Serial white blood cell counts in trauma: do they predict a hollow viscus injury?

BACKGROUND: The significance of serial white blood cell (WBC) counts in trauma patients with a suspected hollow viscus injury (HVI) is unknown. The purpose of this study was to examine the role of serial WBC counts in the diagnosis of a HVI.

METHODS: After institutional review board approval, all injured patients admitted to a Level I trauma center from January 2003 to December 2007 with at least one WBC measurement were included in a retrospective analysis. The WBC profiles for patients with a HVI were compared against those without HVI. All WBC counts are reported as [x10(3)/microL].

RESULTS: The mean WBC count of the overall study population (n = 5,950) on admission was 11.6 +/- 5.3. Overall, 59.2% had an elevated WBC count on admission. A significant relationship between increasing Injury Severity Score and increasing WBC count on admission was found by linear regression. When comparing patients with HVI (n = 267) with patients without HVI (n = 5,683), no significant difference was found for admission WBC count. The highest WBC count within the first 24 hours for patients with HVI was 16.7 +/- 4.7. This was significantly higher than that for the 4,520 patients without any intraabdominal injury (13.0 +/- 5.2, adjusted p < 0.001). Penetrating injury, a concomitant severe thoracic trauma (chest Abbreviated Injury Scale value >or=3), and highest WBC count >or=20.0 in the first 24 hours were independent risk factors for HVI. A maximal WBC count <or=12.5 in the first 24 hours was independently associated with a lower incidence of HVI. The area under the receiver operating characteristic curve for the highest WBC count in the first 24 hours for predicting HVI was 0.723 (95% CI: 0.656-0.790).

CONCLUSION: Multiple variables likely impact the WBC count in trauma patients. WBC count elevation on admission is nonspecific and does not predict the presence of a HVI. With serial measurements, WBC counts >or=20.0 are independently associated with a HVI, whereas counts <or=12.5 rule against the presence of HVI. However, the sensitivity of these cutoff values to predict a HVI is poor. The diagnostic value of serial WBC counts for predicting a HVI within the first 24 hours after trauma is very limited.