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Doctor insights on: Ultrasound Due Date

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How accurate is an ultrasound due date estimate?

How accurate is an ultrasound due date estimate?

Best on earlier u/s: Ultrasounds use composite data obtained during the exam to determine an EDD (estimated date of delivery). This date will also have a +/- number of days giving an accuracy range. First trimester ultrasounds are accurate to within about a week, second trimesters estimates are accurate within about 2 weeks, and third trimester scans about 3 weeks. ...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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Can an ultrasound due date be off by 1 week 4 days?

Can an ultrasound due date be off by 1 week 4 days?

Due date estimation: The estimation of due date can be based on lmp or ultrasound. If the ultrasound due date was performed in the first trimester and the difference is more than 5days from lmp based due date, the most accurate should be due date based on ultrasound. In your case, it is 11days and therefore should use ultrasound due date if done in first trimester. Good luck. ...Read more

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Is ultrosound due date correct or LMP date.... Confuse they like a week diff LMP due dat may122013 and ultrasound due date may 252013?

Is ultrosound due date correct or LMP date.... Confuse they like a week diff LMP due dat may122013 and ultrasound due date may 252013?

Accuracy varies: The accuracy of ultrasound varies depending on when in pregnancy it is done. Generally +/- 1 week in first trimester, +/- 2 weeks in second trimester. If there is a discrepancy in your recall of LMP and the ultrasound results, most doctors will go with the ultrasound results. ...Read more

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So everyone says early ultrasounds are more accurate then LMP so mine has 4 day difference between edd so should I not go by ultrasound due date?

So everyone says early ultrasounds are more accurate then LMP so mine has 4 day difference between edd so should I not go by ultrasound due date?

Within 4 days is: No real difference. There is nothing magical about either date, except for 2 things:

1. If the LMP is different from the early OB us dating by more than 2 weeks, the LMP is probably wrong.

2. What everyone wants to happen is appropriate interval growth - meaning the fetus grows in size to match the time since the last us - that means growth is happening normally. ...Read more

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Before ultrasound due date was 07/13/15 but after ultrasound due date went to 07/27/15 which is more accurate?? . Took preg. Test 11/08 it was neg.

Before ultrasound due date was 07/13/15 but after ultrasound due date went to 07/27/15 which is more accurate?? . Took preg. Test 11/08 it was neg.

Depends: It depends on when ur ultrasound was done whether it or ur dates r more accurate. The margin of error for ultrasound dating increases as the pregnancy progresses. The first month all fetuses r pretty much the same size but by delivery babies can vary quite widely in size (normal is 5 1/2 pounds to 8 pounds at term).If the ultrasound was done early, it is more reliable. If done late, your dates are. ...Read more

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How do you work out conception date from ultrasound due date?

How do you work out conception date from ultrasound due date?

Calculator: Using a reverse due date calculator, you can enter the estimated due date and the calculator will determine the likely date of conception based on average lengths of menstrual cycles and pregnancies. ...Read more

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If my LMP was 9th sept but I didn't ovulate til 4 weeks later, will dr still use my LMP or my ultrasound due date?

If my LMP was 9th sept but I didn't ovulate til 4 weeks later, will dr still use my LMP or my ultrasound due date?

Depends: Your OB will decide based on certainty of your clinical dates. Not sure how you know when you ovulated. Due date is usually determined based on lmp, because it is generally difficult to know exactly when ovulation occurs. If an early dating ultrasound differs by more than a week or so and/or if clinical dates are uncertain, your OB may choose to use a due date based on the ultrasound instead. ...Read more

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Should go by ultrasound due date of March 20th instead of lmp date of March 7th? Hcg 105 July 13th but no sac. Sac finally July 20th measuring 5 weeks

Should go by ultrasound due date of March 20th instead of lmp date of March 7th? Hcg 105 July 13th but no sac. Sac finally July 20th measuring 5 weeks

Ultrasound date CRL: Ultrasound date from crown rump length (CRL), will be best way to assign due date,
gestational sac, not as good ...Read more

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Have had 2 transvaginal ultrasounds. Due date has changed twice. Due date is now 5/1/16. LMP was 7/12/15. Confused on conseption date??

Have had 2 transvaginal ultrasounds. Due date has changed twice. Due date is now 5/1/16. LMP was 7/12/15. Confused on conseption date??

