The C-reactive protein for detection of early infections after lumbar microdiscectomy

The tendency for short hospitalization after lumbar microdiscectomy implies the need for early confirmation or disproval of serious postoperative infections such as spondylodiscitis or deep wound infections. The C-reactive protein (CRP) is a well-known screening parameter for monitoring postoperative infectious complications in other fields. Our objective was to establish the diagnostic significance of CRP-in comparison with ESR and WBC-for monitoring infectious complications after lumbar microdiscectomy. Over a 15 months period we studied prospectively a homogeneous group of N = 400 patients with lumbar disc herniations who were operated on a single level for the first time. CRP, ESR and WBC values were determined in all patients pre-operatively, and on postoperative days 1 and 5. Clinical and laboratory findings were correlated and the diagnostic significance of CRP, ESR and WBC calcualted. N = 385 (96%) patients had an uneventful postoperative course. N = 15 (4%) patients developed infectious complications, of which N = 6 (1.5%) were unrelated and N = 9 (2.5%) related to surgery. Evaluation of the laboratory values showed: The CRP baseline is a very individual value of no prognostic relevance. A high postaggression peak is typical and essential as a reference value for only the future time course will disclose any infection. We found 0% false negative and 4% false positive results on day 5. The sensitivity for serial CRP testing was calculated as 100% and specificity as 95.8%. ESR (sensitivity: 78.1%/specificity: 38.1%) and WBC (sensitivity: 21.4%/specificity: 76.8%) both failed to reach such distinct diagnostic significance on day 5. The C-reactive protein has thus proved to be a reliable, simple and economical screening test for infectious complications after lumbar microdiscectomy, superior to classical laboratory parameters.