Clinical and Morphologic Aspects of the Vanishing Twin Phenomenon

Jauniaux, M.D., E., Elkazen, M.D., N., Leroy, M.D., PhD., F., Wilkin, M.D., PhD., P., Rodesch, M.D., PhD, F., Hustin, M.D., PhD., J.
The pathologic findings in placentas from ten multiple gestation complicated by the so-called vanishing twin phenomenon were studied to confirm the ultrasonographic evidence. Five pregnancies resulted from in vitro fertilization and embryo transfer, and five conceptions were spontaneous. The pregnancies were studied by repeat ultrasound examinations between five and 12 weeks’ gestation. First-trimester bleeding was the only clinical sign of this phenomenon was found in five cases. Morphologically, the lesions were characterized by well-delineated plaques of perivillous fibrin deposition, associated in one case with embryonic remnants. This focal degenerative change of the placental mass, which also exists in about 25% of placentas from uncomplicated term pregnancies, may be the only clue to the disappearance of one conceptus. (Obstet Gynecol 72:577, 1988) October,1988

The vanishing twin phenomenon has spurred the curiosity of many investigators since the advent of ultrasound in the last decade. There is no doubt that some twins or fetuses of higher multiple pregnancies die in utero before delivery. Ultrasound studies have demonstrated that the vanishing phenomenon occurs during the second half of the first trimester or early in the second trimester. However, morphologic evidence of tissue remaining from the disappearing twin has rarely been reported.

The chance of carrying a multiple pregnancy to term, when complicated by early embryonic disappearance, is good, and that the prognosis for the surviving twin is better in early cases than in cases of second- and third-trimester fetal death.