I'm 7 weeks pregnant. i had a transvaginal ultrasound today and was told there's only a few days growth since last week, and no heartbeat. dr said there's a slight chance i could be earlier than thought. how accurate are measurements when that early?

Very accurate: A transvaginal untrasound can detect a fetal heartbeat with very high accuracy as early as 6- 7 weeks. If your dates are off and you are actually less than 6 weeks pregnant, it is possible that the heartbeat will not be detected until next week. The Ultrasound can be repeated in one week and can then determine if the fetus has a heartbeat.