I had a vaginal ultrasound Wednesday for a cyst in my ovary. I am a week late for my period and have pregnancy symptoms, would they have been able to tell if I wad pregnant during the ultrasound?

Possibly, but it may have been too early yet. Usually a gestational sac can be seen at about 4 weeks. Was this at your gyn's office? Did you mention that you were late for your period? If so, they likely would have checked with a urine test.

If not, since you are late, try a pregnancy test.