Twin-to-Twin Transfusion Syndrome: Prognosis & Treatment

Instructor: Courtney Dohse
In this lesson, we will review the definition of twin-to-twin transfusion syndrome, learn about treatment options, and take a look at the prognosis or outlook of this syndrome.

Charlotte has just learned that she is pregnant with identical twin boys. Upon having her first ultrasound, she is told that the boys share a placenta. She is scheduled for a follow up ultrasound in a few weeks, which reveals that Twin B is growing much faster than Twin A. Twin-to-twin transfusion syndrome is suspected, so Charlotte is scheduled for weekly follow-up ultrasounds for the remainder of her pregnancy.

Overview of Twin-to-twin Transfusion Syndrome (TTTS)

Twin-to-twin transfusion syndrome occurs in 15% of women who are pregnant with identical twins. It occurs only in twin gestations where the fetuses share a placenta. For this reason, it cannot occur in fraternal twins. In twin-to-twin transfusion syndrome, blood vessels of the shared placenta are connected in both babies. This results in one twin shunting much of his blood to the other twin. This unequal sharing of blood can cause complications in both babies. In the above example, Twin A would be considered the donor twin, meaning he is the one pumping blood to the other twin. This is why he is smaller and not growing as rapidly. Complications for twin A might include, oligohydramnios or low amounts of amniotic fluid. He may also have a small or absent bladder.

In this scenario, Twin B is considered the recipient twin, because he is receiving not only his own blood supply from the placenta, but also the blood that the other twin is pumping to him. The complications of this are polyhydramnios, or an overabundance of amniotic fluid, as well as an enlarged bladder and even potentially heart failure. This is because his body is not able to keep up with the oversupply of blood.

twin-to-twin transfusion syndrome

After the diagnosis of twin-to-twin transfusion syndrome, Charlotte asks you about the prognosis of her babies.


In the past, the prognosis for babies with twin-to-twin transfusion syndrome was not positive. Often, both babies died. But with early diagnosis and treatment, as well as careful monitoring throughout pregnancy, in mild cases, the prognosis is very good for both babies. In severe cases, often, one of the twins will survive.

With this being said, these pregnancies are considered high risk and must be monitored carefully. Often, weekly ultrasounds are scheduled to check the measurements of both babies. Many mothers are also asked to come in twice a week for a non-stress test (NST), where external monitors will be placed on the mother's stomach to record and chart the heartbeat of both babies. This allows the physician to assess fetal wellbeing in both babies.

Treatment Options

At Charlotte's follow-up visit from her last ultrasound, she inquires about the options she has for treatment.

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