Due dates & sonogram: Sonograms are only an approximate estimate of due dates. Due dates are also approximate but become more accurate as the pregnancy progresses and more parameters (landmarks) can be utilized to make that determination. Since your dates have been changed twice, your conception date may be difficult to ascertain. ...Read more

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My last period was march 13. 8 week ultrasound due date dec 21.Postive test at april 11 intercourse 28th and april4.is it possible this is from the 4?

My last period was march 13. 8 week ultrasound due date dec 21.Postive test at april 11 intercourse 28th and april4.is it possible this is from the 4?

Too close to know: That 1 week difference in timing of intercourse too close together to tell via ultrasound at 8 weeks which date of intercourse is likely to have resulted in conception. I am assuming this is a question of paternity of the baby. Unfortunately that will have to wait until the baby is born and testing is done on both potential fathers and the baby. Sorry. Best of luck with your pregnancy. Dr. R ...Read more

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16w & 3d had ultrasound due date may18 last period aug10. Had sex july26 and many times in aug each month with different person. When did I get preg?

16w & 3d had ultrasound due date may18 last period aug10. Had sex july26 and many times in aug each month with different person. When did I get preg?

Can't tell for sure: You are not going to be able to tell this for certain with the data you presently have. Ultrasound has a accuracy of about 7-10 days either way. In other words if the ultrasound says you are 16 weeks 3 days you could be as little as 15 weeks, or as much as 17.5 weeks. The dates are too close together to know for certain by dates of intercourse and ultrasound. ...Read more

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MY ULTRASOUND DUE DATE IS SEPTEMBER 8 WHEN DID I GER PREGNANT?

MY ULTRASOUND DUE DATE IS SEPTEMBER 8 WHEN DID I GER PREGNANT?

Conception: Conception calculators are all over the web. You can play with them yourself. For your pregnancy sex occurred somewhere between 12/11/2013 to 12/16/2013. ...Read more

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Sex that got my friend pregnant with ultrasound due date of nov. 30?

Unanswerable: I am sorry, but there is nothing in this statement that gives me a clue as to what you are really asking. If you are concerned, ultrasounds early in pregnancy are the most accurate predictors or when conception occurred and when to set the estimated due date. ...Read more

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Ultrasound due date is june 16th! Any chance that protected sex on october 5th got me pregnant?

Ultrasound due date is june 16th! Any chance that protected sex on october 5th got me pregnant?

U should have: Conceived about 9/24 or 9/25 if your cycles are every 28 days if your cycles are longer than it is possible but not probable for 10/5. ...Read more

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If my ultrasound due date is 4/19/13 and my ave. Cycle is 27 days and my last period was 7/14/12, is it possible that I got pregnant on 7/30 or 7/31?

If my ultrasound due date is 4/19/13 and my ave. Cycle is 27 days and my last period was 7/14/12, is it possible that I got pregnant on 7/30 or 7/31?

Impossible: It is impossible to date a conception with that level of precision; if a paternity issue than difficult situation. You may need to consider dna after the baby is born to determine and figure out who you were having sex with the week prior to conception. Sperm lives for about 7 days and is generally there awaiting the ovum which survives 12-24 hours. It's not who you had sex withthe day of conce. ...Read more

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I had implantation bleeding on Aug 25th. I countback conceived Aug 15th. Ultrasound due date May 1st Could I still conceive on15th with that duedate?

I had implantation bleeding on Aug 25th. I countback conceived Aug 15th. Ultrasound due date May 1st Could I still conceive on15th with that duedate?

Conception: A May 1st due date would correlate (assuming 28 day cycle). actually would be more likely around August 8th. LMP of 7/25 give's due date of 5/1. Perfect 28 day cycle ovulation would be around 14 days after 7/25. But all this is approximation. Implantation bleeding often times does occur around the time of expected LMP, so 8/25 makes sense. 1st trimester US is accurate within 5-7 days though ...Read more

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Your ultrasound due date should always correlate with your last menstrual period, correct?

Your ultrasound due date should always correlate with your last menstrual period, correct?

No.: Ultrasound dates depend on fetal size. If ovulation occured at other than 14 days after first day of last menses some discrepency will exist. That being said, ultrasound size based due date estimates are only accurate to about a week in the first, two weeks in the second and three weeks in the final trimester of pregnancy. ...Read more

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Embreo transfer or ultrasound is due date more accurate?

Embryo transfer: Embryo transfer would be the ultimate gold standard for gestation age. The number of days since conception of the transferred embryo (3-5 days) would be known so the precise time of conception would be available so the estimated due date could be more precisely estimated. ...Read more

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My doctor said b/c my baby was small at my 21 week ultrasound, my due date changed from may 31 to june 16. How accurate are these estimates?

