What is Twin-Twin Transfusion Syndrome and how does one get it?
This condition occurs only in those identical twins that are monochorionic, diamniotic (one-third of all identical or monozygotic twins). In almost all of these pregnancies, the single placenta contains blood vessel connections between the twins. For reasons that are not clear, in 15 percent to 20 percent of monochorionic, diamniotic twins, the blood flow through these blood vessel connections becomes unbalanced, resulting in a condition known as twin-twin transfusion syndrome (TTTS). This is not an inherited or genetic condition. It is not caused by something that a mother or father has done or not done. In TTTS, the smaller twin (often called the donor twin) does not get enough blood while the larger twin (often called the recipient twin) becomes overloaded with too much blood. In an attempt to reduce its blood volume, the recipient twin will increase the urine it makes. This will eventually result in the twin having a very large bladder on ultrasound, as well as too much amniotic fl
