ultrasound confusion

[cool_iies]

Re: ultrasound confusion

@ehl-e-chamman

determining EDD using ultrasound can vary according to when US was done.
most accurate EDD is via US in the first trimester when the fetus is small and CRL (crown to rump length) is used. This date is generally accurate to within 3 days of actual delivery date.
As your fetus grows … its no longer “straight” within your uterus … the curvature throws off the CRL measurement … sooo … In 2nd trimester BPD (biparietal diamter) size of babys head is used. This is accurate to within 10-14 days of actual delivery date.
IN the third trimester this accuracy decreases even more and its not uncommon for the date to be off by as much as 3 wks.

OP … go by the US date determined in 1st trimester.

my first trimester US gives my EDD 19 APRIL
this will be more accurate then