Twin to Twin Transfusion Syndrome

Twin to Twin Transfusion Syndrome

Twin to twin transfusion syndrome or TTTS is very rare and occurs only in identical (mono-zygotic) twins. This happens when blood is transferred from on baby to the other through blood vessels within a shared placenta, monochorionic. It can be dangerous for both babies, the donor twin, who loses blood and doesn’t have enough, and the recipient twin receives too much blood.

Keep in mind that is a guide only and each experience could be quite different.

It is important to be aware that TTTS can only develop through a shared placenta, in saying that a shared placenta doesn’t mean it will cause twin to twin transfusion syndrome. Between 10% – 15% of twins who share a placenta will be affected with severity differences.

Symptoms & Signs – Twin to Twin Transfusion Syndrome


An ultrasound is usually one of the first signs of this transfusion issue. A twins ultrasound will determine if they are sharing a placenta, monochorionic twins, and if there is an unusual growth difference, aka growth discordance.


Other Warning Signs Include:

  • Amniotic fluid is uneven, one sac has more than the other
  • The donor twin is small for gestational age and the recipient twin is large for gestation. There is about 10-20% difference in size between them
  • A Uterus measuring large for gestation
  • Expectant mother has sudden weight gain
  • Has the feeling of rapid growth of the womb
  • A thin dividing membrane between the twins
  • Pain or tightness in the abdomen
  • Water in the body of one or both baby’s due to heart failure, called Hydrops Fetalis
  • One baby has a small amount of amniotic fluid and the recipient twin may have too much

Early detection of placenta sharing is necessary so your twin pregnancy can be watched very closely. Frequent ultrasounds and visits to your health care professional are vital in detecting TTTS as early as possible.


How Twin to Twin Transfusion Occurs


TTTS is something that can happen during any twin pregnancy when they share a placenta, it’s a case of timing of when the egg split, and how the vessels in the placenta have connected.


TTTS can happen during anytime of the pregnancy. It’s not genetic or hereditary, it just one of those things that happen randomly. There is no prevention for this.

Treatment of TTTS


Treatment During Pregnancy


Depending on when the twins are affected and what stage in the pregnancy you are, will determine the course of action. Treatments for TTTS include:

  • Regular ultrasounds will be carried out to monitor the growth and well being of the two babies.
  • If your pregnancy is far enough along for viability of the twins then a c-section may be done. This is ultimately the only cure.
  • An operation can be done in the womb using a laser to seal off some or all of the blood vessels that are shared. This can sometimes cause further complications.
  • Amnioreduction, which is a procedure to restore a normal level of amniotic fluid the recipient twin, this is performed placing a needle in to drain the excess fluid

Treatment After Birth

Treatment after delivery will depend on each babies needs. The donor twin maybe anemic, and need a blood transfusion but only in severe cases. The recipient twin may need a reduction in body fluids and have excess red blood cells; Jaundice may need to be treated. Treatment for heart failure maybe need. There will most likely be some time spent in the NICU.

Different Types – Twin to Twin Transfusion Syndrome


Chronic TTTS is more common than Acute twin to twin transfusion syndrome. Between 15 and 20 weeks gestation is usually when this is diagnosed. Symptoms (as above) can be identified.


Acute TTTS usually happens very quickly without much warning and after the 30th week of pregnancy. This can also occur during labor and even in between the birth of twin A and B.


Twin to twin transfusion syndrome can happen at any time during a twin pregnancy.

The TTTS Foundation
For more support with families of TTTS Twins go to:

Have you got any further questions, then check out our FAQs for a Twin Pregnancy

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