Related Questions

How often are first trimester ultrasounds off in dating conception?

Off? Depends what you mean by 'off.' the theoretical accuracy of a 1st trimester us is considered to be +/- 2-3 days, so in that sense they are always 'off.' if you mean wrong, as in more than 2-3 days, no one knows this - but with a skilled sonographer and a current us machine, it shouldn't be off by more than a few days very often. Read more...

I wanted to know how accurate early ultrasounds (first trimester) are in conception dating? If I was 5 weeks4days 9/23/13 putting conception 25-28 of aug could I have still concieved 7/28/13

No. An ultrasound at 5 weeks is extremely accurate. It is impossible for you to have conceived in july. Read more...
Very accurate. Provided that the individual sono graphed is reliable.;the earlier sonograms are usuall more accurate. Read more...

What does it mean when LMP dating by ultrasound in first trimester assumes a 28 day cycle?

Family practice . It is an u/s to determine normal growth and determine proper due date if unsure of lmp. Usually done at 18 weeks gestation. Read more...

Is u/s dating in first trimester more accurate that going by LMP? EDD changed & going by ultrasound now...

Depends. 1st trimester US is accurate within 5-7 days so if it differs from your LMP due date by more than that then the US is used. Also if you are uncertain about your LMP, most OB's will use that early US. Read more...