Radiofrequency Ablation (RFA)

Common related conditions:


What is Radiofrequency Ablation (RFA)?

Radiofrequency ablation (RFA) is a procedure where an alternating current in the radiofrequency range is transmitted via a shielded needle electrode, causing agitation heating and death in tissues.  It is used in situation where selective reduction of one twin is required.

Prior to procedure, we ask mothers to fast (i.e. NOTHING to eat or drink) for at least 8 hours prior to procedure). The mother can also receive intravenous (IV) medication help her to remain relaxed, but not to go to sleep during the procedure. After local anesthesia (freezing injected into the skin), a special needle electrode specifically designed for this procedure is placed under continuous US guidance. The needle tip is positioned within the fetal abdomen or abdominal wall so that all the umbilical vessels are surrounded once instrument is opened. The device is activated using a specific protocol. Confirmation of loss of circulation is then performed with ultrasound Doppler.

These procedures are usually performed before fetal viability (~ 24 weeks), on an outpatient basis. In rare circumstances where performed after viability, the mother is admitted to hospital for a few hours, however can usually go home a couple of  hours after the procedure. In such cases, after viability, we usually suggest giving the mother 2 shots of intramuscular steroids 24 hours apart to help mature the fetal lungs.

For what conditions is Radiofrequency Ablation performed?

RFA is considered an option in identical twin pregnancies (Monochorionic) where there are complications:

  • Severe Twin-to-twin transfusion where there is concern for death of one twin or severe brain damage.
  • Severe cases of growth discordance with abnormal Dopplers or brain anomalies.
  • Severe discordant anomaly both for parental decision or impending damage to normal fetus.
  • Acardiac fetus or TRAP Sequence with polyhydramnios or cardiac overload (1% monozygotic twins).   An acardiac twin is a parasitic twin, who fails to develop a normal heart, and relies on an abnormal circuit with a normal twin to survive. This twin is not able to survive without this circuit, and there is concern for the normal twin’s survival due to cardiac failure.

What are the risks of RFA for the fetus?

As with any intrauterine invasive procedure, there may be short term complications, including preterm labor, rupture of membranes, infection or bleeding. This means that not all such procedures result in one living baby. But, in about 85% of cases, the procedure results in one living baby, born near term, with no permanent handicap.

Because the umbilical cord is completely blocked, this procedure means survival of both babies can never occur.

What are the risks of RFA for the mother?

For an experienced team, this procedure is technically feasible and usually not long, so maternal operative complications are very unusual.

References:

Lee, H., Bebbington, M., & Crombleholme, T. M. (2013). The North American Fetal Therapy Network Registry data on outcomes of radiofrequency ablation for twin-reversed arterial perfusion sequence. Fetal Diagnosis and Therapy, 33(4), 224–9. doi:10.1159/000343223

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