Reoperative parathyroidectomy: Location of missed glands based on a contemporary nomenclature system

Objectives: To evaluate and categorize the locations of missed parathyroid glands found during reoperative parathyroidectomy and to determine any factors associated with these locations. Design: Retrospective cohort study. Setting: Tertiary referral center. Patients: Fifty-four patients who underwent reoperative parathyroidectomy for persistent or recurrent hyperparathyroidism from January 1, 2005, through January 1, 2009. Main Outcome Measures: Location of missed parathyroid glands and their association with continuous variables were analyzed using a Kruskal-Wallis test, and associations between gland location and categorical variables were evaluated using the Fisher exact test. Results: Among 54 patients, 50 abnormal parathyroid glands were identified, resected, and classified as follows: 5 (10%) were type A (adherent to the posterior thyroid capsule); 11 (22%), type B (behind the thyroid in the tracheoesophageal groove); 7 (14%), type C (close to the clavicle in the prevertebral space); 3 (6%), type D (directly over the recurrent laryngeal nerve); 9 (18%), type E (easy to identify; near the inferior thyroid pole); 13 (26%), type F (fallen into the thymus); and 2 (4%), type G (gauche, within the thyroid gland). No demographic, biochemical, or pathological factors were significantly associated with gland location. Among the 43 patients followed up for 6 months, 40 (93%) had documented cures. Conclusions: Missed glands after parathyroidectomy for hyperparathyroidism can be found in standard locations in most cases. A standardized nomenclature system based on the regional anatomy and the embryology of the parathyroid glands can guide a systematic exploration for parathyroid adenomas that are not easily identified and facilitate communication about gland locations.