Defining Disc Biopsy Timing in Relation to Blood Culture Results for Inpatients with Suspected Discitis-Osteomyelitis.

PURPOSE: To determine optimal timing of biopsy for suspected discitis-osteomyelitis (DOM) with respect to preliminary blood culture results and the effect of biopsy timing on hospital length of stay (LOS).

MATERIALS AND

METHODS

This retrospective study reviewed disc/vertebral biopsies for suspected DOM performed between 2010 and 2018. A total of 107 disc/vertebral biopsies were performed on 96 inpatients (mean ± SD age 57.9 ± 14.5 years, 68 men/28 women) for suspected DOM, and 100 cases of DOM were clinically confirmed and treated. Descriptive and regression statistics were performed with LOS as the primary outcome.

RESULTS

Of disc biopsies in clinically confirmed cases, 68% were positive; 20% of all biopsies had preliminary positive blood cultures after 2 hospital days. There was no difference in LOS between cases with biopsy performed ≤ 2 days after blood culture and cases with biopsy performed > 2 days after blood culture (P = .40). Regression analysis showed no association between positive biopsy results and sepsis, white blood cell (WBC) count, erythrocyte sedimentation rate (ESR), or C-reactive protein (CRP). Biopsy yield was not significantly decreased in patients previously taking antibiotics (P = .09).

CONCLUSIONS

Waiting 2 days for preliminary blood culture results could avoid disc/vertebral biopsy in 20% of patients and does not significantly impact hospital LOS. Additionally, clinical factors (sepsis, WBC count, CRP, and ESR) do not have predictive value for positive disc biopsy results.