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Doctor insights on: Ultrasound Accurate Dating

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Are ultrasounds accurate at dating conception at 12 weeks?

Are ultrasounds accurate at dating conception at 12 weeks?

Much more than: Later in gestation. First trimester ultrasound is most accurate at estimating gestational age within 5-7 days (depends on the center). It trails off after that. General rule: 2nd trimester scans for dating are +/- 14 days and 3rd trimester is the least accurate (+/-21 days). ...Read more

Dr. Michael Gabor
2,275 Doctors shared insights

Sonogram (Definition)

An ultraound, also known as a sonogram, is a painless and relatively inexpensive imaging test that utilizes sound waves instead of ionizing radiation. There are no side effects. Ultrasound can give us two-dimensional, and in some applications three-dimensional, images of structures and organs in virtually any part of the body. In addition to diagnostic uses, such as evaluating abnormalities in the abdomen, pelvis, and breast, ultrasounds are commonly used to guide needle and catheter placement in a variety of surgical ...Read more


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Are 11week ultrasounds accurate for dating? Margin of error?

Are 11week ultrasounds accurate for dating? Margin of error?

Varies: The range of error for an ultrasound at that point would likely be around +/- 8 days. ...Read more

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Are transvaginal ultrasounds accurate for dating at 4-5 weeks (only a sac was seen) and at 11 weeks?

Are transvaginal ultrasounds accurate for dating at 4-5 weeks (only a sac was seen) and at 11 weeks?

Yes: While the dating based on sac size is questionable, it is usually accurate to within a few days--depends on type of ultrasound. An ultrasound at 11 weeks, should be within one week. ...Read more

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Are transvaginal ultrasounds more accurate in dating than abdominal ultrasounds?

Are transvaginal ultrasounds more accurate in dating than abdominal ultrasounds?

Depends: On the size if the baby. Transabominally is fine as the baby increases in size. If it is really small then tv is bettet. ...Read more

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Are 11 week ultrasound more accurate for dating conception than 6 week ultrasound, both are transvaginal?

Are 11 week ultrasound more accurate for dating conception than 6 week ultrasound, both are transvaginal?

Not necessarily: Due dating pregnancies is more accurate with more than one ultrasound performed. However, the 6 week ultrasound might be more accurate in dating your conception. Either way ultrasounds have a 'fudge factor' of 1 to 2 weeks in determining accuracy. ...Read more

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Are abdominal ultrasounds just as accurate at dating pregnancies at 8 weeks as transvaginal?

Are abdominal ultrasounds just as accurate at dating pregnancies at 8 weeks as transvaginal?

Transvag better: Generally, transvag more accurate as you can get better views (usually). But if thin patient, experienced operator of the ultrasound and good views it can be very accurate. Best of luck. Dr R ...Read more

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Are abdominal ultrasounds as accurate for dating as vaginal around 11 weeks of pregnancy? What is the margin of error for abdominal at this gestation?

Are abdominal ultrasounds as accurate for dating as vaginal around 11 weeks of pregnancy? What is the margin of error for abdominal at this gestation?

Yes, if...: An abdominal ultrasound at 11 weeks is just as accurate for dating as vaginal (+\- 1 wk) if the image quality is good. You can see early fetal anatomy much better vaginally though. ...Read more

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How accurate are ultrasounds for dating pregnancy what's the margin of error. If my due date is oct 31, what are the dates I could have gotten pregnant?

What year?: It would seem that you would have to conceive on feb. 8, 2014 to give birth on 10/31. If the question is of historical interest, I would need to know when the ultrasound was done. Otherwise, you might want to check the dates you provided. ...Read more

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Are six week ultrasounds less accurate for dating a pregnancy than a eight week ultrasound?

Are six week ultrasounds less accurate for dating a pregnancy than a eight week ultrasound?

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. That said, there is some variable in the initial weeks. 8 wks is not necessarily more accurate for dating, but presence of a fetal pole and heart rate (which may not be seen at 6 wk) is more reassuring that the pregnancy is on track. ...Read more

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Is a 9 week or 20 week ultrasound more accurate for dating a pregnancy?

Is a 9 week or 20 week ultrasound more accurate for dating a pregnancy?

9wk: Early in the pregnancy the baby grows at a certain known rate. The 9wk sonogram is by far more accurate for dating. ...Read more

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My first ultrasound showed only a 9mm gest sac. 2 weeks later they could see the baby, measuring 7w1d. How accurate are these measurements for dating?

My first ultrasound showed only a 9mm gest sac. 2 weeks later they could see the baby, measuring 7w1d. How accurate are these measurements for dating?

