Utility of an intraoperative ultrasound in lateral approach mini-parathyroidectomy with discordant pre-operative imaging.

Objectives of this study were to assess the utility of intra-operative ultrasound to resolve discordant pre-operative imaging prior to a lateral approach mini-parathyroidectomy, by studying prospective case series in a head and neck endocrine unit. Patients with primary hyperparathyroidism due to a single adenoma with discordant pre-operative ultrasound and sestamibi were enrolled. They underwent a further intra-operative ultrasound by a head and neck radiologist with a view to proceed with a mini-parathyroidectomy. The main outcome measure was utility of intra-operative ultrasound compared to operative findings and pre-operative imaging. Secondary measures were complications of mini-parathyroidectomy, operative and ambulatory discharge time. Twenty-two patients underwent surgery with intra-operative ultrasound in the surgical position. The intra-operative ultrasound findings correlated with the operative findings in all cases (100 %). There were 16 inferior adenomas and 6 superior adenomas. Six inferior adenomas were in a retrosternal position, eight were obscured by benign thyroid lesions and a further two reported pre-operatively as superior. Three out of six superior adenomas were reported as inferior pre-operatively as the inferior thyroid artery was inadequately visualised, two were retro-carotid and one was retro-oesophageal. All patients were discharged within 23 h of surgery. There were no unsuccessful focused explorations. Histological analysis confirmed the adenomas. No morbidity (vocal cord palsy, haematoma, hungry bones) was noted. The results indicated that intra-operative ultrasound by a dedicated radiologist is a valuable tool in resolving discordance of pre-operative imaging. Appropriate patient positioning with neck extension and muscle relaxation allows placement of the probe in the obscure retro-carotid and retro-oesophageal locations and unmasks apparent "mediastinal" parathyroids facilitating focused dissection.