In brief — the direct answer
Radiofrequency ablation uses a needle-based device to stop circulation to one fetus in selected complicated shared-placenta pregnancies. It may be discussed for TRAP or other severe conditions after specialist assessment. Counselling must address the reason, alternatives and risks to the remaining twin and the pregnancy; benefit is not guaranteed.
What is Radiofrequency Ablation (RFA)?
RFA differs from laser surgery in how the energy is delivered.
While a laser uses light to seal vessels on the *surface* of the placenta, RFA uses a specialized needle (electrode) inserted directly into the base of the umbilical cord. When the device is activated, the tip of the needle generates thermal energy that causes the blood inside the vessel to coagulate instantly, creating a permanent seal. This is particularly effective for larger blood vessels where a laser might not be sufficient.
Who is at risk?
RFA is most commonly used for:
- TRAP Sequence: To stop the blood flow to an acardiac (non-viable) twin that is straining the heart of the healthy 'pump' twin.
- Complex Reduction: In selective fetal growth restriction (sFGR Stage III) or when one twin has a severe, non-correctable anomaly, and the shared placenta puts the healthy twin at a 30-40% risk of brain injury or death if their sibling passes away naturally.
How we diagnose it
Selection for RFA requires high-level Doppler assessment:
- Vessel Mapping: Using color Doppler to find the precise entry point into the target twin's umbilical cord.
- Distance Assessment: Ensuring there is enough space to perform the ablation without affecting the healthy twin's circulation.
- Maternal Readiness: Evaluation for local anesthesia suitability.
What does management involve?
The procedure is carried out in our fetal therapy unit:
- Targeting: Under ultrasound guidance, a 17-gauge RFA needle is passed through the mother's abdomen into the heart or umbilical cord base of the target twin.
- Cycles: Thermal energy is applied in short 'bursts' for several minutes. The surgeon monitors the temperature and the effect on the blood flow in real-time on the ultrasound screen.
- Confirmation: Once the Doppler shows that the blood flow has completely stopped, the needle is withdrawn.
- Aftercare: The mother is observed for a few hours. The healthy twin is monitored for any signs of transient heart rate changes.
What are the outcomes?
The potential benefit and risk depend on the diagnosis, gestation, technique and condition of the other twin. A procedure does not guarantee survival or freedom from neurological injury. Discuss the possibilities of losing one or both twins, membrane rupture, prematurity and further intervention, together with the alternatives. Published results from selected series must not be presented as this unit’s audited outcomes. Ongoing ultrasound and appropriate postnatal follow-up remain important.
When to see a subspecialist
If you have a monochorionic twin pregnancy with a severe diagnosis affecting one twin, you should be referred to a center with RFA capabilities immediately.
RFA is a technically demanding procedure that requires a high volume of fetal therapy cases to maintain safety. Dr. Werner Diehl has extensive experience with the physics and application of RFA in fetal medicine, offering families a safe and controlled option during these incredibly difficult clinical scenarios.