Doctor insights on:
Are Earlier Or Later Scans More Accurate In Predicting Due Dates
So would a transvaginal untrasound dating me at 7 weeks 3 days be early rather than late in guessing the date of conception?
Perfect time: Gestational age between 6 and 10 weeks is the most accurate way of determining date of conception. The error is about 3 days in either direction at that gestational age. ...Read more
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
If labor/delivery occurs after your due date, did conception occur later than suspected from the dating ultrasound?
Some variability: Us dating between 8-13 weeks is the most accurate to within +/- 3-4 days. It is possible the dating by last menses may be incorrect as well, especially if menses are variable. Although most women deliver around 40 weeks, not every delivery happens at 40 weeks. Some are a couple of weeks early, others late. Please discuss any questions with your doctor. ...Read more
How accurate are ultrasounds during early pregnancy? I had one at the ER are the ones given in the obgyn office more accurate? Thoughts? Transvaginal
Both are accurate: Er and ob/gyn are both accurate for gestational age; typically transvaginal is more accurate than transabdominal. Ultrasound performed in the er in early pregnancy are typically ordered to confirm whether or not you are pregnant, and how far along you are. The scans typically performed by your ob/gyn are often are more detailed to determine how your fetus and its anatomy are developing. ...Read more
Ultrasound dating: First trimester ultrasound is accurate within 5-7 days. 2nd trimester ultrasound has accuracy of +/_ 2 weeks. Lmp dating also assumes a 28 day cycle. There is no test that can date conception more accurately than a 1 week window. Due date is based on lmp unless us off by more than 1 week 1st trimester or 2 weeks in 2nd. ...Read moreSee 1 more doctor answer
Depends on dates: The ultrasound (us) is the most accurate way we have of deciding how pregnant you are. There is a variation in us accuracy due to how we measure and who is measuring, but the accuracy is about 3-4 days before or after the measured size until about 10 weeks, plus or minus a week to about 14-15 weeks, then gradually changing up to a 3 week range in the last 2 months of pregnancy. ...Read more
Very accurate: If done in the 1st trimester and done via transvaginal approach, it is accurate to 5-7 days ...Read more
Is is possible for the 'conception' date stamp on an ultrasound to be as much as 4-6 weeks later than the date of intercourse? Even in rare cases?
No, but...: Anything is possible in life, but the answer is "no". However, if a woman absolutely positively did not have sex except 4-6 weeks earlier than the date estimated by the ultrasound, then the scan's estimate is wrong. Likewise, if she did have sex around the date estimated by the scan, then believe the scan. ...Read more
Are 11 week ultrasound more accurate for dating conception than 6 week ultrasound, both are transvaginal?
Not necessarily: Due dating pregnancies is more accurate with more than one ultrasound performed. However, the 6 week ultrasound might be more accurate in dating your conception. Either way ultrasounds have a 'fudge factor' of 1 to 2 weeks in determining accuracy. ...Read more
When they do scans in first trimester by crl upto 13 weeks are these the most accurate measurements +/- 5 does this mean conception dates accuracy?
If you can still get pregnant within the 2 weeks of gestational age wouldnt that make the transvaginal u/s dating inaccurate as far as conception dating?
Depends...: Accuracy of conception date based on ultrasound depends on when the ultrasound is done. Ultrasounds done between 6-10 weeks of gestational age are especially accurate, to within a 6 day window. This is because in early pregnancy all babies grow at the same rate. Later in pregnancy, ultrasound have an error rate of a 4 week window. This is because genetic, nutritional & other factors impact growth. ...Read more
20 week anatomy scan gave due date 3 days earlier than dating scan done at 9 weeks. which due date should i go by? Are they both wrong?
The ultrasound: A second trimester US is much less reliable than a first trimester one. In this case, they are very consistent which makes your dating very reliable. Go with the 9 week ultrasound date. You did not mention your LMP, but if it is also consistent with the 9 week sono, that makes your dates even more reliable. ...Read more
Can longer implantation time affect dating ultrasounds in early pregnancy?Can it affect growth estimates in early pregnancy and date you behind?
"Dating" a fetus: The "dating" refers to the gestational age of the developing fetus not a social romantic encounter. Ultrasounds are only accurate plus or minus 2 weeks gestation unless done serially.(more than one). 'That is why OB MD's use multiple parameters to date pregnancies including LMP(last period), pelvic exam uterine size, etc. "Dating" is an inexact science in life and medicine. ...Read moreSee 1 more doctor answer
Embryo transfer: Embryo transfer would be the ultimate gold standard for gestation age.The number of days since conception of the transferred embryo (3-5 days) would be known so the precise time of conception would be available so the estimated due date could be more precisely estimated. ...Read more