cervix length

xtina6143

I have been concerned about an incompetent cervix and I called my doctors office and spoke with a nurse to get my cervical measurement from my 19 week ultrasound and she told me my cervix measured equal to or greater than 3 sonometers. does anyone have any idea what this means? She didn't know and said I would have to wait and ask my doctor when I go back the 28th but I'm anxious and dont really want to wait that long