TTTS occurs in about 15% of identical twins. It is diagnosed by a high risk obstetrician using ultrasound. This is a complication affecting a small number of identical twins in which the twins are sharing one placenta unevenly with each twin in it’s own sac of amniotic fluid. There are blood vessels in the placenta going from one baby to the other, so they are sharing the blood flow. Sometimes this sharing of blood is not equal. One baby gets less blood and one gets more, causing problems for both of them. There is no known reason why this happens in some pregnancies. It is not associated with other congenital defects or anything the mother might have done or not done.
There are many levels of seriousness of this disease from mild to moderate to severe. Some doctors think it is worse to find the disease early. Weekly ultrasound measurements of growth, fluid levels, the function of the fetal hearts and blood flow through the umbilical cords are used to determine how severe the problem is and decide if treatment is needed.
Treatment
Studies have not determined which treatment is best for TTTS. When choosing treatment options at Ohio State, the unique characteristics of each pregnancy are considered. A step-by-step approach is generally taken in order to minimize risks. One of more of these treatments may be performed.
- Amnioreduction removes excess amniotic fluid with a thin needle. This procedure has the lowest risk.
- Laser photocoagulation of the placental vessels uses laser energy to interrupt connecting blood vessels on the surface of the placenta, allowing each fetus to have their individual blood supply. This out patient surgery is only performed at certain fetal centers in the US, such as Ohio State University. This procedure has the most risk, but some studies show it is more effective in treating the cause of the disease.
- Septostomy uses a needle to make very small holes in the membrane separating the twins, so the amniotic fluid will equalize. This is the least common treatment, but it has been found to decrease the total number of treatments needed during the pregnancy.
- Bedrest may be suggested as a treatment also, but has not been proven to be beneficial. Often, some decreased level of activity is recommended because of the extra fluid and to prevent early labor. As these twin pregnancies progress, most mothers find that they cannot keep up their usual pre-pregnant activity level anyway. The level of activity recommended may change as the pregnancy changes.
In fact, most every part of a twin twin pregnancy is subject to change at any time. This disease can change quickly and without warning. Doctors have some ways to measure how the babies are doing, but often the outcomes and timing of upcoming events are unpredictable. In addition to the care for twin twin transfusion, regular visits to a local obstetrician are needed for the rest of routine care.
The goal of treating these pregnancies is to get the babies to an age where they can live outside their mother and be cared for in a neonatal intensive care unit (NICU). In the best situation, where the treatments have been effective or the disease is less severe, these pregnancies are delivered early. The place of delivery should be chosen based on the newborn intensive care services (NICU) available. For very premature infants, the NICU should have the designation of Level III, meaning they can provide any newborn service possibly needed.