[Vaginal ultrasonography in the first trimester. II. Quantitative parameters].

To study the development of the size of various gestational parameters in the first trimester, the vaginal sonographic measurements in 259 normal intrauterine singleton pregnancies with reliable dates between 4 and 13 complete weeks menstrual age were analysed. Growth curves of the mean chorionic cavity diameter, the maximum thickness of the trophoblast, the yolk sac diameter, the crown-rump length, the mean amniotic cavity diameter, the biparietal diameter, the transverse abdominal diameter and the femur length as well as the course of the embryonic heart rate together with their 90% confidence limits, respectively, are shown. Normal values are given to estimate pregnancy age from the various parameters. The confidence interval of gestational age to the 95th and 5th percentile, respectively, was +/- 6 days using the crown-rump length, +/- 8 days using the biparietal or transverse abdominal diameter and +/- 9 days using the mean chorionic diameter.