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Radiology
Radiofrequency Ablation
Built from Obstetric Imaging
What’s inside
8 sections · 69 slides
Overview
- Radiofrequency ablation: definition
- Topics covered
Background and rationale
Why monochorionic twins cannot be treated like any other twin pair
- Monochorionic placentation and shared circulation
- Consequences of spontaneous single twin demise
- Events after spontaneous demise of one monochorionic twin
- Contraindication to intracardiac potassium chloride
- Goal of selective reduction in monochorionic gestations
- Development of radiofrequency ablation
- Monochorionic problems that may need selective reduction
- Twin reversed arterial perfusion sequence and the pump twin
- Evidence base for other monochorionic indications
The procedure
Physics, equipment, step-by-step technique and aftercare
- Physical principle of radiofrequency ablation
- Radiofrequency circuit during ablation
- Mechanism of tissue coagulation necrosis
- Design of the radiofrequency probe
- Radiofrequency generator front panel
- Reading the generator during ablation
- Needle electrode with radial tines
- Choice of needle: tines versus no tines
- Gestational age window for the procedure
- Anaesthesia and procedural setting
- Equipment laid out before starting
- Equipment for Radiofrequency Ablation Procedure
- Equipment for Radiofrequency Ablation Procedure (continued)
- Preparation and antibiotic prophylaxis
- Ultrasound survey before needle insertion
- Choosing the intrafetal target site
- Skin incision and needle path
- Needle entering the abdominal wall of the target fetus
- Deploying the tines and delivering energy
- Ablation probe in the fetal abdominal wall with tines deployed
- Thermal energy released at the target site
- Confirming technical success
- Gas bubble artefact after coagulation
- Blood flow convective cooling effect
- Steps of the radiofrequency ablation procedure
- Immediate care after the procedure
- Persistent bradycardia after successful ablation
- Surveillance after the procedure
- Recovery of the cotwin and the role of fetal MRI
Indications and contraindications
Who the procedure is offered to, and when it must not be done
- Indications for radiofrequency ablation
- Contraindications to radiofrequency ablation
Benefits, risks and cost
What is gained, what can go wrong, and what it costs
- Benefits of the procedure
- Procedure-related obstetric risks
- Membrane, placental and infective complications
- Rupture of membranes risk compared with other techniques
- Risks to the nontargeted fetus
- Maternal risks
- $1900
Outcomes in TRAP sequence
The largest and most consistent body of evidence for RFA
- Single-centre series of 29 TRAP pregnancies
- Series of 13 consecutive TRAP cases
- Selection criteria in a series of 17 TRAP pregnancies
- Outcomes in the series of 17 TRAP pregnancies
- Intrafetal ablation compared with cord occlusion
- Two treatment families in the 71 reported TRAP cases
- North American Fetal Therapy Network registry
Other complicated monochorionic pregnancies
Extrapolating the TRAP experience, and what the review data show
- Systematic review of selective termination techniques
- Survival by technique in the systematic review
- Reading the survival comparison
- Gestational age at intervention and survival
Summary and references
What to carry away, and where the evidence still falls short
- Where radiofrequency ablation stands
- Key points: technique
- Key points: indications and contraindications
- Key points: risks
- References
- References (continued)
- References (continued)
- Suggested reading
- Obstetric Imaging: Fetal Diagnosis and Care, 2nd Edition