Early Minimally Invasive Radiofrequency Ablation for Twin Reversed Arterial Perfusion Sequence at 16 Weeks of Gestation: the First Successful Case in Vietnam

Abstract

Background:

Twin reversed arterial perfusion (TRAP) sequence is a high-risk condition in monochorionic twin pregnancies, in which adverse outcomes of the pump twin are closely related to the duration and magnitude of abnormal perfusion. Early treatment with minimally invasive fetal techniques may reduce procedure-related morbidity and improve pregnancy outcomes.

Objective:

In this case report, we describe the first successful application of early fetal radiofrequency ablation at 16 weeks of gestation for the treatment of TRAP sequence in Vietnam. This report emphasizes the rationale for early intervention, the minimally invasive nature of the procedure, and the favorable clinical outcome, contributing practical insights to contemporary fetal therapy practice.

Case presentation:

We report a case of monochorionic twin pregnancy complicated by twin reversed arterial perfusion (TRAP) sequence, diagnosed and treated at 16 weeks of gestation. Ultrasound and Doppler examination demonstrated persistent reversed arterial perfusion to the acardiac twin without evidence of progressive cardiac failure in the pump twin. Given the early gestational age and the short distance between the umbilical cord insertion of the acardiac twin and the pump twin (approximately 1 cm), intrafetal radiofrequency ablation was performed under continuous ultrasound guidance to occlude the blood supply to the acardiac twin. The procedure was successfully completed with a single percutaneous entry, resulting in immediate cessation of reversed perfusion. No procedure-related complications, including membrane rupture or preterm birth, were observed during follow-up. The patient was managed on an outpatient basis thereafter, and the pregnancy was completed at 37 weeks of gestation with the delivery of a male neonate weighing 2600gram, with Apgar scores of 9 and 10 at 1 and 5 minutes, respectively.

Conclusion:

Early fetal radiofrequency ablation at 16 weeks of gestation is a feasible and minimally invasive treatment option for TRAP sequence. This first reported Vietnamese case highlights the potential benefits of early intervention in reducing invasiveness and procedure-related risks while achieving favorable perinatal outcomes.

1. BACKGROUND

The management of twin reversed arterial perfusion (TRAP) sequence has evolved significantly with advances in prenatal diagnosis and fetal intervention. While the primary therapeutic objective remains the interruption of abnormal blood flow to the acardiac twin, increasing attention has been directed toward the timing and degree of invasiveness of intervention, as these factors may substantially influence both procedural risk and pregnancy outcome (1, 2).. In TRAP sequence, prolonged exposure of the pump twin to reversed arterial perfusion is associated with progressive cardiovascular stress and an increased risk of adverse outcomes. Consequently, interruption of blood flow at an earlier gestational stage before the development of overt signs of cardiac failure has been proposed as a strategy to improve prognosis and facilitate procedural management. Early intervention may also permit the use of smaller-caliber instruments, lower energy delivery, and minimal manipulation within the amniotic cavity (3-5).

Currently, interventional treatment options for TRAP sequence include fetoscopic laser photocoagulation, bipolar cord coagulation, intrafetal radiofrequency ablation, and high-intensity focused ultrasound (1, 2). Among these modalities, radiofrequency ablation offers several advantages that are particularly relevant in early gestation. This technique enables precise energy delivery through a single percutaneous approach, avoids fetoscopic entry, and minimizes disruption of the amniotic membranes. These characteristics may contribute to a reduced risk of procedure-related complications, including preterm premature rupture of membranes, which remains a major concern in fetal surgery. This advantage is especially important in cases where anatomical factors such as a short umbilical cord or close proximity between the acardiac twin and the pump twin limit the feasibility of alternative techniques (6, 7). Although accumulating evidence supports the effectiveness of radiofrequency ablation in the management of TRAP sequence, reports focusing specifically on early gestational intervention remain limited, particularly from low- and middle-income countries (6,7). In Vietnam, fetal intervention for TRAP sequence has been rarely reported, and experience with early fetal radiofrequency ablation has not yet been documented in the international literature.

