Just had pelvic mri w contrast. no fluid in tubes or uterus (us showed yesterday!) how could this be? which to trust?

Possible: Us is not as accurate as mri. But body is a dynamic environ ment, which changes constantly. Particularly the gestational tissues are very dynamic....Things can change over night.

Seek doctors guidenc: Your primary care doctor needs to help explain this discrepency which can be best sorted out by the radiologist. I do know that ultrasound is not a 100% reliable test. It is good for screening only. Confirmation is more reliably done with a MRI or ct scan. Since your MRI is fine, i would trust the mri. If you have any symptoms, next time get a ct scan done.