Vanishing Twin Syndrome

In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan.


Vanishing twin syndrome, as the name depicts, is a condition in which one of a set of twins or multiple embryos dies in utero, disappear, or gets resorbed partially or entirely, with an outcome of a spontaneous reduction of a multi-fetus pregnancy to a singleton pregnancy, portraying the image of a vanishing twin. In simple words, the number of embryos conceived, as observed via ultrasonographic examination in early pregnancy, differs from the number of fetuses delivered. This phenomenon occurs in multi-fetus pregnancies, commonly during the first trimester.

Twin loss can happen in the form of miscarriage, of which the mother is aware or in the form of vaginal bleeding or spotting in the first trimester without any knowledge of the mother, as vaginal bleeding is instead a frequent obstetric complication during the first trimester of pregnancy so that the twin loss may go unnoticed. This phenomenon can range from the disappearance of an early empty gestational sac to a sac that had developed a fetal pole to a fetus with documented heart activity.

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