The use of whole body CT (WBCT) – or “pan scan” – in trauma is an often debated topic in the emergency department (ED). The poly-consult setting of trauma involves multiple services that rapidly evaluate and treat a patient. With improved protocols, higher resolution imaging, and closer proximity of CT scanners to the trauma room, WBCT has become a more widely used part of the trauma evaluation protocol. Support for its use increased as initial studies, albeit sub-optimally designed, showed a mortality benefit and a decreased time to multiple endpoints (1).
1. The Initial Data
Much of the initial data comes from two large, retrospective studies. The first study in 2009 by Huber-Wagner et al (2) analyzed data from 9,259 patients in the trauma registry of the German Trauma Society. They included 4,621 patients of whom 1,494 (32%) underwent WBCT, 3,127 (68%) underwent selective CT, and 697 did not have any CT. They showed that the actual mortality of patients who had WBCT scans was significantly lower than their expected mortality based on Trauma and Injury Severity Score (TRISS) and Revised Injury Severity Classification (RISC) score calculations There were no significant differences between the actual and estimated mortality in the selective CT or “no CT” group. Huber-Wagner et al concluded that WBCT conferred a mortality benefit which was lost when selective imaging or no imaging was performed.
A second study by Huber-Wagner et al in 2013 (3) used data from the same registry to look at hemodynamically unstable patients with an ISS > 16. They sought to challenge the contention that WBCT should not be performed in trauma patients in shock. 16,719 patients were included in their analysis of whom 9,233 received WBCT, 7,486 underwent selective CT, and 1,072 patients had no CT imaging. The study also looked at patient subgroups of varying ranges of hemodynamic instability: no shock (SBP > 110), moderate shock (SBP 90-110), or severe shock (SBP < 90). They found that standardized mortality ratios, which compared actual mortality to RISC score-calculated mortality, were significantly lower in the WBCT group overall, as well as in groups with various degrees of hemodynamic instability.
2. REACT-2
The REACT-2 trial (4) aimed to provide Level 1 evidence regarding the utility of WBCT in trauma. This international, multicenter RCT enrolled patients from four level 1 trauma centers. The trial excluded patients who were under the age of 18, pregnant, transferred from other hospitals and had low-energy trauma, stab wounds, or were taken directly to the OR. They used criteria that included abnormal vital signs, altered mental status, and high-energy mechanisms to enroll a severely injured population. The intervention group received a two-step CT head, neck, chest, abdomen, and pelvis without gantry angulation. The standard work-up group included initial chest and pelvis x-rays followed by FAST, and subsequently, selective CT of specific body regions.
After exclusions, 541 patients were enrolled in the WBCT group and 542 in the standard work-up group. The populations were similar except that the WBCT group had slightly more polytrauma patients and slightly lower hemoglobin/hematocrit levels. The study was adequately powered to detect a 5% mortality difference between the two groups. The in-hospital mortality in both groups was 16%. Additionally, there was no differences in mortality in polytrauma (22% in WBCT vs. 25% in standard work up) and TBI subgroups (38% in WBCT vs. 44% in standard work up). The study did show statistically significant decrease in times to completion of imaging and diagnosis of life-threatening injuries in the WBCT group compared to the standard work up. Additionally, it showed a significant increase in the median initial (20.9 vs. 20.6 mSv) and total amount of radiation (21.0 vs. 20.6 mSv) for patients undergoing WBCT versus selective CT. However, such a small difference is unlikely to have clinical relevance.
The study was well-run and attempted to replicate real practice in order to maximize external validity. However, post-hoc analysis found that the study population was not as sick as in previous trials with 36% of patients having an ISS < 16; this was the minimum score for most of the previous studies. Additionally, 250 (46%) of the standard workup patients underwent sequential CT of all body regions equivalent to a WBCT in the end. These two factors may have accounted for the lack of mortality difference seen between the study and control groups.
REACT-2 is the first large RCT to compare WBCT to selective imaging in a trauma population. The study contributed high quality data to the debate and showed physicians can use selective CT without increasing mortality.
3. Harms of the Pan-Scan
The rapid adoption of WBCT in trauma seems to have taken place without a full examination of the risks associated with this intervention. By indiscriminately ordering WBCT, patients may have more incidental findings that lead to increased anxiety, downstream testing, and costs. A recent New York trauma registry study (5) found that 40% had incidental findings on their trauma CTs. Of these, 63% were considered Class 2 findings that did not require urgent evaluation but were also not normal variants, thus requiring further work-up.
