[Transvaginal ultrasound biometry in early pregnancy--a growth model].
PURPOSE: Evaluation of a growth model for the biometric parameters of early pregnancy: Chorionic cavity, yolk sac, amniotic cavity, crown-rump length and biparietal diameter. METHOD: 618 clinically well-dated singleton pregnancies of the first trimester were measured in a prospective cross-sectional study with high-frequency transvaginal ultrasound between 28 and 94 days post menstruation. RESULTS: Normal curves (5th, 50th, 95th percentiles) for all parameters were established using our growth model. The growth curves of chorionic cavity amniotic cavity, and biparietal diameter showed a linear growth whereas the growth curve of the crown-rump-length represented an exponential curve. Linear growth of the yolk sac was found until 8 weeks of gestation and there was no growth alteration after this time. CONCLUSION: With our growth curves of the first trimester it is possible to monitor the embryonic development with several parameters.