In some situations, such as when the scan is completed before 10 weeks of gestation or you are overweight, you may also need a vaginal scan. Your sonographer will let you know if this is needed.
For an abdominal dating ultrasound, you will need to have a full bladder. You may be asked to drink some water and not go to the toilet beforehand because a full bladder helps to push your womb up to give a better picture. For a vaginal scan, you can have an empty bladder. This will provide a fairly accurate estimate of how many weeks pregnant you are. But it is important to remember that only a few women go into labour on their due date, so it can be more helpful to think about the month in which you are expecting your baby, rather than the exact day.
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Information on pregnancy ultrasound scans including when they are taken, what it can be used for, dating scans, anomaly scans, plus links to trusted resources. This Dads Guide to Pregnancy article covers early pregnancy scans and screening, plus normal fetal development and early miscarriage for men, by men.
In the second trimester of pregnancy, you may be offered to have an morphology scan anomaly scan. Learn about what it looks for and when it is performed. A nuchal translucency scan is part of the ultrasound scan that may give an indication of chromosomal abnormality.
Ask a midwife: When should I get a dating scan?
Learn more about how and when it is performed. During your pregnancy, you will be offered a number of tests and scans. The aim is always to check on the health of you and your baby, but it can sometimes be overwhelming and confusing. Handy infographic that shows what you can expect at each antenatal appointment during your pregnancy. In the meantime, we will continue to update and add content to Pregnancy, Birth and Baby to meet your information needs.
This information is for your general information and use only and is not intended to be used as medical advice and should not be used to diagnose, treat, cure or prevent any medical condition, nor should it be used for therapeutic purposes.
How is a dating scan performed?
Babies measuring small at 20 weeks just says you have a small baby in there. Out of curiosity what was the birthweight of your DS?? I had the same thing happen with my DD. At the 20 weeks scan she measured 17 weeks and they made me go back in 2 weeks when she measured 19 weeks.
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They tried to push my dates back but like you I knew when my LMP was and cycle length and I had had a scan at 9 weeks which was right for my dates. DD was born at 39 weeks weighing in at a whopping 4lb 11 or g tongue. No scan for dating is always right.
Are late scans accurate for dating? in Your Pregnancy | Forum | Huggies
Mine have being cause i knew my last AF and how long it went for. If you are concerned ask you doctor and see if you can have another scan done at a later date. Nodrog New Zealand Total posts: It seems pretty unlikely that you would ovulate 3 weeks late! My midwife said any scans after 12 weeks aren't accurate as by then the genetic differences will have started to show eg I'm 5 ft 9 and DH is 6 ft 3 so our baby is likely to be bigger than someone who is 5 ft 2 with a partner of 5 ft 9 IYKWIM.
Why would I have a dating scan?
With my current pregnancy I knew my LMP date but didn't get a positive test until over a week after AF was due, it turned out that I ovulated a week late. But as I said earlier it is pretty unlikely that you would have ovulated 3 weeks late without noticing as that is a week after your AF should have shown up.
Two bouncy boys New Zealand Total posts: No as acurate but neither is going off the date of your LMP With it so far out they will probably go off the new date. Find out more about the combined screening test for Down's syndrome. You won't be offered the combined screening test if your dating scan happens after 14 weeks. Instead, you will be offered another blood test between 14 and 20 weeks of pregnancy to screen for the risk of Down's syndrome.
This test is not quite as accurate as the combined test. Skip to main content. Your pregnancy and baby guide.
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