Twin-to-Twin Transfusion Syndrome

Twin-to-twin transfusion syndrome (TTTS) is a rare condition which can affect pregnancies where there are multiple babies. The affected babies share the same placenta which is the point of contact between the umbilical cord and the uterus (womb). Through the placenta, oxygen and nutrients pass via the blood vessels from the pregnant woman to the unborn babies.

In TTTS there is an uneven sharing of the blood vessels between the unborn babies and this can develop to a point where one baby receives too little blood and so can struggle to grow and develop normally.  The other affected unborn baby receives too much blood and the baby’s heart will find this hard to pump around the body. The baby’s heart can begin to fail and this can also affect his or her growth and development.

The risks to the babies affected by TTTS depends upon whether they are the baby which receives too little blood (the donor twin) or too much blood (the recipient twin).  The donor twin will have less blood circulating over time and this means that the baby’s kidneys produce less urine. This results in low levels of amniotic fluid around the baby (oligohydramnios) or potentially no amniotic fluid (anhydramnios) and affects the development of the bladder. Amniotic fluid is essential to the development of a baby in the womb as swallowing the fluid and bringing the fluid into its lungs helps the baby develop its digestive tract, lungs and urinary system. Low blood volume can also affect the heart of the donor baby and this increases the risk of the baby dying before birth or suffering a brain injury.

The recipient baby has an increasing blood volume over time and this results in more urine production and more amniotic fluid than normal (polyhydramnios). The increased blood volume is difficult for the heart to pump around the body and, over time, the recipient baby may develop heart failure and may die before birth.

Pregnancies where there is more than one baby need to be monitored closely, to ensure that the babies are growing as expected and also to look for signs of possible TTTS. TTTS can occur where there is one placenta shared between the unborn babies and this should be picked up on ultrasound scans before 14 weeks of pregnancy. There are other signs which can be picked up on routine antenatal ultrasound scans and more detailed testing can be done using ultrasound by fetomaternal specialists. Key measurements include the volume of the amniotic fluid, how well the bladders of the babies fill and the blood flow measurements of the babies’ umbilical blood vessels.

Where the amniotic fluid increases in volume rapidly, this can cause the cervix to shorten and make the pregnant woman more likely to go into early labour or for the membranes to rupture. All pregnant women who are assessed for possible TTTS should therefore be check for the length of their cervix and whether there are signs of early labour or rupture of membranes.

The hearts of both babies should also be examined as this will indicate whether TTTS is affecting their ability to pump blood around their bodies.

A pregnancy affected by TTTS can be managed in different ways. Close monitoring may be enough for some pregnancies where the TTTS is not severe, and information from ultrasound scans can help the fetomaternal specialist grade the severity according to the Quintero grading system.

Where TTTS is considered more severe, treatments are available.  Amnioreduction is a process whereby the excess amniotic fluid is removed from the space around the recipient baby and can help reduce the risk of the mother going into early labour and help reduce the chances of either baby dying before birth. Fetoscopic laser is a surgical procedure which can stop the abnormal flow of blood between the affected babies. There are risks associated with this procedure and it can only be performed before around 26 weeks of pregnancy. However, it remains the only treatment which can cure TTTS.

TTTS, if not detected early and appropriately managed, can result in brain injury to one or more babies in a twin or multiple gestation pregnancy. If you had a pregnancy affected by TTTS and one or more of your babies suffered a brain injury and you have concerns over how your pregnancy was managed then please contact us – we would like to help. We have a team of experienced lawyers and medical specialists who can review the medical care you received and help answer your questions. We will provide you with the information and advice you need to make informed decisions about your child’s future and ensure your child’s rights are protected. Rest assured – the consultation is confidential and free of charge.