If i passed a sac with white tissue 5 wks ago will an ultrasound still be able to show that i had a miscarriage?

Unlikely: If you completed a spontaneous miscarriage, also known as spontaneous abortion, and not residual tissue remains, then it is very unlikely an ultrasound will detect any abnormality. I hope you are feeling well after this ordeal.

Maybe: the sac may not have been the pregnancy. get an ultrasound and sequential blood pregnancy tests if needed to determine the situation