2. OBJECTIVE

In this case report, we describe the first successful application of early fetal radiofrequency ablation at 16 weeks of gestation for the treatment of TRAP sequence in Vietnam. This report emphasizes the rationale for early intervention, the minimally invasive nature of the procedure, and the favorable clinical outcome, contributing practical insights to contemporary fetal therapy practice

3. CASE PRESENTATION

A 33-year-old pregnant woman, gravida 7 para 0 (including two previous intrauterine fetal demises and five miscarriages), conceived via in vitro fertilization, was referred to our Fetal Intervention Center at Hanoi Obstetrics and Gynecology Hospital. At 16 weeks and 4 days of gestation, she was diagnosed with a monochorionic diamniotic twin pregnancy complicated by twin reversed arterial perfusion (TRAP) sequence, which had been identified from 12 weeks of gestation.

Her medical records were unremarkable. There was no personal or family history of significant medical conditions. Physical examination revealed no abnormal findings. Laboratory investigations at presentation were within normal limits.

Ultrasound findings

Ultrasound examination confirmed a monochorionic diamniotic twin pregnancy with a posteriorly located placenta. The pump twin had an estimated fetal weight of 144 g, a normal deepest vertical pocket of amniotic fluid, and normal Doppler parameters. No structural abnormalities were identified in the pump twin at the time of evaluation.

The acardiac twin measured 45 × 37 mm (Figure 1). It lacked cranial structures and upper limbs, with only the lower trunk and two lower extremities identified. No cardiac activity was observed. The umbilical cord of the acardiac twin contained two vessels. The distance from the umbilical cord insertion to the acardiac twin was approximately 1 mm (Figure 2). Color Doppler imaging demonstrated persistent reversed arterial flow through the single umbilical artery supplying the acardiac twin (Figure 3).

Figure 1. Ultrasound measurement of the acardiac twin.

Figure 2. The distance from the umbilical cord insertion to the acardiac twin.

Figure 3. Color Doppler imaging demonstrated reversed arterial flow through the single umbilical artery supplying the acardiac twin.

The procedure was performed under local anesthesia with lidocaine in our operating room meeting institutional standards for fetal intervention. Amniotic fluid was aspirated for chromosomal analysis. Under continuous real-time ultrasound guidance, a 17-gauge (1.4 mm) radiofrequency ablation needle with a 1.5-cm active tip (Figure 4) was inserted percutaneously through the maternal abdominal wall into the fetal abdomen at the level of the umbilical cord insertion of the acardiac twin (Figure 5).

Figure 4. Radiofrequency ablation system: a: radiofrequency generator; b: 17-gauge radiofrequency ablation needle.

Figure 5. Radiofrequency ablation needle positioned within the acardiac twin.

Radiofrequency energy ranging from 30 to 60 W was applied until cessation of blood flow to the acardiac twin was achieved. Complete interruption of perfusion was obtained after three ablation cycles (30 W, 50 W, and 60 W), each lasting one minute, without technical difficulty. The interval between ablation cycles was approximately 20–30 seconds. Post-procedural ultrasound confirmed absence of vascular flow within the acardiac twin, while cardiac activity and Doppler parameters of the pump twin remained normal (Figure 6).

Figure 6. Post-radiofrequency ablation. a) Doppler ultrasound demonstrating absence of blood flow within the acardiac twin b) normal cardiac activity in the pump twin.

Post-procedural course and follow-up

Oral cephalosporin antibiotics were administered for three days following the procedure. Vaginal progesterone was prescribed to reduce uterine activity. At 24 hours post-procedure, the patient was clinically stable, with no fever, abdominal pain, vaginal bleeding, or fluid leakage. Ultrasound examination demonstrated a stable pump twin with a fetal heart rate of 155 beats per minute, normal Doppler findings, and absence of blood flow in the acardiac twin.

The patient was discharged after three days and followed on an outpatient basis. The pregnancy was monitored every two weeks until 37 weeks of gestation, without evidence of fetal cardiac compromise or polyhydramnios. The acardiac twin gradually regressed and was nearly undetectable by 37 weeks. Spontaneous labor occurred at 37 weeks and 1 day, resulting in the vaginal delivery of a male neonate weighing 2.39 kg, with Apgar scores of 9 and 10 at 1 and 5 minutes, respectively. Only a small residual remnant of the acardiac twin was identified at delivery.Written informed consent was obtained from the patient. The study was approved by the Ethics Committee of Hanoi Obstetrics and Gynecology Hospital.

4. DISCUSSION

Twin reversed arterial perfusion (TRAP) sequence represents a unique therapeutic challenge in monochorionic twin pregnancies, as the prognosis of the structurally normal fetus depends largely on the timely interruption of abnormal placental perfusion rather than correction of fetal anatomy. In recent years, advances in fetal intervention have shifted the management paradigm toward targeted intrafetal procedures, with increasing emphasis on early treatment and procedural safety (1, 8).

