Free Editor Choice with CME: Transsphenoidal Surgery After Nondiagnostic IPSS

Background: Inferior petrosal sinus sampling (IPSS) is a useful technique for confirming a pituitary source of adrenocorticotropic hormone (ACTH) overproduction in Cushing disease. Uncertainty remains regarding the appropriate course of therapy when an ectopic tumor is predicted by IPSS but none can be found and in circumstances when the procedure cannot be successfully completed owing to technical or anatomic limitations.

Objective: To determine an appropriate course of action after nondiagnostic IPSS.

Methods: We reviewed 288 IPSS procedures in 283 patients between 1986 and 2010 at our center. An IPS:peripheral ACTH ratio ≥ 2 at baseline or ≥ 3 after corticotrophin-releasing hormone was considered predictive of a pituitary source of ACTH. A procedure was considered nondiagnostic if the procedure was successfully performed and the results predicted an ectopic source but none could be found despite extensive imaging or if the IPS could not be bilaterally cannulated because of technical difficulties or anatomic variants.