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TRAP Sequence (Twin Reversed Arterial Perfusion)

A rare and life-threatening complication seen in monochorionic twins where one fetus's heart fails to develop.

Written by: Saygı Hospital Health Guide Editorial Board
Last updated:

This content has been compiled by the Saygı Hospital Health Guide Editorial Board and is periodically reviewed by a specialist physician.

This content is for informational purposes only and does not constitute medical advice. You can book an appointment at our Kadın Hastalıkları ve Doğum department. Book Appointment →

What is TRAP Sequence (Twin Reversed Arterial Perfusion)?

TRAP sequence occurs only in monochorionic twin pregnancies and affects approximately 1% of all monochorionic pregnancies. Through artery-to-artery anastomoses in the placenta, the normal 'pump' twin sends blood in reverse direction to the acardiac twin.

In the acardiac twin, the heart is structurally absent or severely deformed. The upper extremities and head fail to develop. Perfusion depends entirely on the pump twin and over time may cause increased cardiac load and heart failure in the pump twin.

Management focuses on reducing the risk of heart failure in the pump twin through cord occlusion of the acardiac twin (radiofrequency ablation, laser, or fetoscopic cord occlusion). Early intervention improves pump twin survival.

Symptoms

Acardiac twin appearance on ultrasound
Polyhydramnios in pump twin
Cardiomegaly in pump twin
Findings of hydrops
Abnormal Doppler flow
Early contractions in mother
Intrauterine fetal loss

Risk Factors

Monochorionic twin pregnancy
Placental vascular anastomosis architecture
Abnormal cleavage of the early zygote
IVF and assisted reproductive techniques
Family history of twins
Polyhydramnios

When to See a Doctor?

If you experience any of the following symptoms, seek medical attention promptly:

  • During regular ultrasound checks in monochorionic twin pregnancy
  • When a twin without heartbeat is detected on ultrasound
  • When polyhydramnios develops
  • When the pump twin's cardiac function deteriorates
  • With signs of preterm labor

Treatment Methods

01
Maternal-fetal medicine follow-up from the second trimester
02
Radiofrequency ablation (acardiac cord)
03
Fetoscopic laser or bipolar cord occlusion
04
Corticosteroids and fetal lung maturation
05
Cardiac monitoring of the pump twin
06
Timed delivery and intensive care

Which Department to Visit?

You can visit our Kadın Hastalıkları ve Doğum department for these complaints. Our specialist physicians will create the most suitable treatment plan for you.

Learn About Kadın Hastalıkları ve Doğum Department

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Health Disclaimer: The information on this page is prepared for general informational purposes only. It does not replace medical diagnosis and treatment. Please consult your physician for your complaints. Saygı Hospital does not accept responsibility for actions taken based on the information on this page.