All AboutVanishing Twin Syndrome

Vanishing Twin Syndrome

Vanishing twin syndrome (VTS) is a miscarriage that happens in pregnancies with twins. It is a condition that occurs during pregnancy when one of the twins or multiple foetuses dies in the womb and is absorbed by the mother’s body, leaving only one surviving foetus. The ultrasound stops detecting the second foetus, and it seems as if it has vanished. This typically happens early in the pregnancy, often before the mother is even aware she is pregnant with multiples. Take a look at the article to learn about this syndrome in detail.

What Happens When One Twin Absorbs Another?

During pregnancy, one twin can be absorbed by the other, the placenta, or the mother. It can happen in the form of miscarriage or vaginal bleeding/spotting without the mother's knowledge. The phenomenon can range from the disappearance of an early gestational sac to a foetus with documented heart activity.

The vanishing twin may have the following physiologic outcomes:

• Resorption

Although resorption is considered the most likely physiological explanation for the disappearance of a certain proportion of the gestational sac, the actual incidence of resorption is still unknown. Studies have shown that resorption can occur anywhere from the seventh to the twelfth week of gestation. It is evident, however, that the resorption of a gestational sac during pregnancy does not affect the co-twin. Moreover, despite the loss of one twin due to resorption, the chances of survival for the other remain high, as this phenomenon mostly occurs in the first trimester.

• Blighted Ovum

A blighted ovum is a condition where an ultrasound scan shows a gestational sac without an embryo. Studies suggest that most pregnancies that end in the disappearance of the foetus are a combination of a normal pregnancy and an anembryonic pregnancy. If you experience vaginal bleeding in the first trimester, this may indicate the expulsion of the anembryonic sac. It is important to have a thorough ultrasound examination before considering dilation and curettage, as this procedure may accidentally lead to the termination of the surviving twin.

• Foetus papyraceous

Foetus papyraceous is a rare condition where a foetus becomes mummified, compressed, or flattened due to being positioned between the membranes of a viable foetus and the uterine wall. This typically occurs in pregnancies where the mother carries twins or more babies. The deceased twin usually passes away in the early second trimester. While in some cases, complete resorption may occur, in others, the twin may become macerated, which can potentially affect the other viable twin as the pregnancy progresses. Regular ultrasonographic examinations can help monitor this process. Additionally, a vanishing twin has been linked to some foetal malformations in the surviving twin, although the mechanism behind this is not yet known.