Twin-to-Twin Transfusion Syndrome: Early Treatment Saves Lives

Twin-to-Twin Transfusion Syndrome (TTTS) causes an uneven blood supply between identical twins sharing a placenta. Early monitoring and treatment can help save both babies.

Twin-to-Twin Transfusion Syndrome (TTTS) is a rare but serious pregnancy complication that affects identical twins sharing a single placenta. It occurs when blood flow between the babies becomes unbalanced, causing one twin to receive too little blood while the other receives too much (1^✔ ✔Trusted Source
Twin-to-Twin Transfusion Syndrome (TTTS)

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Twin-to-Twin Transfusion Syndrome

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Early diagnosis through regular ultrasound scans and timely treatment can greatly improve the chances of healthy outcomes for both babies.

What Is Twin-to-Twin Transfusion Syndrome (TTTS)?

Twin-to-Twin Transfusion Syndrome is a complication that occurs only in monochorionic (shared placenta) twin pregnancies.

In these pregnancies, both babies share blood vessels within the placenta. If these blood vessel connections do not distribute blood evenly, one baby (the donor twin) pumps more blood than it receives, while the other (the recipient twin) receives too much blood.

TTTS develops in about 9% to 15% of monochorionic twin pregnancies, making it one of the most common complications of pregnancies where twins share a placenta. Left untreated, severe TTTS can threaten the lives of one or both babies (2^✔ ✔Trusted Source
Twin-to-Twin Transfusion Syndrome

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Why Does TTTS Develop Between Twins?

TTTS develops because of abnormal blood vessel connections inside the shared placenta. These connections allow blood to flow unevenly between the twins instead of being shared equally.

This imbalance affects both babies differently.

The donor twin may:

• Receive too little blood and oxygen.
• Produce less urine, leading to low amniotic fluid (oligohydramnios).
• Grow more slowly because of reduced nutrients.
• Be at risk of poor organ function if the condition becomes severe.

The recipient twin may:

• Receive too much blood.
• Produce excess urine, leading to too much amniotic fluid (polyhydramnios).
• Have an overworked heart because it must pump extra blood.
• Develop heart failure or other heart-related complications if untreated.

These changes can become progressively worse if the blood flow imbalance is not corrected.

What Signs Should Parents and Doctors Watch For?

Most pregnant women with TTTS may not notice any symptoms in the early stages. This is why regular prenatal ultrasound scans are essential for monochorionic twin pregnancies. (3^✔ ✔Trusted Source
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However, some parents may experience:

• Rapid enlargement of the abdomen.
• Tightness or discomfort in the uterus.
• Sudden weight gain.
• Abdominal pain or contractions.
• Breathlessness caused by excess amniotic fluid.

Doctors may suspect TTTS if ultrasound scans show:

• One baby surrounded by too much amniotic fluid and the other by too little.
• A difference in bladder size between the twins.
• Abnormal blood flow on Doppler ultrasound.
• Signs of heart strain in the recipient twin.
• Weakening or shortening of the cervix, increasing the risk of premature labour.

Mothers with TTTS require close monitoring because excess amniotic fluid can increase the risk of preterm labor and early delivery (4^✔ ✔Trusted Source
Twin-to-Twin Transfusion Syndrome

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How Is TTTS Diagnosed and Monitored?

Doctors usually diagnose TTTS using ultrasound after confirming that the twins share one placenta.

Additional tests may include:

• Doppler ultrasound to assess blood flow.
• Measurement of amniotic fluid around each baby.
• Checking whether the donor twin’s bladder is visible.
• Fetal echocardiography to examine the babies’ hearts when needed.

Monochorionic twin pregnancies should usually be monitored with ultrasound every two weeks from around 16 weeks of pregnancy to detect TTTS as early as possible. Doctors also use the Quintero staging system to determine how severe the condition is and to guide treatment decisions.

How Do Doctors Classify the Severity of TTTS?

Doctors use the Quintero staging system to classify how severe Twin-to-Twin Transfusion Syndrome has become. The staging is based on ultrasound findings and helps guide treatment decisions.

