12 week dating scan accuracy


22-May-2017 11:31

Charts have been developed for this purpose, but some simple rules of thumb can also be effectively used.From 6 to 11 weeks gestational age, the fetal CRL grows at a rate of about 1 mm per day.

12 week dating scan accuracy-57

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For example, a CRL of 23 mm would correspond to a gestational age of 9 weeks and two days (6 weeks plus 23 days = 9 weeks and 2 days).

First trimester ultrasonic scans may show 'soft' markers for chromosomal abnormalities, such as an increased fetal nuchal translucency (back of the neck) to enable detection of Down's syndrome fetuses.