Doctor insights on:
Why Repeat First Trimester Ultrasound For Twins
Will a vanishing twin (lost at 7 weeks) affect first trimester downs syndrome testing with blood test and ultrasound?
Vanishing twin: No, it would not affect your test result. Ultrasound would show it for a while, but the developing twin will eventually grow big enough to hide it from view. ...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
Is there any way to determine twins in the first trimester other than an ultrasound its like I have a feeling that im haveing twins. I feel like im already starting to show at 6 weeks.?
No: Ultrasound is the only definitive method.Get a more detailed answer ›
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
Early Ultrasounds: Actually they are thought to be the most accurate. ...Read more
Diagnostics: This question is hard to answer because it depends upon what you're looking for with your first trimester ultrasound. If you're trying to figure out how far along you are in the pregnancy that is excellent, if you're trying to figure out if your baby has Down syndrome it's not perfect and will require further work up with other blood tests and ultrasounds. ...Read more
IT INCREASES: Your Progesterone levels are very high when you are pregnant. With twins even higher. Your corpus luteum (the remainder of the cyst that formed your egg, then released it) continuous to produce Progesterone until the placenta takes over. When you are having two babies the levels are usually higher. You can have some side effects from this (bloating, constipation, gassiness, breasttenderness). ...Read more
Off?: Depends what you mean by 'off.' the theoretical accuracy of a 1st trimester us is considered to be +/- 2-3 days, so in that sense they are always 'off.' if you mean wrong, as in more than 2-3 days, no one knows this - but with a skilled sonographer and a current us machine, it shouldn't be off by more than a few days very often. ...Read more
No: First trimester ultrasounds are the most accurate for estimating gestational age within +/- 7 days. ...Read more
Sometimes: The ultrasounds are accurate + or - 2 weeks. That is why we use other parameters to ferret out accurate conception and delivery dates. ...Read more
Unlikely: This early more likely accurateGet a more detailed answer ›
Can conception range be over a week off if gestational age is confirmed by early first trimester ultrasound?
Will a vanishing twin (lost at 7 weeks) affect the results of first trimester Down's syndrome blood testing?
Unlikely: These tests rely on the active production of various markers in the blood and so a demised twin this early on will be unlikely to affect the test. These tests however, should be interpreted in the setting of a screening ultrasound to help better understand the risk. That being said, no test is ever 100% accurate, though they are useful. Consultation with a genetic counselor will help. ...Read more
What changes a due date? And why is the first trimester ultrasound more accurate than the second trimester ultrasound?
Ultrasound dating.: First trimester ultrasound is by far the most accurate in determining the precise due date (+/- 3-7 days, depending on exactly when it is performed). Second trimester sonograms are less accurate but still helpful in pegging down the due date within +/-7-12 days. Third trimester scans are not very accurate in dating the pregnancy, as growth varies (+/- 14-21 days). Menstrual dating is not very good. ...Read more
Can first trimester dating ultrasounds be a month off gestational age? (if taken at 8 weeks) could I have been 13 weeks and they measured 8?
Unlikely: Ultrasound dating is very accurate when done around 8-11 weeks of gestation. But, as always, life is not perfect and mistakes can happen. A woman should be able remember what she was doing 6 weeks ago (around the time of conception) if the u/s scan is showing 8 weeks gestation. ...Read more
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
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
Possible: Usually not in the first weeks-4 to 6, but as the time of gestation progresses the estimation of gestational age can change. ...Read more
Early Ultrasound: Nope. These are thought to be the most accurate. ...Read more
How accurate are ultrasounds in the first trimester I'm due may 14 and the baby measuring 3.1 cm. So should I be futher along?
Very accurate: 1st trimester ultrasounds are the most accurate ultrasounds for dating a pregnancy. At 3.1cm today, your 10 weeks along and a due date of 5/14 is within accuracy. If you're not exactly 10 weeks today, then this information not helpful. You need date of ultrasound, gestational age on that date, and edc, as well as crl. ...Read more
It can show discord: A first trimester ultrasound is extremely accurate in determining how far along you are, and when the exact due date is. It is possible for it to show that the pregnancy is 2 weeks 'off' from what the expected due date was. As long as it was done by a qualified sono technician or physician, it's unlike for it to be 2 weeks inaccurate in the first trimester. You may have ovulated earlier (or late. ...Read more
Early Ultrasounds: The early ultrasounds are considered the most accurate. ...Read more
No: A late first trimester ultrasound (i.e., 12 weeks) may be off by as much as a week in either direction but unless done by a completely incompetent sonographer, 3 weeks would be unheard of. Earlier in the first trimester the accuracy is even better with a range of less than a week. ...Read more
Should be within: 4-6 days at the most and often times within 1 or 2 days. ...Read more
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