Diagnostic yield of CT-guided percutaneous aspiration procedures in suspected spontaneous infectious diskitis

PURPOSE: To evaluate the diagnostic yield of computed tomography (CT)-guide d percutaneous needle aspiration procedures in the setting of suspected spo ntaneous infectious diskitis and to assess the usefulness of concurrent cyt ologic examination as a supplement to microbiologic evaluation. MATERIALS AND METHODS: A retrospective study was performed to evaluate 105 consecutive CT-guided percutaneous disk space aspiration procedures in 92 p atients suspected of having spontaneous (non-postoperative) infectious disk itis. Our criterion standard for the presence of active infection was the i dentification of a pathogen either from the CT-guided aspiration specimen o r from a surgical specimen. All cases had microbiologic analysis, 78 cases had cytopathologic analysis, and 31 cases had open surgery. RESULTS: Microbiologic analysis of the CT-guided percutaneous aspiration sp ecimens was positive in 39 of 43 cases proved to have active infections, wi th four false-negative and no false-positive cases (sensitivity, 91%; speci ficity, 100%). The false-negative cases were all active fungal infections i dentified from surgical specimens. Adding cytopathologic analysis to microb iologic analysis improved sensitivity but reduced specificity. The most com mon pathogens were species of Staphylococcus, Streptococcus, Candida, and M ycobacterium. All 30 active bacterial infections were identified with the C T-guided procedures, but only five of nine fungal infections were identifie d. CONCLUSION: CT-guided percutaneous needle aspiration is an accurate method for identifying active bacterial disk space infections but is less reliable for identifying fungal infections.