A 20-year-old female asked:
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iwent tothe doctor on september24 had a transvaginal ultrasound done.they determined i was9w4d. so about a 10-11w gestational period.how off can thy b?

2 doctor answers
Dr. Olivia Liao
31 years experience Ophthalmology
Margin of error: There is a margin or error on ultrasound dating: http://www.Medscape.Com/viewarticle/703501_3.
Answered on Dec 10, 2013
Dr. Dennis Higginbotham
30 years experience Obstetrics and Gynecology
+/- about 7 days: An ultrasound at 9 weeks 4 days is generally going to be accurate to within about 7 days. So that person should be between 8 weeks 4 days and 10 weeks 4 days.
Answered on Oct 3, 2013

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