Twin to twin transfusion syndrome, or TTTS, is a serious condition that can occur in babies that share a placenta in the womb (identical twins or higher order multiples). TTTS occurs when the shared placenta contains abnormal blood vessels that connect the umbilical cords and circulation of the fetuses. The placenta may also be shared unequally (for example, one twin has access to ¾ of the placenta and the other only ¼) and one twin may not receive the necessary nutrients to grow normally.
When the blood vessels become abnormally connected, one baby (the recipient) may receive too much blood flow, while the other (the donor twin) does not receive enough. The donor twin may experience slower than normal growth, have poor urinary output and little to know amniotic fluid. Too much blood flow to the recipient can put strain on the heart, potentially causing heart failure. The recipient might have a more active bladder causing greater amounts of amniotic fluid.
TTTS can occur at any time during pregnancy, but is considered more serious between 12-26 weeks gestation because the babies are too young to be delivered safely. However, thanks to advances in science there are some treatments available to help twins with TTTS.
First of all, mothers of twins with a shared placenta should be monitored heavily by a Maternal Fetal Medicine (MFM) clinic. Ultrasounds should be performed biweekly to check on things such as amniotic fluid levels, blood flow in the placenta, visible bladders, size differences, etc. All of these can be indicators of TTTS.
If TTTS is detected, there are now treatment options (before, TTTS usually claimed the lives of both babies).
- Delivery of the babies – this will obviously need to be later in gestation, at a date when the babies are viable and their lungs have matured enough.
- Amniocentesis to drain excess amniotic fluid. This can improve the blood flow in the placenta and reduce the risk of preterm labor.
- Laser surgery to seal off the connection between the blood vessels. Laser surgery is often preferred to amniocentesis because it only needs to be done once. Amniocentesis may need to be done repeatedly to maintain proper blood flow. Laser surgery has an 80-65% survival rate of at least one twin, 65-70% overall twin survival, and 5% or less significant handicap rates in survivors.
Below is a video to help you better understand TTTS.