Top
30
Doctor insights on: Why Repeat First Trimester Ultrasound For Twins

Share
1

1
Will a vanishing twin (lost at 7 weeks) affect first trimester downs syndrome testing with blood test and ultrasound?

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

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


3

3
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??

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

6

6
Are first trimester ultrasounds ever exact in dating?

Are first trimester ultrasounds ever exact in dating?

Early Ultrasounds: Actually they are thought to be the most accurate. ...Read more

7

7
More back pain in first trimester mean twins?

More back pain in first trimester mean twins?

Probably not: Your obstetrician should be able to determine if you are having twins but back pain is not a good determinant. ...Read more

8

8
How accurate are first trimester ultrasounds done abdominal?

How accurate are first trimester ultrasounds done abdominal?

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

9

9
Do progesterone fluctuates with twins in the first trimester?

Do progesterone fluctuates with twins in the first trimester?

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

10

10
How is conception date calculated by first trimester ultrasound?

How is conception date calculated by first trimester ultrasound?

Measurements: US uses measurements of the gestational sac and then the growing fetus to date a pregnancy. The appearance of the heart beat. Usually measurements are compared to standards for various parts of the pregnancy and a date assigned. ...Read more

11

11
How often are first trimester ultrasounds off in dating conception?

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

12

12
Can a first trimester ultrasound gestational age/edd be wrong by 7 weeks?

Can a first trimester ultrasound gestational age/edd be wrong by 7 weeks?

No: First trimester ultrasounds are the most accurate for estimating gestational age within +/- 7 days. ...Read more

13

13
Can a conception date from early ultrasound be off 3 weeks in first trimester.

Can a conception date from early ultrasound be off 3 weeks in first trimester.

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

16

16
Can conception range be over a week off if gestational age is confirmed by early first trimester ultrasound?

Can conception range be over a week off if gestational age is confirmed by early first trimester ultrasound?

Yes: In general, ultrasound established dates should take precedence over menstrual dates if the discrepancy is greater than 7 days if done in the first trimester (first 12 weeks) and more than 10 days if done in the second trimester. ...Read more

17

17
Will a vanishing twin (lost at 7 weeks) affect the results of first trimester Down's syndrome blood testing?

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

18

18
What changes a due date? And why is the first trimester ultrasound more accurate than the second trimester ultrasound?

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

19

19
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?

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

21

21
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

22

22
Can first trimester ultrasounds be over 7 days off?

Can first trimester ultrasounds be over 7 days off?

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

24

24
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

25

25
Can a first trimester ultrasound be 19 days off?

Can a first trimester ultrasound be 19 days off?

Not likely: Measurements during the first trimester are usually accurate to +/- 7 days, and are established from the first day of bleeding from your last menstrual cycle. As the pregnancy progresses the dating becomes less accurate. ...Read more

26

26
Can a first trimester ultrasound be two weeks off?

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

27

27
How accurate are ultrasound in the first trimester?

Early Ultrasounds: The early ultrasounds are considered the most accurate. ...Read more

28

28
Can a first trimester ultrasound be three weeks off?

Can a first trimester ultrasound be three weeks off?

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

30

30
Are first trimester ultrasounds better at estimating conception or lmp?

Are first trimester ultrasounds better at estimating conception or lmp?

Better than later: A pregnancy dating ultrasound done at 8 to 11 weeks of pregnancy is pretty accurate when done by an experienced technician. The estimate can be a few days or a week off in either direction. ...Read more