OHSU

Cavernous Sinus Sampling Test for Cushing's Disease

Cushing's disease can be difficult to diagnose. This is because adrenocorticotropic hormone (ACTH) levels are high. High levels of ACTH can be a sign of Cushing's disease, but can also be caused by other tumors or conditions outside your pituitary gland.  

A test called cavernous sinus sampling (CSS) helps your doctor diagnose a pituitary tumor causing Cushing's disease. This test is almost 100 percent accurate. It can show which side of your pituitary gland the tumor is located, even when a magnetic resonance image does not show the tumor clearly.  

If you have cavernous sinus sampling, a doctor puts catheters (thin, hollow tubes) in the veins of both upper legs. The tubes are guided into your cavernous sinus, an area at the base of your head, behind your eyes. This area has many veins (blood vessels). Your doctor can measure how much blood is flowing away from the pituitary gland on the right and left sides. This gives him or her information about the pituitary tumor.

Cavernous sinus sampling is an outpatient procedure (no overnight hospital stay). During the procedure, you have sedation (medication to help you relax and minimize discomfort). It takes one or two hours. Results are available in one or two days.