Doctor insights on:
Ultrasound Accurate Dating
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
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
Varies: The range of error for an ultrasound at that point would likely be around +/- 8 days. ...Read more
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
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
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
Why is it better to wait until 8 week gestation versus seven weeks gestation in order to have an accurate dating ultrasound?
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
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
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
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
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
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
Ultrasound dating accuracy? An ultrasound at 13 weeks and 3 days would have how many days error tops?
Depends: Assuming the tech measured accurately, probably not more than 3 days. ...Read more
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
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
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
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
October31 I had an ultrasound dating me at 6weeks+5 november20 I had another dating me at 9weeks+6 (2daysahead) when did I become preg? & how accurate?
9/28: The best estimate for your conception date would be 9/28/13. Hope that helps! ...Read more
Unlikely: This early more likely accurateGet a more detailed answer ›
I've had several ultrasounds all dating me within a few days of each other now at 7w gestation. How accurate is this when dating conception time?
I wanted to know how accurate early ultrasounds (first trimester) are in conception dating? If I was 5 weeks4days 9/23/13 putting conception 25-28 of aug could I have still concieved 7/28/13
Very accurate.: Provided that the individual sono graphed is reliable.;the earlier sonograms are usuall more accurate. ...Read more
Should be accurate: Within about 4-5 days either way.Get a more detailed answer ›
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
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
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
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