Try calling before you go because they were running extremely late when they did mine. I had to become pretty hysterical before they rushed me in (none too soon). I had both types of ultrasounds while I was there. Neither hurt (however the external one pushed on my FULL bladder something fierce - that was a little painful).

From what I understand an ultrasound is a normal thing for them to require especially if things are not "right" there. Good luck!