Ultrasound assessment of gestational age is feasible in a majority of pregnancies and may be used to establish gestational age with greater accuracy than physical examination. A comparison of the reliability of the estimated date of confinement predicted by crown-rump length and biparietal diameter. The AC is measured at the level of the fetal liver, using the umbilical portion of the left portal vein as a landmark Fig. While some showed only very slight differences in the estimation of dates compared to IVF dates e. Predicting delivery date by ultrasound and last menstrual period in early gestation. The abdominal circumference may be calculated using these diameters or measured directly. The prediction of fetal maturity by ultrasonic measurement of the biparietal diameter.
It takes about 14 days from the first day of the last menstrual period for conception to take place and thus for the conceptus to form.
Accurate determination of gestational age can positively affect pregnancy outcomes. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. American Journal of Obstetrics and Gynecology. Of further concern is the fact that there appears to be significant disagreement between existing charts where some given CRL lengths, predicted gestational age can vary by many days depending on which chart is referenced. Discordancy of the biparietal diameter after 28 weeks' gestation. Accuracy of gestational age estimation by means of fetal crown—rump length measurement.