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.