The “Vanishing Twin”: Ultrasonographic Assessment of Fetal Disappearance in the First Trimester

Landy, M.D., H., Weiner, M.D., S., Corson, M.D., S.

Review of the sonographic findings of 1000 pregnancies with viable gestations in the first trimester revealed a minimum incidence of twinning of 3.29%. Of these, 21.9% demonstrated the “vanishing twin” phenomenon, often with associated bleeding, but with a good prognosis for the remaining fetus. Ovulation induction did not appear to alter these data. The sonographic criteria for “vanishing twin” are discussed. The incidence of multiple gestation is 3.29% to 5.39%, higher than previously believed. (Am J Obset Gynecol 1986;155:14-9.)