The injury-plagued Gumbleton, who has played just five matches for the Bombers since being taken at No.2 in the 2006 NAB AFL Draft, is suffering from a bulging disc in his back.
An orthopaedic surgeon confirmed the diagnosis on Wednesday afternoon, and Essendon medical staff will now meet with specialists to decide on treatment.
"The bulging disc in Scott's back is impinging on nerves," the club's general manager of football operations, Paul Hamilton, told the official Essendon website.
"The decision now lies between taking the conservative approach and giving him a period of rest or having surgery which would sideline him for at least 12 weeks," he said.
Gumbleton did not play a senior game in 2008 after a hamstring injury and a broken collarbone ruined his season. A hamstring complaints also cruelled his debut season, in which he appeared in five matches.
