Twin-to-twin transfusion syndrome (TTTS) occurs when the blood supply of one twin moves to the other through the shared placenta. The twin that loses the blood is called the donor twin. The twin that receives the blood is called the recipient twin.
Both infants may have problems depending on how much blood is passed from one to the other. The donor twin may have too little blood, and the other may have too much blood.
Most of the time, the donor twin is smaller than the other twin at birth. The infant often has anemia, is dehydrated, and looks pale.
The recipient twin is born larger, with redness to the skin, too much blood, and a higher blood pressure. The twin that gets too much blood may develop cardiac failure because of the high blood volume. The infant may also need medicine to strengthen heart function.
The unequal size of identical twins is referred to as discordant twins.
Peter J. Chen, MD, FACOG, Associate Professor of OBGYN at Cooper Medical School at Rowan University, Camden, NJ. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.