Is it possible to measure close to 3 weeks behind on transvaginal ultrasound? u/s showed fetal pole measuring 6 weeks w/ no heartbeat yet.

Transvaginal USG: Transvaginal ultrasound is most accurate duringvthe first trimester by 5-7 days. If >than 1 week off then your dating may be off because of ovulation etc. your period also plays a role in this. If your cycles are irregular then ultrasound dates may be off. Would considerva repest ultasound in a week to evaluate and see if pregnancy is progressing. Good luck.