From the Guidelines
The treatment approach for Twin Reverse Arterial Perfusion (TRAP) sequence in pediatric patients involves early intervention to protect the viable "pump" twin, with the primary treatment options including fetoscopic laser coagulation, radiofrequency ablation (RFA), or umbilical cord occlusion to interrupt blood flow to the acardiac twin, as recommended by the most recent guidelines 1.
Treatment Overview
The goal of treatment is to prevent high-output cardiac failure in the viable fetus by stopping the pump twin from providing circulation to the acardiac twin.
- The procedure typically involves inserting a needle through the maternal abdomen under ultrasound guidance to ablate the blood vessels supplying the acardiac twin.
- The timing of intervention is critical, with treatment usually performed between 16-24 weeks gestation, and some authors suggesting earlier elective intervention may be beneficial, particularly if the TRAP is large 1.
Monitoring and Delivery
After intervention, close monitoring with serial ultrasounds is essential to assess fetal growth and cardiac function.
- The timing of delivery depends on fetal well-being, but often occurs at 34-37 weeks gestation.
Important Considerations
It is essential to note that TRAP sequence is a prenatal condition that either resolves with intervention before birth or results in the death of the pump twin if untreated, and therefore, it is not treated postnatally in pediatric patients.
- The condition occurs when an abnormal twin without a functioning heart (acardiac twin) receives blood from the normal "pump" twin through abnormal arterial-arterial anastomoses, placing the pump twin at risk for high-output cardiac failure. While other studies discuss various prenatal conditions and their treatments, such as nonimmune hydrops fetalis 1, the most recent and relevant guideline for TRAP sequence is the 2024 update from the Journal of the American College of Radiology 1.
From the Research
Treatment Approaches for Pediatric TRAP Sequence
The treatment approach for Twin Reverse Arterial Perfusion (TRAP) sequence in pediatric patients involves various methods to manage the condition and prevent complications. Some of the treatment approaches include:
- Fetoscopic laser photocoagulation of the acardiac twin's umbilical cord, which has been shown to be effective in maintaining the pregnancy and allowing for the birth of a healthy pump twin 2
- Radiofrequency ablation to stop perfusion to the acardiac twin and protect the pump twin, with a reported survival rate of 86% for the pump twin 3
- Selective nonsurgical interventions, such as indomethacin, digitalis, and tocolysis, which may be used to manage the condition and prevent complications 4
- Surgical interventions, such as hysterotomy with selective delivery of the acardiac twin or ligation of the acardiac twin's umbilical cord, which may be necessary in some cases 4
Factors Affecting Treatment Outcomes
The outcome of treatment for TRAP sequence depends on various factors, including:
- The presence of morphological abnormalities in the acardiac twin, such as a single umbilical artery or chromosomal abnormalities 4
- The development of polyhydramnios and preterm labor, which can increase the risk of complications for the pump twin 4
- The ratio of the weight of the acardiac twin to the weight of the pump twin, with a higher ratio indicating a greater risk of complications 2
- The presence of cardiac failure in the pump twin, which can increase the risk of mortality 3, 5
Importance of Early Detection and Treatment
Early detection and treatment of TRAP sequence are crucial to prevent complications and improve outcomes for the pump twin. The use of 3-dimensional volume and color Doppler sonography can aid in the detection of TRAP sequence at the time of first-trimester screening 6. Prompt treatment, such as cord occlusion, can improve survival rates for the pump twin and reduce the risk of complications 6.