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How is TTTS (Twin-to-Twin Transfusion Syndrome) Diagnosed?

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Question: How is TTTS (Twin-to-Twin Transfusion Syndrome) Diagnosed?
Twin-to-Twin Transfusion Sydrome is a disorder that impacts about ten percent of monozygotic (identical) twin pregnancies. Find more answers to Frequently Asked Questions About TTTS.
Answer: Ultrasound technology can be used to detect the development of TTTS (Twin-to-Twin Transfusion Syndrome) in a twin pregnancy. First, the determination of the babies' genders can help doctors establish whether twins are possibly monozygotic. Only same-sex twins (two girls or two boys) are monozygotic, except in extremely rare cases of chromosomal defects. Then, a doctor or radiological technician will examine ultrasound images to determine the number of placentas. When there is a single, shared placenta, further ultrasound monitoring will be conducted. Evidence of the development of TTTS includes:
  • discrepancy between the sizes of the two babies (one significantly larger than the other)
  • too much amniotic fluid (polyhydramnios)in one of the babies
  • or too little amniotic fluid (oligohydramnios) in one of the babies


The severity of TTTS is characterized into five stages. The terminology is referred to as Quintero Staging, named for Dr. Ruben Quintero who developed the process for classifying the condition. They are:
  1. Stage 1: Small amount of fluid detected in the donor baby, while a large amount is detected in the recipient baby.
  2. Stage 2: Along with the symptoms of Stage 1, the donor twin's baby is undetectable on ultrasound.
  3. Stage 3: One or both babies will show evidence of poor blood flow, a sign of a failing circulatory system
  4. Stage 4: Recipient twin exhibits swelling under the skin and appears to be experiencing heart failure from the stress of processing the excess blood.
  5. Stage 5: One of the babies has expired. Generally the donor twin is the first to succumb, but both are at risk. .

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