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A 41-year-old member asked:

Is first ultrasound or the second more accurate?

1 doctor answer1 doctor weighed in
Dr. Amy Levine
Radiology 24 years experience
Ultrasound dating: The first. First trimester ultrasound is accurate within 5-7 days. 2nd trimester ultrasound has accuracy of +/_ 2 weeks. Lmp dating also assumes a 28 day cycle. There is no test that can date conception more accurately than a 1 week window. Due date is based on LMP unless us off by more than 1 week 1st trimester or 2 weeks in 2nd.
Created for people with ongoing healthcare needs but benefits everyone.

Similar questions

A 21-year-old female asked:

If i had my first ultrasound at 14w3d how accurate is that. _/+?

1 doctor answer1 doctor weighed in
Dr. Karen Dantin
Family Medicine 38 years experience
Ok: Earlier ultrasounds are considered most accurate for date determination.
Created for people with ongoing healthcare needs but benefits everyone.
Last updated Feb 13, 2015
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