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This syndrome is a complication of monochorionic twin gestation.
Monozygotic twins (identical twins) share a single placenta which results in vascular anastomoses (connections).
Usually, blood flow through these placenta anastomoses is bidirectional.
However, in about 10-15% cases of monochorionic twin gestations, this intertwin exchange is unbalanced and results in twin-to-twin transfusion syndrome. In this case, one twin becomes a donor as the second is a recipient.
The diagnosis of twin-to-twin transfusion syndrome (TTTS) is suspected by ultrasonography in the presence of amniotic fluid volume discordance in a monochorionic, diamniotic gestation.
If the condition is severe and not monitored or treated, both twins are at risk of dying in utero or exposed to cardiac, neurologic or other complications.
Early in pregnancy (before 13-14 gestational weeks) TTTS is usually undiagnosed.
In mid-gestation, the treatment is based on fetoscopy laser occlusion of chorioangiopagous vessels (FLOC) which can halt the syndrome.
In the third trimester, worsening TTTS is treated by delivery. 1
Dr Nicolas Kioumji
Pediatric
