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Doctor insights on: Error Ultrasound

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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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What is the margin for error of an ultrasound at 15 weeks? Preg confirmed at about 11 wks, wouldn't US have been done then?

What is the margin for error of an ultrasound at 15 weeks? Preg confirmed at about 11 wks, wouldn't US have been done then?

Fetal Ultrasound: An Ultrasound may be done prior to 18-21 weeks gestation if a patient is unsure of her dates or there is a question of whether the pregnancy is within the uterus and not ectopic, i.e. tubal pregnancy or. If the patient is having vaginal bleeding, ultrasound may be performed to confirm whether the fetus is still living. Otherwise, the first ultrasound is usually done at 18-21 weeks. ...Read more

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Could conception occur outside of the +/- 1 week margin of error based on the ultrasound?

Could conception occur outside of the +/- 1 week margin of error based on the ultrasound?

Yes if: 1) the pregnancy's abnormal and hence not the correct size, 2) the sonographer mismeasured or miscalculated. Otherwise, not really. ...Read more

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If ultrasounds have margin of error, how do u know when you're within the range of when the NT scan should be done? Does fetus have to be certain size?

Best estimate: The margin of error for ultrasound dating is the smallest in the first trimester, which is when the nuchal translucency scans are performed. Yes the fetus does have to be a certain size and between certain dates in order for the information to be accurate. ...Read more

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How accurate is a 7 week ultrasound? Any room for error?

How accurate is a 7 week ultrasound? Any room for error?

Need more info.: Accurate for what? Determining viability or age of gestation? Regardless no test is '100%'. ...Read more

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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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How come there's a error of a week even with a early ultrasound! When it comes to conception?

How come there's a error of a week even with a early ultrasound! When it comes to conception?

Simple.: Because not all people are made the same and no test is perfect. Generally it is not critical to have perfect dates. ...Read more

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How accurate is a 8 weeks ultrasound? Can it shows 8 weeks but actually to be in 16 weeks? Is if possible such a big error?

How accurate is a 8 weeks ultrasound? Can it shows 8 weeks but actually to be in 16 weeks? Is if possible such a big error?

Not an error: This has to do with the way the dates are calculated and the standard deviation in the method. An 8 week ultrasound has a standard deviation of only 1 week at most. Not 8 weeks. When there is such a large difference it is usually because the dates that were given were wrong. ...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 the margin of error in a 1st trim ultrasound based on error of measurements or assigning a due date? I hear diff things about how "off" they can be

Gestational age: It is reported as number of days that gestational age could be off, in days. Assuming that babies all mature similarly (a fairly good assumption within a week or two) this also applies to expected delivery date.

You have asked at least 3 questions about this topic. I suggest you read something more definitive such as this http://www. Nlm. Nih. Gov/medlineplus/pregnancy.Html. ...Read more

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Would the gestational age of 12wks+4days @62mm be off by 1 week since ultrasounds have a margin of error of 1 week in the first trimester?

Estimates: Determination of gestational age is based on estimates determined by the last menstrual period and ultrasound. There is a margin of error with ultrasound, but that does not mean that the gestational age is necessarily different by a week. It means that the ultrasound estimate is 12w4d with a very high likelihood that the actual age is between 11+ to 13+ weeks. ...Read more

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What is the error of margin for an ultrasound dating at 11 week 4 day, measuring the fetus crl at 4.8 cm?

Plus or minus, 5 day: The margin of error at that gestational age is typically + or minus 5 days. That crl is definitely normal for that gestational age. ...Read more

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Ultrasounds in the first 4 to 6 weeks of pregnancy can only have a error of 3 to 5 days?

Ultrasounds in the first 4 to 6 weeks of pregnancy can only have a error of 3 to 5 days?

very accurate: If done properly the first trimester ultrasound measuring the actual embryo length is the most accurate dating method. ...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 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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Accuracy of early ultra sound at 6 weeks. What is the acutal error margin. I did 2 us and both detect 6 weeks +- 3 days margin aadvised by dr?

Earlier = better: The earlier the ultrasound, the more accurate it is. Before 12 weeks the margin is days, after 30 weeks, the margin can be weeks. ...Read more

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Is it possible that at the sonogram the doctor to see a baby of 5 weeks but to be pregnant in 3 months? Is it possible such a big error?

Is it possible that at the sonogram the doctor to see a baby of 5 weeks but to be pregnant in 3 months? Is it possible such a big error?

No: Pregnancy dating by early (first trimester) ultrasound is very accurate. It would not be possible to mistake a viable 3 month pregnancy for a 5 week pregnancy. Dates may be off by days to a week or so, but not by months. ...Read more

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We thought I'm at 10w3 d, but ultrasound measures 5.03CRL and 11w6d. could this be correct?

We thought I'm at 10w3 d, but ultrasound measures 5.03CRL and 11w6d. could this be correct?

Yes: Early ultrasounds are very reliable for dating. The traditional method of dating from the first day of the last menstrual period is less so since ovulation may occur earlier or later and conception can occur a couple of days after ovulation. Hope this helps. ...Read more

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I was curious how far along i'd be if the ultrasound said 6.5 cm/1.3/27 Hz at the top of my picture.?

I was curious how far along i'd be if the ultrasound said 6.5 cm/1.3/27 Hz at the top of my picture.?

Sorry Mildred,: Those numbers are most likely related to the ultrasound settings, (Depth/gain/frequency) Ask your OB or sonographer for your dates or measurements. In early pregnancy we measure crown-rump-length (CRL). Later, the fetal head diameter (biparietal diameter or BPD) from "ear-to-ear." Also look for abd. Circumference (AC), head circum. (HC), or femur length (FL) since these are used more often. ...Read more

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How far off can dates be at an early ultrasound to be worried? I ovulated around day 16-17 but I calculated 6 wks a d 5 days. Scan showed 6wks

How far off can dates be at an early ultrasound to be worried? I ovulated around day 16-17 but I calculated 6 wks a d 5 days. Scan showed 6wks

Same thing: The ultrasound is only accurate within plus or minus two weeks. The ultrasound and your calculations are merely "estimates" of gestational age at this early point. ...Read more

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Are baby gender ultrasounds accurate? Is there any chance that an ultrasound showing my baby's gender is wrong? I'd hate to completely prepare for a b?

Depends on variables: I would never decorate my nursery based on a baby gender ultrasound. Those done around 20 weeks are likely to be accurate in the hands of a skilled technician, but the boy parts must decide to show themselves or they may be overlooked. I've heard of more moms being surprised by boys than girls. ...Read more