The results of laboratory tests can be equivocal. The white cell count is elevated in only 42% of patients and often is normal. Both blood and spinal cultures may also be negative. Blood cultures are accurate in only 25% of cases, and closed biopsy techniques are diagnostic in only 70% of cases. The ESR rate is elevated in more than 90% of patients, and the C-reactive protein level (CRP) is also elevated at an earlier point in the infectious process. However, both of these tests are systemic indicators of inflammation and are relatively nonspecific. Thus, there is often a significant delay in diagnosis because many of the signs and symptoms of pyogenic vertebral osteomyelitis are subtle. Clearly, the diagnosis relies on having a high index of suspicion in at-risk patients as well as initiating the appropriate evaluation that will identify the organism and determine the extent of infection
