Preoperative ultrasonography parathyroid gland mapping can improve identification of normal parathyroid gland during thyroidectomy: A propensity score-matched case-control study.

Background: Accurate intraoperative identification of normal parathyroid glands (PTGs) is vital to avoid hypocalcemia post total thyroidectomy. Although ultrasonography (US) has been shown to identify normal PTGs, the significance of preoperative US PTG mapping in this context is not well studied. This study evaluated the impact of preoperative US PTG mapping on intraoperative identification of normal PTGs during total thyroidectomy.

Methods: The study involved 161 consecutive patients who underwent total thyroidectomy between January 2020 and June 2022. These included patients without preoperative US PTG mapping (group 1, n = 91) and those with the mapping (group 2, n = 70). Propensity score matching yielded 61 matched patients from each group. We developed a preoperative US PTG mapping technique combining US identification of normal PTGs with their localization on thyroid CT images. The intraoperative detectability of normal PTGs during thyroid surgery and detectability of normal PTGs by the preoperative US mapping were assessed by the number of PTGs identified per patient and by location.

Results: In the matched cohort, group 2 demonstrated a higher median number of identified PTGs (3 vs. 2, p = 0.011), a greater proportion of patients with three or more identified PTGs (65.5% vs. 44.3%, p = 0.018), and a higher ratio of identified to expected PTGs (70.5% vs. 60.2%, p = 0.011) than group 1. In group 2, the median number of normal PTGs identified preoperatively was 3, with at least one identified in 95.7% of patients, two or more in 84.3%, three or more in 52.9%, and four or five in 24.3%.

Conclusions: Preoperative US PTG mapping identified two or more normal PTGs in the majority of adult patients undergoing total thyroidectomy. Those with preoperative mapping showed a higher number of intraoperatively identified normal PTGs, including inferior PTGs, compared to those without. This technique appears to enhance the intraoperative identification of normal PTGs, thereby potentially improving surgical outcomes in total thyroidectomy.