Twin to Twin Transfusion Syndrome (TTTS)

Definition - What does Twin to Twin Transfusion Syndrome (TTTS) mean?

Twin to twin transfusion syndrome (TTTS) is a condition that affects identical twins sharing a single placenta, also referred to as a monochorionic placenta. Blood from one fetal twin moves to another twin. The placenta may be shared unevenly by the two fetuses. This results in one twin having a minute share of the blood and nutrients (this baby is referred to as the donor twin) whereas the other baby receives more blood flow and nutrients (this twin is known as the recipient twin). TTTS affects 5-38% of monochorionic twins (i.e. twins sharing the same placenta) and only same-sex twins. It is a severe condition and can lead to miscarriage or result in a premature delivery to save the babies.

FertilitySmarts explains Twin to Twin Transfusion Syndrome (TTTS)

TTTS occurs when the blood vessels of the shared placenta are connected. The net flow of blood from the donor twin to the recipient twin occurs through the abnormal connections of the placental vessels. Since most of the necessary nutrients and oxygen are being transferred to the recipient twin, the donor twin falls short of the nutrients needed to grow normally or even stay alive. The donor twin also passes very little urine resulting in inadequate amniotic fluid levels or oligohydramnios (most of the amniotic fluid comes from baby’s urine).

The recipient twin's body, on the other hand, becomes overcrowded with blood and amniotic fluid. This extra blood exerts pressure on the larger twin’s heart to the extent that heart failure ensues.

If left untreated, miscarriage of the whole pregnancy is inevitable due to the lack of blood reaching the smaller twin and fluid and blood overload and heart failure in the larger twin.

TTTS is an emergency condition that is treated aggressively. The most common procedure to treat TTTS is reduction amniocentesis. In this procedure, the doctor drains the excess amniotic fluid from around the larger twin. This procedure may also help improve blood flow in the donor twin by establishing normal amniotic fluid volume in the recipient twin.

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