Your doctor will normally be able to diagnose a prolapsed disc from the symptoms and by examining you. (It is the common cause of sudden back pain with nerve root symptoms). In most cases, no tests are needed as the symptoms often settle within a few weeks. Tests such as X-rays or scans may be advised if symptoms persist. In particular, an MRI scan can show the site and size of a prolapsed disc. This information is need if treatment with surgery is being considered.