahead and did vaginal. She said baby looked great but wanted me to come back for another u.s. to get a better idea of a due date. So last week I went in for a routine ultrasound (I did not see my midwife at this apt) and the tech said she didn't see anything that would normally concern her and gave me a due date of June 20.

Today I got a phone call from my office saying my midwife looked over my ultrasound and wants me back in as soon as possible for a cervical length scan. Has this happened to anyone else? What were your results? What does this normally mean?

Anything to calm my wondering mind would be helpful :/