Twin Reversed Arterial Perfusion, also known as TRAPS or Acardiac Twin Pregnancy, is a rare but serious complication of monochorionic twin pregnancies, where twins share a single placenta and blood vessels. Dr Tejas Tamhane, a top-rated fetal medicine specialist, offers expert care for complex conditions like the TRAP sequence.
What Is Twin Reversed Arterial Perfusion?
Twin reversed arterial perfusion sequence (TRAPS) is a rare condition that occurs only in twins who share a placenta (monochorionic). In this, one fetus, called an acardiac or parasitic twin, doesn’t develop a functioning heart (or has a deformed heart and body parts) and instead receives blood from the other twin, who is developing normally.
This normal twin is known as the “pump twin” because its heart is doing all the work for both. This extra burden can put a lot of strain on the pump twin’s heart, increasing the risk of cardiac failure. Meanwhile, the acardiac twin continues to grow but in an abnormal way. Since it isn’t receiving properly oxygenated blood, it can develop severe deformities. Sadly, it is not viable for life after birth, no matter what interventions are done.
TRAP sequence is incredibly rare, occurring in about 1% of monochorionic twin pregnancies. But when it does happen, it can be dangerous for the pump twin if left untreated. The extra workload on the heart, combined with the risk of preterm labour, makes early diagnosis and intervention very important for a healthy birth.
What Happens If The TRAP Sequence is Left Untreated?
Unfortunately, the TRAP sequence is a life-threatening complication. Here’s what could happen if TRAP is left untreated:
- Cardiac failure in the pump twin
The excess pressure on one twin can weaken the pump twin’s heart, increasing the risk of fetal death.
- Polyhydramnios
Too much amniotic fluid can build up, leading to complications such as preterm labour.
- Preterm birth
The pregnancy might end too early, increasing risks for the pump twin.
- Stillbirth
If the pump twin’s heart can’t keep up, it may not survive.
Diagnosis of Twin Reversed Arterial Perfusion (TRAP) Sequence
Most cases of TRAP sequence are detected through sonography during the first trimester. Your fetal medicine specialist will look for any of these key signs:
- One normally developing fetus and another with abnormal cardiac activity.
- Abnormal blood flow pattern between the twins
- Differences in size and development
- Excess amniotic fluid (polyhydramnios)
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Treatment Options for TRAP Sequence
How the other twin is developing and the amount of strain the pump twin is under determine how the TRAP sequence is treated.
1. Close Monitoring: The doctor will just monitor the pregnancy closely if the acardiac twin is small and not growing significantly. Making sure the pump twin is not displaying any signs of distress is the goal here.
2. Foetal Intervention: A foetal operation to stop the blood flow can be performed if the acardiac twin is growing too much or is putting too much burden on the pump twin. Radiofrequency ablation, cord ligation and laser ablation are a few techniques for this purpose.
3. Delivery Planning: Doctors may advise an early delivery if the pump twin is experiencing problems but has reached a viable gestational age.
Twin Reversed Arterial Perfusion (TRAP) Sequence – Reach Out To Dr Tejas
The health of the pump twin depends on prompt detection and treatment for the uncommon but dangerous TRAP sequence. The good news is that many pump twins are born healthy thanks to advancements in foetal medicine, fetal interventions and proper care. We can help if you or someone you know has been diagnosed with TRAP. Do you need support or have questions? Do not hesitate to contact Pune’s top fetal medicine expert, Dr Tejas Tamhane.
