INTRAUTERINE DEMISE OF A FETUS

IN MULTIPLE PREGNANCIES

- VANISHING TWIN SYNDROME

- VANISHING TRIPLET SYNDROME

• This concept was based on the findings that the incidence of early twin gestations was significantly higher than that noted later in pregnancy (about 5% versus 1 in 90 deliveries).
• Can occur at any time during the gestation but is most common in the first trimester.
• True loss rate is approximately 20% (1).
• Loss prior to 15 weeks gestation may result in no sonographic evidence of a twin pregnancy at a later date (pathologic examination at delivery may show no evidence that the twin ever existed) (2). This has been termed the "vanishing twin phenomenon" (1,3).

Demise of one embryo in a dichorionic twin pregnancy
Demise of one embryo in a trichorionic pregnancy

• Loss of one twin in the second trimester may result in compression and mummification of that fetus. This has been called fetus papyraceus. The compressed fetus is a thin structure of residual bone and tissue stuck against the uterine wall.
• Loss of a twin in the late second and third trimester leads to fetal maceration.
• Risk to surviving twin.
• Minimal in dichorionic twins.
• In monochorionic twins, vascular injuries as a result of thrombotic emboli or disseminated intravascular coagulation pose a small additional risk to the surviving twin (4).

VANISHING TRIPLET SYNDROME

OUTCOME

Link to Outcome of Multiple Pregnancies

REFERENCES

1. Landy HJ, Weiner S, Corson SL et.al. Ultrasonographic assessment of fetal disappearance in the first trimester. Am J Obstet Gynecol 1986;155:14.
2. Levi S. Ultrasonic assessment of the high rate of human multiple pregnancy in the first trimester. J Clin Ultrasound 1976;4:3.
3. Janiaux E, Elkazen N, Leroy F et.al. Clinical and morphological aspects of the vanishing twin phenomenon. Obstet Gynecol 1988;72:577.
4. Johnson SF, Driscoll SG. Twin placentation and its complications. Semin Perinatol 1986;10:9.