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Ultrasound accuracy
I am wondering how accurate transvanginal ultrasounds are? and if it is possible for them to be off by a whole month? or if it is even possible for a fetal heart beat to be dectected at 4 weeks? please help me out because i am not sure when i exactly ovulated and i really question the doctors estimates.
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1538784 tn?1298788674
It is possible but they go by size of the baby to say how far along you are so they could easily be off.
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1439241 tn?1306304111
Hi, my doc did the trasnvaginal ultrasound twice - 4 wks apart & both during my 1st pregnancy & 2nd pregnancy - both showed that my due date is 3 days later than what my "calculated" ovulation time showed us - we never heard the heart beat of our 1st baby not at 5 wks & not at nearly 9 wks - we lost the baby ... we got pregnant immediateley there after - we had a heartbeat at 8 wks and at 12 wks - I waited specifically until I was 8 wks before I went to the doc the 2nd time - I read on a few websites that you will be hearing the heartbeat at 5 - 6 wks ... I just did not want to go though the same thing as with the 1st pregnancy.
Good luck & God Bless
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1278093 tn?1294323984
it's very uncommon to see the heartbeat until at least 6 weeks and many don't see it until closer to 8 weeks.  we were lucky enough to see it at 6 weeks 3 days.
the measurements in the first 12 weeks are very accurate actually, it's later ultrasounds that dating becomes very inaccurate.
we had IVF and so we know exactly when the embryo fertilized, etc.
my 6 week and 8 week US measurements were exactly correct (to the day)
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A transvaginal ultrasound when performed during the first trimester of pregnancy can generally date pregnancy within about 1 week.

Heart beat typically wont be detected until 6 weeks gestation.
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My doctor sow a yolk sac at 3 weeks and the baby heart @  4 weeks
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377493 tn?1356505749
Transvaginal ultrasound in first trimester is typically very accurate. It's later stages that baby grows at his/her own pace, so dating is not recommended by ultrasound any longer.  

As for heartbeat at 4 weeks...it does happen, but typically a heartbeat is first seen between 5 1/2 and 6 1/2 weeks.  
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