Measurement via the belly

Hi! I have a question about measuring the cervix. I had my 20-week scan today and everything with the baby was fine. However, they saw via the abdominal scan (so not via internal scan) that my cervix is short (17mm to be exact). This scan was done at a different hospital than usual due to circumstances. Tomorrow I have an appointment again at my own hospital with my own gynecologist. They will then check internally. Does anyone happen to know if you can see it just as well via the abdominal scan as internally? Is it still possible that the cervix is actually fine when they check internally, or should I assume it's really short?

Love!