gestational sac size vs. crown rump length for due date?

[jojoq102]

I need help understanding my latest ultrasound.

I have already had issues leading up to this point (low hcg and not doubling correctly)

At 5.1 weeks the ultrasound showed a gestational sac and a yolk sac. We were given a due date of Jan. 10th.

At 6.6 weeks we saw a heartbeat of 112 bpm and due date changed to Jan. 12

At. 7.3 weeks hearbeat went up to 126 bpm but due date changed again to Jan 13th!

The person doing the ultrasound said that the date change (losing 3 days) was not a good sign.

When I asked the Dr. he said he was not concerned about the due date changing because that was measuring the gestational sac and the embryo (I guess that means the crown to rump length) is still on target.

Does this make sense to anyone? I have found info. on the internet that says a small gestational sac is not good. Is that only earlier in the pregnancy? Any info. would help thanks!

[marya]

First, remember that due dates are arbitrary. Your baby will show up when he/she is good and ready

Second, u/s dating is not precice at all. If the crosshairs on the monitor are off by a mm, your dating can change dramatically at this point. Generally a u/s had a margin of error of about one week, which you are well within. More importantly is sustaining a strong heart rate.

Good luck!!

[BC-DKNY]

i agree with marya. i was upset when they said i was measuring 6 days behind with my ds. and there was no question about when i O'd. however the window for implantation is 6-12 dpo. so without actually knowing when you implanted you can't "assume" the measurements are right or wrong.

as marya said, there's a margin for error in either direction of a week. it's especially difficult to get a precise measurement this early on in pg. try not to worry too much. they can only be as accurate as the equipmemt they're using is.

best wishes...

[dee32]

I was told by the high risk doctor that to be 10 days behind or ahead is perfectly normal and with so many u/s in the beginning it will tend to change. My friend's sister going to an RE is going through that now because she goes for a u/s every week and they keep moving her due date but she is over 8 weeks now and everything is looking good.

[TaraDF]

when i went for my 12w u/s and they "dated" the fetus, the acceptable dates (as shown on the video I have) were from 11w2d to 13w5d & I was 12w4d (baby msrd 12w3d).
I would not worry about it if your Dr is not concerned.
I have a slight idea of when I o'd & knew exact my LMP. My Dr's date matches that of my LMP, so i'm not going to argue.