How is a discogram actually done?

With you conscious . This is a test that you have to verbally respond to when placed on a table that x-rays pass through & a needle is guided sterilely into the disc under local anesthesia with some light IV sedation & confirmed to be in the right place with contrast injected followed by sterile water to see what response is given as to whether the disc is the cause of pain. A normal disc does not have pain elicited.
Doscogram. After sedation they will position you on a table and use fluroscope to guide placement into a target disc and one or two control discs pressurize them with a saline solution they should record pressures and look for leaking contrast on a post procedure ct scan but recording your pain response is most importantpart normal discs dont hurt when injected the painful disc will they are looking for.