About Twin-to-Twin Transfusion Syndrome (TTTS)

Twin-to-twin transfusion syndrome (TTTS) is a serious complication of twin and triplet pregnancies that occurs in 10 percent to 15 percent of twin pregnancies where the babies share the same placenta.

Normally, while the placenta is shared, the blood supply for each baby is separate. With TTTS, blood from one baby can mix with the blood of the other baby through small connecting blood vessels in the placenta. If blood is not shared equally between the babies, over time one of them (the "recipient twin") begins to suffer from complications of too much circulating blood, while the other (the "donor twin") begins to suffer problems from not having enough. TTTS can be mild or severe, depending upon how badly the babies are affected.

The recipient twin can develop complications such as heart failure (cardiomyopathy) and swelling (edema or fetal hydrops) and excess amniotic fluid (polyhydramnios). The donor twin can develop complications such as poor growth (intrauterine growth restriction), a lack of amniotic fluid (oligohydramnios) and other problems related to severe and prolonged blood loss (anemia).

In severe cases, if TTTS is not treated, there is a 60 percent or higher chance that both babies can die in utero. Babies who survive the pregnancy have a 25 percent risk of brain damage because of a lack of oxygen, blood and other nutrients. The pregnancy may also be lost because the uterus becomes over-distended from extra amniotic fluid. This condition may lead to premature labor or miscarriage. In less severe cases of TTTS, the outcomes improve; however the majority of pregnancies are still very complicated and usually end prematurely.


TTTS is usually diagnosed by ultrasound between 14 and 22 weeks of pregnancy. In severe cases, one baby is bigger and is overloaded with too much blood and fluid (this is the “recipient twin”). The baby also has a large amount of amniotic fluid around it. The other baby is smaller, has decreased blood volume and has only a small amount of amniotic fluid (this is the “donor” twin). TTTS can be mild or severe, depending upon how badly the babies are affected.


There are three treatment options for TTTS. The choice depends on the severity of the condition and your wishes as parents. These choices are:

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