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How accurate are early ultrasounds in dating pregnancy

how accurate are early ultrasounds in dating pregnancy-21

This test gives us an indication of whether we should worry about your baby based on these results.This means that combined first trimester screening will not give us a definitive answer.

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For more information of prenatal diagnostic testing, please go to: The nuchal translucency is the fluid found at the back of your baby’s head and neck, just beneath the skin.A nuchal translucency ultrasound (commonly called a “nuchal scan” or “NT scan”) is an ultrasound performed between 11.5 and 13 weeks 6 days gestation.It is usually part of an assessment called combined first trimester screening.An increased NT measurement does not always mean the baby has a problem but it does increase the risk.There are established and strict criteria for the accurate measurement of the nuchal translucency.Nuchal translucency ultrasound alone can also provide this risk assessment, but it is not as accurate as combined first trimester screening.

Combined first trimester screening is a non-invasive way of assessing your risk, which means it does not involve putting needles into the placenta or amniotic sac, as happens with CVS and amniocentesis.

Combined first trimester screening assesses the risk for your baby having certain chromosomal abnormalities (trisomy 13, 18 and 21).

This testing combines the nuchal translucency ultrasound with specific blood tests.

Your sonographer will be experienced at performing these ultrasounds during pregnancy. It involves scanning with the ultrasound probe lying in the vagina.

The transvaginal ultrasound probe is thin, about 2cm diameter.

Occasionally, patients need to return on another day if the baby remains in an unhelpful position.