A key consideration in the management of TRAP sequence is the timing of intervention. Prolonged exposure of the pump twin to reversed arterial perfusion has been associated with progressive cardiovascular overload, polyhydramnios, and increased risk of fetal demise. Intervention performed at an earlier gestational age, before the development of overt cardiac dysfunction, may therefore reduce hemodynamic stress on the pump twin and simplify procedural management (1, 2, 8). In the present case, treatment was undertaken at 16 weeks and 4 days of gestation, at a stage when the pump twin remained hemodynamically stable and the acardiac twin was relatively small. This timing allowed the procedure to be performed proactively rather than reactively, with the aim of preventing subsequent deterioration.

The choice of treatment modality is another critical factor influencing outcomes. Several techniques have been described for interrupting blood flow to the acardiac twin, including fetoscopic laser photocoagulation, bipolar cord coagulation, and intrafetal radiofrequency ablation (1,2, 9). While fetoscopic approaches have demonstrated efficacy, they typically require larger access ports and greater manipulation of the amniotic cavity, which may increase the risk of membrane-related complications, particularly when performed early in gestation. In contrast, intrafetal radiofrequency ablation can be performed percutaneously using a single small-caliber needle, without the need for fetoscopic entry (1, 10, 11, 12).

In the present case, radiofrequency ablation was selected because of several anatomical and gestational factors. The acardiac twin was small, with an estimated weight of approximately 17 g, and the distance between the umbilical cord insertion of the acardiac twin and the pump twin was extremely short. These features limited the feasibility of alternative techniques targeting the umbilical cord directly and favored an intrafetal approach. The procedure was successfully completed using a single percutaneous entry and relatively low energy delivery, resulting in immediate cessation of reversed perfusion without technical difficulty.

An important advantage of early intrafetal radiofrequency ablation is the potential reduction in procedure-related morbidity. Preterm premature rupture of membranes remains one of the most significant complications of fetal surgery and is closely related to the size and number of membrane punctures as well as the degree of intra-amniotic manipulation (6, 7, 13, 14). In this case, early gestational intervention allowed the use of a small-diameter needle and minimized disruption of the amniotic membranes. No membrane rupture, uterine contractions, or infectious complications were observed during follow-up, and the pregnancy progressed to term with a favorable neonatal outcome (6, 7, 13, 14).

Reports focusing specifically on early radiofrequency ablation for TRAP sequence remain limited, particularly from low- and middle-income countries. Most published series describe intervention performed in the late second trimester, often after the onset of pump twin compromise. Our experience suggests that early intervention, when carefully selected based on fetal and anatomical characteristics, may offer meaningful advantages in terms of procedural simplicity and safety.

This case also reflects the evolving role of fetal intervention services in settings with developing infrastructure. With appropriate training, multidisciplinary coordination, and careful patient selection, advanced fetal therapeutic techniques such as radiofrequency ablation can be safely implemented and may substantially improve outcomes for high-risk monochorionic twin pregnancies.

5. CONCLUSION

Early fetal intervention is crucial in the management of twin reversed arterial perfusion sequence by preventing progressive hemodynamic compromise of the pump twin. This case demonstrates that intrfetal radiofrequency ablation performed at 16 weeks and 4 days of gestation is a feasible and minimally invasive option that effectively interrupts abnormal perfusion with limited procedural manipulation. The favorable outcome observed in this first reported Vietnamese case supports the role of timely fetal intervention in improving perinatal outcomes in high-risk monochorionic twin pregnancies

Ethics statement:

The study was approved by the Ethics Committee of Hanoi Obstetrics and Gynecology Hospital.

Author’s contribution:

Phan Thi Huyen Thuong and Do Tuan Dat contributed to the study concept and design, analysis and interpretation of data, and critical revision of the manuscript. Phan Thi Huyen Thuong and Do Tuan Dat were responsible for data acquisition and performed the fetal radiofrequency ablation procedure. Phan Thi Huyen Thuong, Ngo Thi Huong, Duong Van Vu, Le Thi Anh Dao and Do Tuan Dat contributed to drafting the manuscript. Phan Thi Huyen Thuong and Do Tuan Dat supervised the study. All authors read and approved the final version of the manuscript

Conflict of interest:

Conflict of interest: the authors declare no potential conflict of interest.

Funding:

This study did not receive funding from any individual or organization