Dating gestational age ultrasound, assessment of gestational age by ultrasound
Rationale for developing a new international growth reference. The scan or my dates - which should I believe? Only 4 percent of women deliver on their EDD, in part because of the limitations of methods used to estimate gestational age, but also because of natural biologic variation in the pace of fetal maturation and the timing of natural delivery [ 1 ].
J Obstet Gynaecol Res. The SDs in this equation are the predicted estimates from the regression analysis.
The measurement used for dating should be the mean of three discrete CRL measurements when possible and should be obtained in a true midsagittal plane, with the genital tubercle and fetal spine longitudinally in view and the maximum length from cranium to caudal rump measured as a straight line 8, Comparison between lateral and axial ultrasonic measurements of the fetal femur. Image-scoring system for crown-rump length measurements. The accuracy of gestational age estimation by HC measurement is comparable with that of BPD measurement.
Sometimes a trans-vaginal examination shows that your pregnancy is less advanced than expected. Acta Obstet Gynecol Scand The operator was instructed to avoid applying too much pressure with the transducer as this can distort the circular shape of the fetal abdomen. Goldenberg RL, Nelson K: The prediction of fetal maturity by ultrasonic measurement of the biparietal diameter. Traditionally, GA is estimated using the first day of the last menstrual period LMPwhich assumes that ovulation occurs on day 14 of the menstrual cycle.
Because this practice assumes a regular menstrual cycle of 28 days, with ovulation occurring on the 14th day after the beginning of the menstrual dating gestational age ultrasound, this practice does not account for inaccurate recall of the LMP, irregularities in cycle length, or variability in the timing of ovulation. Abdominal circumference Biparietal diameter Cephalic index Crown-rump length Estimated date of delivery Femur length Fetal biometry Gestational age assessment Gestational sac size Head circumference Intrauterine growth Normal pregnancy Prenatal ultrasonography Gestational age Prenatal testing Transvaginal ultrasonography Yolk sac.
To assist clinicians in assigning gestational age based on ultrasound biometry. With rare exception, if a first-trimester ultrasound examination was performed, especially one consistent with LMP dating, gestational age should not be adjusted based on a second-trimester ultrasound examination.
Assessment of fetal optic chiasm: