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Twin Anemia Polycythemia Sequence (TAPS)

What is twin anemia polycythemia sequence?

Twin anemia polycythemia sequence (TAPS) is a rare type of TTTS, or twin-to-twin transfusion syndrome. This condition impacts monochorionic pregnancies, which occurs when twins share one placenta and a network of blood vessels. TAPS causes the twins to have unequal blood counts while in the womb, leading to one twin receiving less oxygen and nutrients. The twin who loses blood is called the donor twin and is at a high risk of anemia. The other is the recipient twin and is at an increased risk of polycythemia. 

What are the symptoms of twin anemia polycythemia sequence?

Symptoms include:

  • Thick blood in the recipient twin
  • Anemia in the donor twin
  • Polycythemia in the recipient twin
    • Leads to slowed blood flow
    • Possibly causes thrombosis

What causes twin anemia polycythemia sequence?

This condition occurs when a low number of small caliber artery-to-vein vessel connections join together. They typically sit by the edge of the placenta. 

There are risk factors for this condition: prior laser surgery for TTTS and a monochorionic pregnancy. 

How is twin anemia polycythemia sequence diagnosed?

Two conditions must be met in order to receive a TAPS diagnosis:

  1. Fast blood flow and anemia in the donor twin
  2. Slow blood flow and polycythemia in the recipient twin

A special type of ultrasound, Doppler, detects both of these things. A diagnosis can be confirmed by decreased blood flow in one fetus’ middle cerebral artery and increased blood flow in the other’s. The Leiden staging system is also used in diagnosis, categorizing one’s condition on a scale of one to five. 

What are the treatments for twin anemia polycythemia sequence?

The health of both the mother and fetuses influence treatment the most. At times, monitoring is all that is necessary. A blood transfusion to the twin with anemia is a treatment option, as is fetal laser surgery to separate the blood vessels. 

If the condition is not detected until after birth, treatment consists of fixing any complications with blood imbalance, which may mean a blood transfusion for the anemic twin. 

Where can I find out more about twin anemia polycythemia sequence?

TAPS Articles