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Doctor insights on: Is Your Lmp Or Ultrasound Most Accurate

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Dr. Michael Gabor
2,194 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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How do you know if your due date is accurate? (ultrasoud, multiple ultrasounds give same date, lmp, etc?)

How do you know if your due date is accurate? (ultrasoud, multiple ultrasounds give same date, lmp, etc?)

Pregnancy dating: The best dating is an accurate last menstrual period date confirmed by an early ultrasound. But not many women have that. Second best is an early ultrasound dating. Remember a term pregnancy is 40 wks +/- 3 weeks. Your due date doesn't mean you will deliver on that date. It's just a means of knowing how pregnant you are. ...Read more

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How accurate are ultrasounds at 12 weeks? On march 4 I was told 13w when i shouldve been 12w based on LMP. She said it could a week off

How accurate are ultrasounds at 12 weeks? On march 4 I was told 13w when i shouldve been 12w based on LMP. She said it could a week off

Fairly accurate: in general when approximating due dates the earlier the ultrasound the better and most accurate, if you had normal periods prior to pregnancy, i would use your due date from you lmp. further investigation is usually warrent at 12 weeks if your us edc is more than 1.5 weeks difference than the lmp on us at 12 weeks, good luck ...Read more

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If LMP and 12 week ultrasound correlate, would the u/s be considered more accurate since the LMP is known? Or is there still 1 week margin of error?

If LMP and 12 week ultrasound correlate, would the u/s be considered more accurate since the LMP is known? Or is there still 1 week margin of error?

LMP for dating : If in the first trimester, we go with the lmp unless the sono is over a week off. I we give the ultrasound date, but say "consistent with dates" the and still use the lmp date. ...Read more

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Is conception more accurate based off LMP or 9 week ultrasound?

Both is best: The most accurate dating is where the 1st trimester ultrasound is within a week of the lmp dating; that confirms the lmp dating. If the 9 week ultrasound gives dates greater than 1 week from what's predicted by the lmp then the lmp is not accurate and the ultrasound dating should be used. ...Read more

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How accurate/reliable is a LMP by ultrasound if the patients LMP was unknown?

How accurate/reliable is a LMP by ultrasound if the patients LMP was unknown?

Pregnant?: I assume you are pregnant. Early transvaginal ultrasound is very accurate and giving a proper gestational age for you pregnancy. From that age a due date is given and an "lmp" date is given even though you may not have actually had a menstrual cycle at that time. ...Read more

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I don't remember my lmp. My 12w4d ultrasound dated it. How accurate is that date? It's very important.

I don't remember my lmp. My 12w4d ultrasound dated it. How accurate is that date? It's very important.

Usually accurate: The earlier in your pregnancy the ultrasound was performed, the more accurate it will be at estimating your due date. US before 12 weeks is usually accurate to within 1-2 days. It is important to know how far along you are so that screening studies are performed at the correct time. It is also important to know how far along the baby is in case it comes early or there are issues with the pregnancy ...Read more

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My due date based on a 7w1d ultrasound is Sep. 2nd but my LMP is Aug. 13th. Which due date is more accurate.

My due date based on a 7w1d ultrasound is Sep. 2nd but my LMP is Aug. 13th. Which due date is more accurate.

Ultrasound: Generally speaking, a first trimester ultrasound is more accurate. If the two dates are within a couple of weeks, generally you keep the LMP dates. However, farther apart than that, you shift to the ultrasound dating because of its increased accuracy.. ...Read more