One risk for twin pregnancies is Twin-to-Twin Transfusion Syndrome (TTTS). This is a condition in which identical twins share blood supply due to an anomaly with the blood vessel connections of the placenta. Because of the connection, the smaller twin acts as a donor for the larger recipient twin – who receives excess fluid resulting in an enlarged bladder and an increase in amniotic fluid. For the donor twin, the lower levels of fluid can reduce bladder size and decrease amniotic fluid. The condition can be fatal for both twins.
Twin-to-twin transfusion syndrome treatments vary and may include fetoscopic laser surgery. The Colorado Fetal Care Center’s Dr. Timothy Crombleholme has performed more than 1000 cases of TTTS, with high survival rates. At the CFCC, survival rates for one or both twins is 97% and is 85% for both twins if there is no growth restriction.
Under the direction of Dr. Crombleholme, the Colorado Fetal Care Center provides evaluation and treatment of pregnancies complicated by TTTS.
Treatment of twin-to-twin transfusion syndrome is one of the most challenging clinical problems concerning multiple gestations. Approximately 20 percent of all twin pregnancies are monochorionic, and the incidence of TTTS in monochorionic diamniotic gestations is approximately 5 to 15 percent. TTTS is a phenomenon almost exclusive to monochorionic pregnancies.
The natural history of severe TTTS is well established with mortality rates approaching 80 percent to 100 percent if left untreated, especially when it presents prior to 20 weeks gestation in which case it tends to be more severe and more rapidly progressive.