Another detrimental side effect from CT overuse is increased radiation exposure and subsequent increased risk of malignancy. This is especially concerning in trauma patients as they tend to be younger and often exposed to serial CT imaging during their hospitalization. The REACT-2 trial showed a statistically significant difference in radiation exposure between the WBCT and selective CT groups. Forty-five percent of patients in the selective CT group had a lower radiation exposure than the 20 mSv dose from a WBCT (4).
Much of the data regarding radiation exposure and cancer risk comes from cohort studies of atomic bomb survivors. The 2006 Health effects of exposure to low levels of ionizing radiation (BEIR VII) report (6) estimated that exposure to 100 mSv (approximately five WBCTs) increased the lifetime risk of cancer by 1%. This effect varies with age at exposure and may be double in children compared to adults. A study (7) has used similar data to estimate cancer risk in trauma patients, but this data showed significant heterogeneity in dose exposure related to injury severity.
Radiation exposure in high doses is clearly harmful. The data on the risks of low dose radiation comes from models and estimations based on effects at higher doses. These calculations are derived from numerous variables including the radiation dose emitted, dose absorbed, and equivalent dose based on the tissue absorbing the dose. These variables are dependent on the imaging machine, programming of the machine, and the age of the patient. Therefore, it is difficult to create a standardized model that can apply to large groups of patients (8). While the extrapolation and application of these estimates in trauma patients is theoretical and further study is needed, there is clearly some risk involved, which should be factored when possible, into the decision-making process when ordering CTs.
4. What To Do
Unfortunately, the evidence in support of WBCT is low in quality. While a systematic review (1) may show a mortality benefit associated with WBCT, it analyzse a large volume of retrospective data, which is prone to bias. Experts agree that more high-quality data is needed, but this does not help the patient in front of us. In the end, we need to be advocates for our patients in this hectic environment.
The best current data comes from REACT-2, which showed that physicians may determine which CTs are indicated without significantly impacting mortality (4). This means we can resist the “one-size-fits-all” approach that has made WBCT ubiquitous in blunt trauma. A selective imaging strategy is ideally suited for high-volume trauma centers with resources available for acute resuscitation and subsequent observation. WBCT may be higher yield in high-mechanism, obtunded, polytrauma patients who will have a greater prevalence of serious injuries, and future high-quality research may show a mortality benefit in this high-risk cohort. In the meantime, when possible, we should use thorough clinical assessment and shared decision-making to perform selective CT imaging in relatively lower risk patients.
Read more evidence based articles on trauma management for Emergency Medicine physicians.
- Surendran A, Mori A, Varma DK, Gruen RL. Systematic review of the benefits and harms of whole-body computed tomography in the early management of multitrauma patients. Journal of Trauma and Acute Care Surgery 2014;76(4):1122–30.
- Huber-Wagner S, Lefering R, Qvick L-M, et al. Effect of whole-body CT during trauma resuscitation on survival: a retrospective, multicentre study. The Lancet 2009;373(9673):1455–61.
- Huber-Wagner S, Biberthaler P, Häberle S, et al. Whole-Body CT in Haemodynamically Unstable Severely Injured Patients – A Retrospective, Multicentre Study. PLoS ONE 2013;8(7).
- Sierink JC, Treskes K, Edwards MJR, et al. Immediate total-body CT scanning versus conventional imaging and selective CT scanning in patients with severe trauma (REACT-2): a randomised controlled trial. The Lancet 2016;388(10045):673–83.
- Andrawes P, Picon AI, Shariff MA, et al. CT scan incidental findings in trauma patients: does it impact hospital length of stay? Trauma Surgery & Acute Care Open 2017;2(1):1–6.
- Committee to Assess Health Risks from Exposure to Low Levels of Ionizing Radiation (BEIR VII Phase 2) NRC. Health effects of exposure to low levels of ionizing radiation: BEIR VII. Washington (DC): National Academies Press; 2006.
- Hui CM, MacGregor JH, Tien HC, Kortbeek JB. Radiation dose from initial trauma assessment and resuscitation: review of the literature [Internet]. Canadian Journal of Surgery. 2009.
- Baron B, Scott J. Limiting Radiation Exposure in Trauma Imaging. In: Emergency Trauma Care: Current Topics And Controversies. Norcross, GA: EB Medicine; In Press.
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