Vanishing Twin Syndrome Differential Diagnoses

Updated: Apr 12, 2021
  • Author: Ann L Anderson-Berry, MD, PhD; Chief Editor: Christine Isaacs, MD  more...
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Diagnostic Considerations

Important considerations

Do not perform dilation and curettage until it is certain that no viable fetus remains.

If chorionic villus sampling is performed during a multifetal gestation, be aware that a mosaic placenta may be present. A viable fetus with normal chromosomes may be supported by the placenta of a vanished twin with abnormal chromosomes. [27]

The full implications of fertility treatments that involve implantation of multiple eggs with reabsorption of several during the course of the pregnancy are unknown. [28]

Special concerns

Parents who have experienced a loss from vanishing twin syndrome often must deal with the death of one child while caring for another who is preterm or may have serious medical complications. Little is written on the long-term effects on the family. [29] One study examined parental attitudes on the psychological vulnerability of remaining singleton children after vanishing of a cotwin. This study found that, while parents perceived that these children had more motor difficulties, they thought of them as less vulnerable than controls. [30]

Other problems to be considered

The following should also be considered in cases of suspected vanishing twin syndrome:

  • Decidual reaction on sonogram

  • Amniotic cavity observed on sonogram as a second fetus

  • Chorionic sac observed on sonogram as a second fetus

  • Yolk sac or extraembryonic coelom observed on sonogram as a second fetus

  • Subchorionic hemorrhage or hydropic change in chorionic villi observed on sonogram as a second fetus [6]