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Twin-to-twin transfusion syndrome

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A complication that is characterized by a disproportionate blood supply due to identical twins and higher order multiples sharing a single placenta


Twin-to-twin transfusion syndrome is a serious disorder when twins or multiples share a placenta in utero. It occurs when there is a disproportionate blood supply to the developing twins or multiples. There is a high risk of morbidity and mortality. A severe type of this disorder has a mortality rate of 60-100%.1 It is one of the serious complications that may arise from monochorionic twins or monochorionic multiples. In this form of twinning, the fetuses share a chorion and therefore a single placenta. A single placenta implicates a connected blood supply (anastomoses) to the monochorionic twins and therefore a shared blood circulation. There is a chance that blood transferred from one fetus (referred to as the donor) to the other (i.e. the recipient) is disproportionate. This results in the donor twin to have less blood volume and thus negatively affects the development and growth of the donor twin. It was also observed that the donor twin has decreased urinary output and oligohydramnios (i.e. a deficiency of amniotic fluid). When this occurs the recipient twin fetus's heart may be strained due to the increased blood volume. Apparently, this may lead to heart failure. There is also a heightened risk that the recipient twin fetus would have an increased urinary output and polyhydramnios (i.e. an excess of amniotic fluid).

Abbreviation / Acronym: TTTS

Also called:

  • Feto-Fetal Transfusion Syndrome (FFTS)
  • Twin Oligohydramnios-Polyhydramnios Sequence (TOPS)

See also:

1 Zach T, Ford SP. "Twin-to-Twin Transfusion Syndrome". EMedicine. Retrieved from [[1]].