A twin pregnancy brings with it extra risks no matter the type of twins they are. Twins that share a placenta bring with them a significant extra risk. The day we got the news of expecting twins, we weren’t given much information. See, our initial plans were to have our baby at a midwifery center, so our prenatal checkups were scheduled with a midwife. Immediately following the ultrasound, we met with one of the four nurse midwives to discuss the results. She happened to be very new to the facility, and wasn’t familiar with their practices, so there wasn’t a lot to discuss. With our appointment being after five o’clock in the afternoon, the only thing we knew at that time was that they were the same sex (although we didn’t know what), and there wasn’t anyone around to ask more questions.
Early the morning after our ultrasound, Callie received a call from the midwifery center to let her know that we needed to have another ultrasound, this one a high resolution with a perinatologist, or maternal-fetal medicine practitioner. It was at this point that we were told our babies were identical twins and shared a placenta. What the standard ultrasound couldn’t determine was whether or not the babies shared an amniotic sac. The ultrasound was scheduled two days later, and this is when we found out about the risks of a mono-di pregnancy, one of which is twin to twin transfusion.
Twin to twin transfusion is a dangerous, and potentially life threatening (to the babies) condition. It is brought on by what is typically referred to as a shunt (shortened pathway) developing between the two umbilical cords in the placenta. This shunt can allow blood to flow equally in either direction or more in one direction than the other. The situation becomes problematic when the blood flow is only in one direction. When this happens, one baby receives all of their oxygen and nourishment as well as a portion of the other baby’s fetal blood. This situation is equally dangerous for both the little ones, just in different ways. For the baby giving up some of the fetal blood, the obvious concerns are lack of oxygenation, undernourishment, and underdevelopment. In the case of the receiver, there can be enlargement of the heart and potential heart failure if the situation gets too bad.
The condition is typically diagnosed via ultrasound measurements of the babies’ sizes, as well as the relative measurements of the amniotic sac size. If you are pregnant with twins sharing a placenta, ultrasounds will occur on a regular basis, with increasing frequency the later in pregnancy you are. As long as the babies continue to grow at the same rate, and their isn’t a large discrepancy in the size of the amniotic sac, these will be rather uneventful, and even somewhat enjoyable from the standpoint that you get to “see” your baby more often. In the case that either of the two aforementioned signs begin to show, your perinatologist may want to see you more frequently, but that may only happen if the discrepancy shows a marked jump between appointments.
There are interventions your doctor may recommend that are possible to slow or stop the TTS, but this often depends on the gestational age of your babies. One intervention is to perform an amniocentesis to remove some of the fluid from the receiver baby. This takes pressure off of the heart, and equalizes the relative pressures between the amniotic sac for a period of time. There are pregnancies where an amniocentesis will be performed multiple times if the TTS begins early enough. Another, much more intrusive, remedy is to perform inutero laser surgery to close off the shunt.
Our pregnancy began to show signs of TTS at about 28 week’s gestational age, with a noted difference in both fetal size as well as that of the amniotic sac. This situation continued for about a month until a little past 32 ½ weeks. At that particular appointment, we had met the “threshold” or the situation where it starts to become more dangerous for the babies to be in the womb than outside of it. This threshold is typically when the babies are at or greater than 10% different in size. In our case, they were slightly over the 10%, and baby A had very little amniotic fluid while baby B had a very large, very full amniotic sac. At this point, we were told that these babies would be Continue reading →
