 In patients randomized to open surgery, a 15 mm transverse skin incision is made close to the site of the parathyroid adenoma indicated by sestamibi scintigraphy. In case of an enlarged upper parathyroid or dorsally located lower parathyroid, the incision is made anterior to the sternocleidomastoid muscle SCM whereas for anterior located lower parathyroids a central incision is chosen. 