Top
30
Doctor insights on: What Is More Accurate To Measure Pregnancy Lmp Or Ultrasound

Share
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


4

4
My LMP was nov 24 indicating I'm 7 weeks. Vaginal ultrasound measures I'm 5w5d and hCG is 75, 0000. What does this mean?

My LMP was nov 24 indicating I'm 7 weeks. Vaginal ultrasound measures I'm 5w5d and hCG is 75, 0000. What does this mean?

Sounds normal: The variation of dates between LMP and ultrasound is very small (ultrasound considered more accurate). Without other concerns it sounds like a normal early pregnancy. ...Read more

8

8
Hi doctors I had a ultrasound yesterday it said due aug 29 what is more accurate LMP or ultrasound I need my most accurate conception date please help?

Hi doctors I had a ultrasound yesterday it said due aug 29 what is more accurate LMP or ultrasound I need my most accurate conception date please help?

Depends: Your last menstrual cycle would be the most accurate if you ovulated approximately day 14. Ultrasounds further on into the pregnancy are less accurate. ...Read more

9

9
How well is conception date accuracy with ultrasound at 12 weeks? My LMP started on nov.28, 2011 lasting five days. I had an ultrasound on jan.17, 2012 counting me at 7 weeks and 1 day, then another ultrasound on feb.21, 2012...Counting me at 12 weeks exa

How well is conception date accuracy with ultrasound at 12 weeks? My LMP started on nov.28, 2011 lasting five days. I had an ultrasound on jan.17, 2012 counting me at 7 weeks and 1 day, then another ultrasound on feb.21, 2012...Counting me at 12 weeks exa

The: The ultrasound dating now is remarkably accurate. There can be discrepancies in the dates that the patient has from the date of menstrual period, but the ultrasound dating is remarkably accurate based on the "crown rump length" of the fetus, which is the measurement of the baby from the crown of the head to the tip of its bottom, the development of the heart, and other vital organ which can already be identified by ultrasound dating. A 12 week ultrasound date should be very accurate. ...Read more

10

10
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

11

11
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

13

13
Is early ultrasound at 8w1d more accurate at predicting conception than LMP? EDD changed going by ultrasound now too...

Is early ultrasound at 8w1d more accurate at predicting conception than LMP? EDD changed going by ultrasound now too...

Possibly: Ultrasound done early is much better than LMP dating for the "Expected date of Delivery." Conception is another issue entirely. Usually conception occurs 2 weeks prior to a missed LMP, but this is ONLY an estimate. Conception dating is not something that is useful in medicine and there is too much variability to do that kind of dating, Unless you are an In Vitro (IVF) pt. Then you know for sure. ...Read more

14

14
Which gestational age is more accurate, LMP based or ultrasound one? By LMP I am 27weeks and 4 days. Ultrasound says 28 weeks

Gestational age: Your LMP is usually more accurate than ultrasound especially at 27+ weeks. Ultrasound is more accurate in the first trimester and gets less accurate the further along you get in the pregnancy. ...Read more

15

15
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

16

16
The doctors determined my due date from an estimated lmp, it was nov4. Sept 16, I got an ultrasound that read oct25 which date is accurate?

Probably LMP: Did you have a 1st trimester ultrasound? If you did, that would be the most accurate, especially if it was consistent with your LMP. A third trimester ultrasound is less accurate, with an error range of 2-3 weeks. The ultrasound would therefore be consistent with your dates based on your LMP, since there is only a 10 day difference. ...Read more

17

17
Don't need to pinpoint conception day, but two first trim ultrasound give same due date we have no lmp to go off, how accurate is age of our baby?

Don't need to pinpoint conception day, but two first trim ultrasound give same due date we have no lmp to go off, how accurate is age of our baby?

Accurate estimates: Ultrasound dating scans in the first trimester, such as at 8-11 weeks of pregnancy, are very accurate... meaning plus or minus one week. Especially if the doctor feels the fetus is growing appropriately for gestational age through the course of the pregnancy, the original dating estimates were likely very accurate. ...Read more

18

18
Fetus measures one week ahead. When I can say that I reach the viability? When baby measures 24 weeks on ultrasound or when I am 24 weeks past LMP?

Fetus measures one week ahead. When I can say that I reach the viability? When baby measures 24 weeks on ultrasound or when I am 24 weeks past LMP?

Older than 26 weeks: Date a pregnancy is not pinpoint accurate. It is only a ballpark figure giving your a date to expect the baby to deliver. Viability of the fetus will depend on how well the fetus develops. Generally the best chance to survive is at term. At 26 weeks and older there is at least a chance ...Read more

20

20
Ultrasound accuracy at 13 weeks an 3 days I was just wanting to know the number of days an ultrasound could be off at that point would it be off by 14 days? And also my LMP was 10/27/2011 due 08/02/2012 but the ultrasound said LMP 10/18/2011 due date 07/2

Ultrasound accuracy at 13 weeks an 3 days I was just wanting to know the number of days an ultrasound could be off at that point would it be off by 14 days? And also my LMP was 10/27/2011 due 08/02/2012 but the ultrasound said LMP 10/18/2011 due date 07/2

Ultrasound: Ultrasound accuracy at this stage of pregnancy is very accurate. The dates from ultrasound are determined by the size and development of the fetus and are very accurate. The dates on ultrasound are usually much more accurate than going by the date of last menstrual period. ...Read more

21

21
So are ultrasounds more accurate in the first trimester at 8w1d? And should I trust if I know my LMP & doctors change EDD going by u/s now??

First trimester u/s: The earlier an ultrasound is done, the more accurate it is. An ultrasound done at 8weeks and 1 day is probably a day or two off. This is the reason for assigning a due date based on your early ultrasound. It is probably only a day or two off. Remember, a due date does not mean that you will deliver right on that day. ...Read more

22

22
I'm due november 7th, according to 11 week ultrasound. I had about 30 day cycles, but I couldn't remember lmp. When did I conceive? And how accurate?

Something wrong: Something about your question is wrong. To have a due date of november 7th you would only be one or two weeks now. ...Read more

23

23
How accurate are ultrasounds @ 6 weeks? My due date is august 29th according to ultrasound yesterday my LMP was nov 18 when did I conceive? Please? :)

How accurate are ultrasounds @ 6 weeks? My due date is august 29th according to ultrasound yesterday my LMP was nov 18 when did I conceive? Please? :)

Very good: Ultrasound gets less accurate as the fetus ages. At this point, dating is pretty accurate.

You conceived on or about nov 23rd. ...Read more

24

24
How accurate are ultrasounds at 12 weeks? On march 4 I was told 13w when I should've 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 should've 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

25

25
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

27

27
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

28

28
Do ultrasounds add two preconception weeks when measuring baby? If baby measures 12 w is this supposed to date to LMP or conception?

Yes. LMP.: The gestational age (number of weeks pregnant) stated in the result of the ultrasound already added the 2 preconception weeks. If the ultrasound dating says 12 weeks gestation, that means 12 weeks since the estimated start of the last menstrual period (lmp). ...Read more

29

29
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

Dr. Oscar Novick
4 Doctors shared insights

Pregnancy (Definition)

When your due date arrives, you will be more than ready to have your baby! Most women deliver the baby somewhere between 37 and 42 weeks. According to the American College of Obstetricians and Gynecologists, only 5% of babies arrive on the exact due date. Approximately 7% of babies are not delivered by 42 weeks, and when that happens, it is referred to ...Read more