I'm new to the group. I had my first ultrasound on October 9th. I measured 5 weeks and 5 days (no heart beat detected) . I had a second ultrasound today (13 days later) and measured at 6 weeks and 2 days. There was a large sac with a yolk sac inside, BUT no heart beat detected. Has this happened to anyone, what was your outcome? I have no cramping or bleeding and my boobs are sensitive. No nausea though. I'm so worried. Could the first ultrasound be off on measurements? I'm not sure when my last period started which makes matters worse. Any insight is appreciated.