[Transvaginal sonography: the differential diagnostic significance of the secondary vitelline sac in early pregnancy].

In the study reported here, yolk sac size and vertex-breech length were determined by transvaginal sonography, in addition to other parameters relevant to early pregnancy. Vital pregnancy was found without abortion symptoms in 72 cases, and with these symptoms in 35 cases; in 29 cases a missed abortion was found. The secondary yolk sac, which was detectable and measurable in 95 of 107 vital early pregnancies, showed constant growth from the fifth (diameter 3.9 mm) to the twelfth completed gestational week p.m. (diameter 6.5 mm). From the tenth completed gestational week p.m. onward, the yolk sac was not always detectable. Of the yolks sacs in the group of missed abortions, seven were found to be too small and 15 rudimentary. The correlation coefficients determined between yolk sac size and gestational age on the one hand and vertex-breech length on the other indicate that there is a significant relationship between the development of the yolk sac and that of the embryo up to the tenth completed gestational week p.m. Where a normally developed secondary vitelline sac is sonographically detected up to the tenth gestational week, the prognosis may be regarded as good. However, any finding which deviates from the norm must be verified, and the prognosis must be considered poor even when a living embryo is detected.