Twin-to-Twin Transfusion Syndrome
MEDICAL ANIMATION TRANSCRIPT: If you're pregnant with twins who have twin-to-twin transfusion syndrome, blood is passing from one twin to the other. Inside your uterus, your fetus receives blood through blood vessels in the umbilical cord connected to his or her belly button. The other end of the umbilical cord is attached to the placenta, a temporary organ inside your uterus. The outer layer of the placenta called the chorion contains many blood vessels that carry blood to and from the umbilical cord. The fetus floats in a watery substance called amniotic fluid. Surrounding both the fetus and amniotic fluid is a thin membrane called the amniotic sac. If you're pregnant with twins, they may share amniotic fluid, because they're both in the same sac, or each twin might have his or her own amniotic sac. These twins may each have their own placenta, or they might share a single placenta. Sometimes when twins share a placenta, blood passes between them through the placentas blood vessels. This rare condition is called Twin-to-Twin Transfusion Syndrome or TTS. In twin-to-twin transfusion syndrome, one twin called the recipient twin receives too much blood, while the other twin, called the donor twin, receives two little. When this happens, the excess fluid in the recipient twin's blood is filtered out of his or her body as urine. The urine passes into the amniotic sac, which makes the sac larger. Twin-to-twin transfusion syndrome happens in only a small fraction of identical twins that share a single placenta. It is also rare complication with triplets or any other multiple pregnancy the cause is not known. Complications that may result from twin-to-twin syndrome are pre-term birth. A condition called high drops, which is swelling of one or both of the twins or death of one or both of the twins. In addition, one or both twins may develop cerebral palsy or other brain impairments after birth. Treatment options for twin-to-twin transfusion syndrome include reduction amniocentesis, selective laser ablation, or selective cord coagulation. If you have reduction amniocentesis, a needle will be used to drain fluid from around the twin with excess amniotic fluid. This procedure may need to be repeated. During selective laser ablation, the blood vessels that allow blood to pass between the twins will be sealed off with a laser. If you have selective cord coagulation, one of the umbilical cords will be closed off with electrical current or a laser. This is performed when laser ablation is not possible or when one of the twins is not expected to survive. If you have a concern about twin-to-twin transfusion syndrome and your pregnancy, seek care at an experienced tertiary center. Your obstetrician may be able to provide you with a referral.