A discogram is a diagnostic imaging test that helps to determine whether a specific intervertebral disc may be the source of back or neck pain. Intervertebral discs are found between the bodies of vertebrae and act as a shock absorber for the spine while providing flexibility. When a disc bulges or ruptures, or is affected by a degenerative condition, the inner gel-like nucleus can leak out of the disc and press on the nerves of the spine, causing pain or weakness in different parts of the body, depending on where in the spine the disc is located.