How accurate are dating scans? |

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dating scan accuracy 12 weeks

Currently the most accurate non invasive test for detecting Down syndrome during pregnancy is the measurement of the nuchal translucency with an ultrasound between 11 to 14 weeks of pregnancy. I slept with someone on the 21st December and have spoken to my doctor about this and she says sperm can only live up to 3 till 5 days so the time frame misses it as I would of fell pregnant beginning of Jan. Implementation of maternal blood cell-free DNA testing in early screening for aneuploidies.

How accurate are dating scans?

How accurate are 12 week dating scans? I've just been for my 12 week scan and they have told me I am 15 weeks pregnant. Antenatal care for uncomplicated pregnancies. If they are less favourable they will increase the chance. Are you sure you want to delete this answer? Your toddler's sleep patterns Why won't your toddler settle down at night? Ultrasound ; 17 3:

Are you sure you want to delete this answer? That one is iffy. The general rule is: It's up in the air. Remember, this is plus or minus, which means an 8 day window vs 14 days. Additionally, your LMP last menstrual period should be taken into consideration. If you have regular cycles and are sure of the date of the first day of your last period, dating by menstruation is usually very accurate.

The doctors I work for would always use the earliest information to assign a due date, and would not keep changing it with each ultrasound examination. Not all doctors do this, however, I should add that I work for a major women's hospital which has been ranked in the top ten in the country. Ask you doctor which ultrasound she is basing your dating on. If it is the latter one, ask why. Maybe there is a good reason. Get an MBA while working. Related Questions In the uk week dating scan, how accurate?

How accurate are dating scans at 12 weeks pregnant? How accurate are 12 week dating scans? Perhaps you ovulated twice that month? I was sent to EPU as was being very sick. By my dates I was 7 weeks, by theirs I was 6 weeks. The sonographers explained that the earlier the scan the more accurate as the embryo has very standard development.

I had one embryo with fetal pole and heartbeat and one blighted ovum. The sonographer explained that indicated that this was a twin pregnancy with only one twin viable and could explain the date confusion as I may have ovulated twice in one cycle. I already have twins HTH ps Congratulations! Being pregnant can give a positive result on an ovulation test because the hormones are similar chemically as I understand it.

So is there any chance you could have been pregnant when you tested for ovulation? So it sounds like the scans are pretty accurate then. I did tell the Dr about the positive ovulation test and he didn't tell me that it could have been the pregnancy hormones, but that sounds like the most likely explanation.

I'm still not entirely sure what can have happened with the dates, and I definitely had a period thank god I didn't know I was pregnant or I would have thought I was having a MC , but I suppose I have got an extra 3 weeks of pregnancy 'for free' now!

I then went for another scan on the 22nd Feb and got told I was 9 weeks 1 day. I slept with someone on the 21st December and have spoken to my doctor about this and she says sperm can only live up to 3 till 5 days so the time frame misses it as I would of fell pregnant beginning of Jan.

If you know exactly how many weeks you are then count back. Do a conception calculator and out your due date in and then you will know. I went for what I thought was my 12 week scan No idea how it all works to be honest.

While they are probably generally accurate, is suspect there is room for error in measuring, the sonographer is only human! BHillary it would be the other way round. I would expect a 13 week fetus to be significantly bigger than an 11 week one. Going by my scan with DD1, I concieved on the first day of my period. DD2 was 3 weeks after, and DS was 3 days. This is all while using ovulation tests. PCOS here so anything is possible Scan dates are generally thought to be more accurate than going by period dates.

Yeah in inderstand that what I meant was if the lady thought she was 11 weeks from conception then went for a scan and was 2 weeks ahead than she thought it would be because he scan would have gone from lmp as he first 2 weeks of pregnancy you aren't actually pregnant.

For example of a clear blue didgital says from conception weeks you're actually weeks pregnant. Does that make sense? Registering is free, easy, and means you can join in the discussion, get discounts, win prizes and lots more. Already registered with Mumsnet? Log in to leave your comment or alternatively, sign in with Facebook or Google.

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How accurate are dating scans? I got told it was usually correct to within a week either way.

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dating scan accuracy 12 weeks

In the past few years it has been seen that approximately 3 in 4 babies with Down's syndrome do not have a visible nasal bone at the time of the first trimester screening test. Privacy Policy Terms of Use. What is actually done?

dating scan accuracy 12 weeks

Yes I am measuring it correctly - I was a bit obsessed and recorded everything in my diary. Occasionally the view is not clear and it may be necessary to perform a vaginal scan.

dating scan accuracy 12 weeks

I already have twins HTH ps Congratulations! Doesn't really make any difference as my daughter was 3 weeks early. If the two hormone levels are accuracj they will reduce the chance of your baby having Down's syndrome. I then went for another scan on the 22nd Feb and got told I was 9 weeks dating scan accuracy 12 weeks day. Pregnancy — screening tests. Register now Already registered with Mumsnet?