Pretty standard.: Although there is usually some plus/minus variance in the measurement, these measurements have been established and standardized so they are pretty accurate. ...Read more

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How accurate are dating ultrasounds?

Depends: 1st trimester +\- 5 days
2nd tm +- 10 days
3rd tm +- 21 days. ...Read more

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Are 6 and 12 week ultrasounds just as accurate as 10 week ultrasound for dating purposes?

Unanswerable: There has to be more to this story. Why would any OB offer you three ultrasounds so very close together? Ob ultrasounds are thought to be most accurate early on. So, I would rely on the week six u/s first. But, your OB may have better specific information here. ...Read more

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I had ultrasound on 01/20/14, with the baby measuring at 4.8 cm, is this accurate for a dating of 11weeks 4 days fetus?

I had ultrasound on 01/20/14, with the baby measuring at 4.8 cm, is this accurate for a dating of 11weeks 4 days fetus?

Yes: Average length at this gestational age would be 4.1 to 5.4, so your baby definitely falls within that range. Good luck! ...Read more

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Ultrasound accuracy? I had an ultrasound that dated me at 13 weeks and 3 days. How accurate would this dating be. Could it be two weeks off?

Yes: Ultrasound dating accuracy is best in the first trimester. After that, ultrasound dating is less accurate. Here is a link which may help you: http://www. Ultrasoundcare. Com. Au/services/pregnancy-ultrasound-5-17-weeks-dating-and-viability. Html. ...Read more

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I have a question about a dating ultrasound? How accurate are they? The dating based on my LMP and the date it puts me at are 10 days apart

I have a question about a dating ultrasound? How accurate are they? The dating based on my LMP and the date it puts me at are 10 days apart

1st trimester: If your dating ultrasound is in the 1st trimester, most doctors, if the ultrasound is off by > 5 days of lmp, will use the ultrasound as has more accuracy. Hope that helps your question! ...Read more

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I had a 6 week ultrasound and 11 week for dating purposes, they were both high quality and put my conception on or about december 6, how accurate?

Excellent: The most accurate ultrasounds for dating a pregnancy are those done in the 1st trimester, which both of these scans were. A 6 week ultrasound can sometimes be a little early, depending on the size of the crown-rump-lenth, so getting another one at 11 weeks is great! The fact that these 2 ultrasounds agree means that you have very accurate dating. Good luck with pregnancy! ...Read more

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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

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Had a dating ultrasound I was 14w3d. Couldn't use LMP I was on depo, I wasn't having periods. Can edd be off by 2w3d at 14 week ultrasound. How accurate?

Had a dating ultrasound I was 14w3d. Couldn't use LMP I was on depo, I wasn't having periods. Can edd be off by 2w3d at 14 week ultrasound. How accurate?

Unlikely: 14 week ultrasound is on the cusp between first and 2nd trimester. First trimester ultrasound usually accurate to 3-5 days. Second trimester accurate to 1-2 weeks. So at 14 weeks I would doubt the dates would be 2w3d off. This would be more likely in the third trimester. ...Read more

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I had dating ultrasound at 20 weeks (less accurate) giving me a due date of 9/6/13. Is it possible for father to be someone I had sex with 11/23/12?

I had dating ultrasound at 20 weeks (less accurate) giving me a due date of 9/6/13. Is it possible for father to be someone I had sex with 11/23/12?

I am not sure.: Using: http://calculatorgo. Com/conception-date. Php? Month=9&day=6&year=2013 which is a conception calculator your estimated conception date was 14 december 2012 (between 12 to 17 december 2012). ...Read more

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How accurate are transvaginal ultrasounds in dating conception date if have irregular periods?

How accurate are transvaginal ultrasounds in dating conception date if have irregular periods?

Most Accurate: Transvaginal ultrasound is the most reliable way to determine a pregnancy due date. When done early, it can date a pregnancy within a few days and is more accurate than determining a due date of the last menstrual period. ...Read more

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My dr told me they DO NOT add 2 weeks on the dating ultrasound. What does that mean?

My dr told me they DO NOT add 2 weeks on the dating ultrasound. What does that mean?

2 wks. Added already: If the doctor says not to add 2 weeks to the number estimated by the ultrasound, that means the number already includes the 2 weeks. That means the number is the "number of week pregnant" the woman is, on the day of her ultrasound. (if the number did not already have the 2 weeks added on, then the number would be the "age of the fetus", which is 2 weeks less than the "number of weeks pregnant") ...Read more

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