Serum beta-hCG levels, Transvaginal Ultrasonic Measurements of Gestational Sac and Crown-rump Length as a Method of Assessing Gestational Age

Jung, B J; Lee, S H; Hur, M

Abstract

The two most common methods of gestational age estimation using ultrasound in early pregnancy are mean gestational sac diameter and crown-rump length[CRL]. For many years the crown-rump length has been acclaimed as the most reliable method of estimating gestational age in utero[accuracy+/-3~7 days]. But ultrasonic methods are less accurate before seven or after 31 weeks` gestation. During the first 60 days of gestation, the uninhibited secretion of human chorionic gonadotropin has a doubling time of approximately two days, which leads to an exponential rise in maternal serum human chorionic gonadotropin concentrations with little individual variation. Therefore, the best prediction of gestational age is provided by a combination of ultrasonic measurement and serum concentration of human chorionic gonadotropin. This study was undertaken to examine the correlation between serum beta-hCG and gestational sac and CRL with transvaginal measurements during early pregnancy in determining gestational age. These datas of 48 singleton pregnancies which results from in vitro fertilization and embryo transfer[IVF-ET] at Chung-Ang university hospital were assessed in the first trimester by transvaginal ultrasonography. All women included in this study went on to delivery normal infants at 37 completed weeks of after weighting over 2.5kg. we obtained the results as follows. 1. The beta-hCG concentration was 52.8+/-27.9, 236.5+/-177.1, 5782.7+/-6464.3, 27538.9+/-22446.0, 73748.1+/-46820.8, 99274.9+/-40436.7, 106916.0+/-38132.1, 99118.9+/-29788.0, 89046.9+/-30072.7 and 122481.0+/- 45521.4 mIU/ml in each week from 3 week to 12 week, respectively. It was estimated that in early pregnany, the doubling time of the concentration of beta-hCG in plasma was 1.4 to 3.4 days. 2. The mean gestational sac diameter was 12.3+/-6.3, 18.1+/-8.1, 29.1+/-8.9, 40.0+/-9.6, 45.6+/-10.4, 52.2+/-9.8 and 52.0+/-11.4 mm in each week from 5 week to 11 week, respectively. Positive linear correlation was observed between gestational sac diameter and gestational age[weeks][r2=0.637, p=0.0001]. 3. The mean crown-rump length was 6.7+/-0.6, 9.1+/-3.3, 10.7+/-3.5, 17.3+/-5.3, 24.9+/-7.8, 34.7+/-7.8, 41.6+/-10.9 and 42.6+/-14.3 mm in each week from 5 week to 12 week, respectively. We also observed the relationship between CRL and gestational age[weeks] as second-order polynomial equation. CRL=0.393[GA]2-6.846 [r2=0.686][p=0.0001]. 4. The fetal heart beat was detected from 6 week of gestation and all embryos` heart beat wear demonstrated until 10 week of gestation. The fetal movement was demonstrated from 8 week to 11 week of gestation. In conclusion. this study establish the early fetal growth with serum beta-hCG, G-sac diameter, CRL in our hospital on the basis of gestational age[week] using high resolution transvaginal ultrasonography.