THE ORIGIN OF ALPHA-FETOPROTEIN IN FIRST-TRIMESTER ANEMBRYONIC PREGNANCIES

OBJECTIVE: Our purpose was to evaluate the origin of alpha-fetoprotein in the maternal circulation and coelomic fluid of pregnancies with an empty gestational sac on first-trimester ultrasonographic examination . STUDY DESIGN: The alpha-fetoprotein level and the affinity of alpha- fetoprotein for concanavalin A Sepharose was measured between 8 and 11 weeks of gestation in the maternal serum and coelomic fluid of nine p regnancies complicated by an empty gestational sac and of 27 normal pr egnancies. RESULTS: The maternal serum alpha-fetoprotein level in pati ents with an empty gestational sac was high in seven cases and normal in two cases. In these cases the median level was significantly (p < 0 .01) higher in the serum and lower in the coelomic fluid compared with normal pregnancies. In eight cases of the nine pregnancies with an em pty sac, > 50% of alpha-fetoprotein molecules in the coelomic fluid we re of the concanavalin A nonreactive fraction, whereas in one case the coelomic fluid sample contained <5% of this fraction. A similar distr ibution was found in the corresponding serum samples. CONCLUSION: Norm al or high maternal serum AFP levels and alpha-fetoprotein molecules p redominantly of yolk sac origin in the coelomic fluid of pregnancies w ith an empty gestational sac on ultrasonography provide further eviden ce that the most likely explanation for this feature is the early deat h of the embryo with persistence of the placental tissue.