Thyroid Cyst Ethanol Sclerotherapy

Background and indications

Thyroid cysts and predominantly cystic nodules (> 50% fluid component) are common and generally benign. When they become large and symptomatic (cervical discomfort, dysphagia, cosmetic deformity), ultrasound-guided percutaneous ethanol injection (PEI) is offered as first-line treatment, as an alternative to surgery.

Pre-procedure assessment

Assessment includes thyroid ultrasound confirming cystic or predominantly cystic nature, fluid FNA (cytology to exclude papillary carcinoma with cystic component), and thyroid panel (TSH).

Procedure

Under local anesthesia and ultrasound guidance, cystic content is first aspirated using an 18-20G needle. Then, sterile 95% ethanol is injected into the cavity (volume = 30-50% of aspirated volume, maximum 10-20 mL). Ethanol is left in contact for 2-10 minutes then re-aspirated. Ultrasound monitors ethanol distribution in real time. The procedure takes 15 to 20 minutes and may be repeated after 4-6 weeks if needed.

Results and scientific evidence

Thyroid cyst ethanol ablation offers 80-95% volume reduction at 6 months, with a 75-95% cure rate (complete disappearance or > 50% reduction) after 1-3 sessions (Bennedbaek et al., Journal of Clinical Endocrinology and Metabolism, 2003; DOI: 10.1210/jc.2002-021369). Efficacy is higher for pure cysts compared to mixed nodules.

Risks and complications

Local pain during ethanol injection (30-50%, transient, few minutes), transient dysphonia from recurrent nerve irritation (1-2%, usually complete recovery), cervical hematoma (< 2%). Ethanol must not diffuse outside the cystic cavity; real-time ultrasound monitoring minimizes this risk.

Recovery

Immediate return to activities. Ultrasound follow-up at 1 and 3 months. If partial recurrence, a 2nd session may be offered.

Practical information

The procedure is performed on an outpatient basis. It is performed by an interventional radiologist.