Objective To compare the efficacy of ultrasound-guided microwave ablation versus thyroidectomy in the treatment of benign thyroid nodules (BTN) and to explore the influencing factors of prognosis.

Methods A total of 282 BTN patients were enrolled and divided into ablation group (treated with ultrasound-guided microwave ablation, n=172) and resection group (treated with thyroidectomy, n=110) based on treatment methods. Perioperative indicators and thyroid function indices before and after surgery were compared between the two groups. Patients were followed up for 1 year and divided into good prognosis group volume reduction rate (VRR)≥80%, n=210 and a poor prognosis group (VRR < 80%, n=72) based on the VRR. Factors influencing the prognosis of BTN patients were analyzed.

Results The ablation group had shorter operative time and hospital stay, less intraoperative blood loss, and lower postoperative Visual Analogue Scale (VAS) scores compared to the resection group (P < 0.05). One month after surgery, serum thyrotropin (TSH) levels were higher, while free triiodothyronine (FT3) and free thyroxine (FT4) levels were lower than preoperative levels in both groups, however, TSH level was lower, and FT3 and FT4 levels were higher in the ablation group compared to the resection group (P < 0.05). Univariate analysis showed that preoperative TSH levels, the proportion of solid nodules, and the proportion of nodules in the risk zone were lower, while preoperative FT4 levels were higher in the good prognosis group compared to the poor prognosis group (P < 0.05). Binary Logistic regression analysis revealed that nodule type, nodule location, preoperative TSH, and preoperative FT4 were all influencing factors for the prognosis of BTN patients (P < 0.05).

Conclusion Compared to thyroidectomy, ultrasound-guided microwave ablation for BTN offers advantages such as less intraoperative blood loss, milder postoperative pain, shorter operative time and hospital stay, and less damage to thyroid function. Preoperative TSH and FT4 levels, nodule type, and nodule location are closely related to the prognosis of BTN patients and should be given attention in clinical practice.