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A member asked:
Why would u/s tech say i was 17 weeks & 4 days based on my lmp, but then afterward say i was 18 weeks once she started the ultrasound?
A doctor has provided 1 answer
Accuracy: Ultrasound gets less accurate as the fetus gets older. They were probably estimating from your lmp, but the structure the ultrasound first measured was around 18 weeks. This is still within range.
Answered 10/8/2013
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