How Accurate Is Crl
The Rate of Growth of the Normal Gestation Sac Is 1.1 Mm/Day. Measurement of the Crown–Rump Length (Crl) Between 6 and 12 Weeks Is the Most Accurate Dating...
The rate of growth of the normal gestation sac is 1.1 mm/day. Measurement of the crown–rump length (CRL) between 6 and 12 weeks is the most accurate dating parameter. CRL measurements of gestational age are accurate to within 3–5 days.
Can CRL measurement be wrong?
Out of 806 of the CRL measurements, 323 (40.1%) were qualified as accurate, 279 (34.6%) as inaccurate, and 204 (25.3%) as inaccurate, but not changing the duration of a pregnancy. 527, i.e. 65.4% of the measurements of crown-rump length made it possible to ensure the accurate assessment of gestational age.
How accurate is CRL at 6 weeks?
At 6 weeks’ gestation there was an observed difference in CRL of 3.7 mm, equivalent to an underestimation of 4 days by Robinson. From 11 to 14 weeks’ gestation there was an observed difference in CRL of 0.9–1 mm, equivalent to 1 day overestimation by Robinson.