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A 29-year-old female asked:

Can a 5 week ultrasound be off by a week or more like a couple days?

3 doctor answers3 doctors weighed in
Dr. Addagada Rao
General Surgery 57 years experience
Possible few days: Radiologist , interprets pretty accurately , may be off by few days not few wks, as the embryo will follow the clock like pattern , end of 4 , beginning of 5 wk you see gestational sac and fetal pole, speak to your doctor who has more information, good luck.
Dr. Amy Levine
Radiology 24 years experience
Ultrasound dating: First trimester ultrasound is accurate within 5-7 days. There is no test that can date conception more accurately than a 1 week window.
Dr. Joseph Accurso
Radiology 30 years experience
Ultrasound +/- 8%: Properly performed and interpreted ultrasound examinations have a variability of 8% plus or minus the measured dating. Given the dates in the question and assuming a high-quality ultrasound, i would suspect that last menses dating is inaccurate. Ultrasound dating at 5 weeks 0 days should have a 95% confidence range of 4 weeks 4 days to 5 weeks 3 days which is +/- 8%.

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Had to dating ultrasound before 12 weeks are they accurate to within a couple days?

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A 33-year-old member asked:

What can be seen on an ultrasound at 5 weeks?

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Dr. Grant Linnell
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Gestational sac: Typically, only a small fluid filled sac is seen in the endometrial canal at five weeks. It is not typical to visualize any fetal tissue at this time.
A 48-year-old member asked:

What can be seen on a 5 week ultrasound?

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Dr. Grant Linnell
Radiology 25 years experience
Gestational sac: Typically, only a small fluid filled sac is seen in the endometrial canal at five weeks. It is not typical to visualize any fetal tissue at this time.
Last updated May 6, 2015

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