Twin-Twin Transfusion Syndrome

Garrett Lam, MD, is medical director Banner Maternal-Fetal Center
at Banner Good Samaritan Medical Center.

Question: I have heard about twin-twin transfusion in the news. Can you tell me more about it?

Answer: Twin-twin transfusion occurs when the circulatory system of identical twins are connected in the womb. While often identical twins share a placenta, in twin-twin transfusion the connections shared in the placenta result in one baby donating a large part of its blood volume to the other twin. This happens in about 10 percent of identical twin pregnancies.

Some babies can go on to develop normally with no intervention depending on the severity of the condition. Because identical twins present a higher than normal risk of complication, however, ongoing monitoring such as regular ultrasounds is recommended.

In twin-twin transfusion, one or both babies can become threatened by an abnormal movement of blood, fluid and nutrition. One baby may become overwhelmed by the fluid levels and even suffer heart failure, while the other baby is starved for the nutrients that it is not receiving from the placenta.

Twin-twin transfusion has been seen as early as 14 weeks of pregnancy, but rarely appears after 28 weeks of pregnancy. The need for intervention becomes clear when the amniotic fluid sacks around the babies differ greatly in the amount of fluid. As the disease becomes more severe, we may see problems with the heart function of one or more twins as well blood flow through the placenta such that intervention in the womb is necessary.

Sadly, at times, rescuing the stronger of the two twins will be the best possible outcome for the pregnancy. In some cases, one baby does not develop in a way that would be compatible with life outside the womb. For example, a baby that does not have a functioning heart or brain.

If you are expecting twins that have been diagnosed with this condition, it is important that you are seen by a perinatologist with experience in twin-twin transfusion. The potential treatment options should be carefully explained to you and your family. Laser ablation, a procedure that will interrupt the abnormal blood flow between the two developing babies, is one consideration.

At the Banner Maternal-Fetal Center at Banner Good Samaritan we offer comprehensive maternal-fetal care – from expertise in multiple pregnancies and other high-risk conditions, to fetal therapy and ultrasound expertise, to specialized neonatal care for your babies.