Original Contribution Serial hematocrit testing does not identify major injuries in trauma patients in an observation unit Troy Madsen MD ⁎ , Matthew Dawson MD, Joseph Bledsoe MD, Philip Bossart MD Division of Emergency Medicine, University of Utah, Salt Lake City, UT 84132, USA Received 16 December 2008; revised 26 January 2009; accepted 27 January 2009 Abstract Background: Routine serial hematocrit measurements are a component of the trauma evaluation for patients without serious injury identified on initial evaluation. We sought to determine whether serial hematocrit testing was useful in detecting significant intra-abdominal injuries in trauma patients in our observation unit. Methods: We performed a retrospective chart review of all trauma patients placed in our observation unit over a 14-month period. Patients had received trauma surgery evaluation before placement in the observation unit and routinely received serial hematocrit testing (≥2 hematocrit levels) while in the observation unit. We compared trauma patients with a hematocrit drop of 5 points or more to those without a significant hematocrit drop. Results: Three hundred sixty-five trauma patients were placed in the observation unit, and 310 patients (85%) had at least 2 hematocrits drawn during their stay. Of these patients, 20.6% had a hematocrit drop of 5 or more. Of patients with the hematocrit change, 18.8% were admitted to an inpatient unit from the observation unit compared to 9.3% of patients without a significant hematocrit change (P = .034). In one of these patients who had a computed tomography scan before observation admission, which demonstrated free fluid, the hematocrit drop assisted in diagnosing significant intra-abdominal injury. Conclusion: Although serial hematocrit testing may be useful in specific situations, routine use of serial hematocrit testing in trauma patients at a level I trauma center's observation unit did not significantly aid in the detection of occult injury. © 2010 Elsevier Inc. All rights reserved. 1. Introduction The use of serial hematocrit testing as a screening tool after the initial trauma evaluation has been suggested to aid in the diagnosis of intra-abdominal injury and may be the practice in some trauma centers [1,2]. One previous study has reported that a change in hematocrit of more than 5 points predicted serious injury. This study, however, evaluated the use of 4-hour hematocrit change to predict injuries that had already been diagnosed in the initial trauma evaluation [1]. An additional study has demonstrated that a hematocrit change of 6.5 points at 15 minutes predicts significant injury in patients with penetrating trauma [2]. These studies, however, did not look specifically at patients who had received an initial trauma evaluation and then had serial hematocrit testing as a screening tool for undiagnosed injury. The goal of our study was to determine whether routine serial hematocrit testing is useful in detecting occult serious injury in trauma patients after initial trauma evaluation. We ⁎ Corresponding author. Tel.: +1 801 581 2417; fax: +1 801 585 6699. E-mail address: troy.madsen@hsc.utah.edu (T. Madsen). www.elsevier.com/locate/ajem 0735-6757/$ – see front matter © 2010 Elsevier Inc. All rights reserved. doi:10.1016/j.ajem.2009.01.034 American Journal of Emergency Medicine (2010) 28, 472–476