• Stage I (Mild): The recipient twin has too much amniotic fluid, while the donor twin has too little. The donor twin’s bladder is still visible, showing that it is producing urine.
• Stage II (Moderate): The donor twin’s bladder is no longer visible on ultrasound, suggesting it has stopped producing urine because of reduced blood flow.
• Stage III (Advanced): Blood flow abnormalities are seen on Doppler ultrasound in one or both twins, showing that the condition is becoming more serious.
• Stage IV (Severe): One or both babies develop hydrops, a dangerous build-up of fluid in different parts of the body caused by heart failure or severe circulatory problems.
• Stage V (Most Severe): One or both twins die in the womb because of the complications of TTTS.

The Quintero staging system provides a standard way for healthcare providers to assess the severity of TTTS and choose the most appropriate treatment.

However, doctors also consider factors such as the stage of pregnancy, heart function, maternal symptoms, and access to specialized fetal treatment centers before deciding on the best management plan.

How Is Twin-to-Twin Transfusion Syndrome Treated?

Treatment depends on how severe TTTS is and how far the pregnancy has progressed.

Treatment options include:

• Close monitoring for mild or stable cases with frequent ultrasound scans.
• Fetoscopic laser surgery, the standard treatment for most Stage II to Stage IV TTTS diagnosed between 16 and 26 weeks. During this minimally invasive procedure, doctors use a tiny camera and laser to seal the abnormal blood vessels inside the placenta, helping restore a more balanced blood supply between the twins.
• Amnioreduction, where excess amniotic fluid is drained from around the recipient twin to reduce pressure and relieve symptoms. This helps manage the condition but does not correct the underlying blood vessel imbalance.
• Septostomy may be considered in selected cases, although it is less commonly used.
• Early delivery may be recommended if the babies are mature enough or if continuing the pregnancy becomes unsafe.

Fetoscopic laser surgery has become the preferred treatment because it significantly improves survival compared with older approaches (5^✔ ✔Trusted Source
Management of twin‐to‐twin transfusion-syndrome: update and current challenges

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).

Recent evidence shows that after laser treatment, around 90% of pregnancies have at least one surviving baby, while about 65% to 70% result in the survival of both twins, although outcomes depend on the stage of TTTS and gestational age at diagnosis.

What Should Parents Know About TTTS?

TTTS cannot usually be prevented because it develops randomly in pregnancies where identical twins share a placenta. It is not caused by anything the parents did or did not do.

Parents should remember to:

• Attend every scheduled prenatal ultrasound appointment.
• Report sudden abdominal enlargement, pain, contractions, or breathlessness to their healthcare provider.
• Seek care from a maternal-fetal medicine specialist or fetal therapy center if TTTS is suspected.
• Discuss treatment options, possible outcomes, and long-term follow-up with their healthcare team.

Although TTTS remains a serious condition, advances in fetal monitoring and laser surgery have greatly improved outcomes over the past two decades. According to Cleveland Clinic, Johns Hopkins Medicine, and ISUOG, early diagnosis, specialist care, and timely treatment offer the best chance of protecting both babies and improving pregnancy outcomes.

References:

1. Twin-to-Twin Transfusion Syndrome (TTTS) – (https://www.hopkinsmedicine.org/health/conditions-and-diseases/twintotwin-transfusion-syndrome-ttts)
2. Twin-to-Twin Transfusion Syndrome – (https://www.ncbi.nlm.nih.gov/books/NBK563133/)
3. Twin-Twin Transfusion Syndrome – (https://www.isuog.org/education/visuog/obstetrics/multiple-pregnancy/twin-twin-transfusion-syndrome.html)
4. Twin-to-Twin Transfusion Syndrome – (https://my.clevelandclinic.org/health/diseases/22985-twin-to-twin-transfusion-syndrome)
5. Management of twin‐to‐twin transfusion syndrome: update and current challenges – (https://www.sciencedirect.com/science/article/abs/pii/S2589933325001144)

Source-Medindia