Estimating the incidence of suspected epidural hematoma and the hidden imaging cost of epidural catheterization: a retrospective review of 43,200 cases.

BACKGROUND AND OBJECTIVES: Hematoma associated with epidural catheterization is rare, but the diagnosis might be suspected relatively frequently. We sought to estimate the incidence of suspected epidural hematoma after epidural catheterization and to determine the associated cost of excluding or diagnosing an epidural hematoma through radiologic imaging.
METHODS: We conducted an electronic retrospective chart review of 43,200 patient charts using 4 distinct search strategies and cost analysis, all from a single academic institution from 2001 through 2009. The charts were reviewed for use of radiologic imaging studies to identify patients with suspected and confirmed epidural hematomas. Costs for imaging to exclude or confirm the diagnosis were related to the entire cohort.
RESULTS: In our analysis, during a 9-year period that included 43,200 epidural catheterizations, 102 patients (1/430) underwent further imaging studies to exclude or confirm the presence of an epidural hematoma-revealing 6 confirmed cases and an overall incidence (per 10,000 epidural blocks) of epidural hematoma of 1.38 (95% confidence interval, 0-0.002). Among our patients, 207 imaging studies, primarily lumbar spine magnetic resonance imaging, were performed. Integrating Medicare cost expenditure data, the estimated additional cost during a 9-year period for imaging and hospital charges related to identifying epidural hematomas nets to approximately $232,000 or an additional $5.37 per epidural.
CONCLUSIONS: Approximately 1 in 430 patients undergoing epidural catheterization will be suspected to have an epidural hematoma. The cost of excluding the diagnosis, when suspected, is relatively low when allocated across all patients undergoing epidural catheterization.