Accuracy of Early Ultrasound Scan

Jane Foley's picture

QUESTION

Hello! I Was hoping for your opinion regarding ultrasound and conception dates. Is it at all possible that my first ultrasound indicating 8weeks 5days on November 3rd and a second ultrasound on November 29th indicating 12weeks5days could in any way be corresponding with conception on or after October 1st?

My periods are irregular, so I'd feel better scientifically going through the possibilities.

Thank you!

ANSWER

Hello,
If you had an ultrasound on November 3rd showing you were 8w 3d the estimated conception date would be approximately September 17th.

If you had an ultrasound on November 29th showing you were 12w 5d the estimated conception date would be approximately September 16th.

Both of your ultrasounds show the same results. The error ratio is not more than a week this early in pregnancy. This means an ultrasound is quite accurate in the first trimester. I would think you most probably conceived well before October 1st.

Please note that a paternity test is the only way to tell for sure. If you are always going to wonder, please go ahead and do the paternity test for your own piece of mind.

With regards,
Jane Foley RDMS