Infectious discitis diagnostic contribution of laboratory tests and percutaneous discovertebral biopsy

Clinical and laboratory findings in 120 patients with suspected discitis (loss of disk height and erosions of the vertebral endplates on plain radiographs) were reviewed and compared with percutaneous discovertebral biopsy results. Patients were categorized into three groups based on whether the symptoms developed after an invasive procedure (Group I), during septicemia (Group II), or spontaneously (Group III). Group II patients were more likely to have fever and had higher mean erythrocyte sedimentation rate and C-reactive protein values. A pathogen was recovered in the biopsy specimen in 34%, 60.7%, and 43.5% of patients in groups I, II, and III, respectively. Specific histologic changes were seen in 49%, 42.8%, and 51.3% of cases, respectively. The combination of clinical, laboratory test, and biopsy findings established the diagnosis of pyogenic discitis in 74 cases (62.5%), tuberculous discitis in nine cases (7.5%), and degenerative pseudodiscitis in 37 cases (30%). Percutaneous biopsy had a sensitivity of 72% and a specificity of 94%. Percutaneous discovertebral biopsy is helpful for the diagnosis of infectious discitis and should be done whenever this condition is suspected.