My doctor said b/c my baby was small at my 21 week ultrasound, my due date changed from may 31 to june 16. How accurate are these estimates?

You said it: Estimate. These values are based on measurements of the baby and have a variation depending on how far along the pregnancy you are. Towards the end there could be a three week range of delivery dates. It is always best to talk openly with your doctor ...Read more

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What do you suggest if my doctor said b/c my baby was small at my 21 week ultrasound, my due date changed from may 31 to june 16. are they right?

What do you suggest if my doctor said b/c my baby was small at my 21 week ultrasound, my due date changed from may 31 to june 16. are they right?

Ultrasound dating: First trimester ultrasound is accurate within 5-7 days. Lmp dating also assumes a 28 day cycle. Due date is based on LMP unless us off by more than 1 week 1st trimester or 2 weeks in 2nd. And it's only an estimate; the baby will decide when to come regardless of what you or your doctor think :). ...Read more

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I don't remember my lmp. According to ultrasound my due date is oct 10th...Around what time did I concieve?

I don't remember my lmp. According to ultrasound my due date is oct 10th...Around what time did I concieve?

When was scan done?: Accuracy of ultrasound varies from 3 days to 2-3 weeks depending on when it was done. Plus the date of sex can be around not always on the suspected date of conception. The date of pregnancy test and size of the uterus during first pelvic can also help determine the approximate date. So, to avoid misunderstanding, it is best to ask the OB performing the first pelvic and ultrasound if mid-january. ...Read more

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Nursing mum, my LMP was on june 4th. July 4th I got psv pgn test but it was very faint line. Ultrasound showed due date on april 1st! 4 weeks behind? Why?

Nursing mum, my LMP was on june 4th. July 4th I got psv pgn test but it was very faint line. Ultrasound showed due date on april 1st! 4 weeks behind? Why?

Delayed ovulation: While nursing, menstrual cycles and ovulation often become irregular. This makes it diifficult to date a pregnancy by your lmp. Ovulation occurred 4 weeks after expaected and the menses may not have been a normal period. ...Read more

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How accurate are ultrasounds in determining due date?

How accurate are ultrasounds in determining due date?

Depends on dates: The ultrasound (us) is the most accurate way we have of deciding how pregnant you are. There is a variation in us accuracy due to how we measure and who is measuring, but the accuracy is about 3-4 days before or after the measured size until about 10 weeks, plus or minus a week to about 14-15 weeks, then gradually changing up to a 3 week range in the last 2 months of pregnancy. ...Read more

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If I'm measuring 2 days ahead at a 20 week ultrasound should my due date change?

If I'm measuring 2 days ahead at a 20 week ultrasound should my due date change?

Definitely not: You never change a edd (due date) based on a second trimester ultrasound if you had reliable first-trimester dating. The ultrasound gets less precise as the pregnancy goes on. ...Read more

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Is my 8 weeks and 3 days ultrasound my actual due date? It was 10 weeks and 3 days before ultrasound

Is my 8 weeks and 3 days ultrasound my actual due date? It was 10 weeks and 3 days before ultrasound

Yes: If your US said 8 weeks 3 days and your LMP said 10 weeks 3 days, then that is more than 7 days difference and the US due date would be used. ...Read more

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Last cycle 1/1, due date 10/8. 1st ultrasound at 7wks. Due date moved back to 10/13 bcuz baby size. Possible reasons why?

Last cycle 1/1, due date 10/8. 1st ultrasound at 7wks. Due date moved back to 10/13 bcuz baby size. Possible reasons why?

See Below...: An ultrasound at 7 weeks is very accurate for dating pregnancy. Using the first day of the last menstrual period is less reliable for a variety of reasons. For example, it assumes that you ovulate on cycle day 14. Some women ovulate earlier or later. Best wishes! ...Read more

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Does zooming in on an ultrasound affect the due date given? And can a 7 week fetus be mistaken door a 9 week fetus?

Does zooming in on an ultrasound affect the due date given? And can a 7 week fetus be mistaken door a 9 week fetus?

No: Zooming in does not affect measurements, the machine accounts for the zooming in. Ultrasound dates based on measurement. It is the most accurate way to date a pregnancy if done in first trimester. ...Read more

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Are transvaginal ultrasounds accurate concerning due date?

Are transvaginal ultrasounds accurate concerning due date?

Yes: Transvaginal ultrasound is usually done in the first trimester (12 weeks). Generally, early ultrasounds are more accurate for dating. Than late ultrasounds. ...Read more

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