Diagnostic value of CT contrast extravasation for major arterial injury after pelvic fracture: A meta-analysis
Introduction
Approximately one in ten blunt trauma victims admitted to level 1 trauma referral centers sustain pelvic fractures [1]. Bleeding pelvic fractures are an immediate life-threatening injury associated with significant mortality [2], [3], [4], [5], [6], [7]. Rapid hemorrhage control is associated with improved survival [2], [8], but surgical decision making remains challenging due to difficulty determining the bleeding source [2], [4], [9]. Hemorrhage can arise from arterial injury, venous injury, or fractured bone ends [2], [5], [10]. Angioembolization and external fixation are the most common treatment pathways for hemorrhage associated with pelvic fracture, with each therapy aimed at addressing different sources of bleeding [2], [3], [11]. A central decision point critical to the timely and optimal deployment of appropriate resources and initial treatment strategies hinges on whether active arterial bleeding is present [2], [3], [12].
Early aggressive trans-catheter arterial embolization (TAE) is well established as an effective means of reducing transfusion requirement, complications, and mortality from arterial hemorrhage [2], [3], [4], [13], [14], [15], [16], [17], [18], [19], whereas low pressure bleeding from the rich pelvic venous plexus or fractured bone ends is best controlled through splinting, reduction of pelvic volume, and tamponade using external fixation [2], [3], [19], [20]. Contrast enhanced CT is the cornerstone screening exam for evidence of arterial bleeding in patients with pelvic fractures who are sufficiently stable for transport to a trauma resuscitation unit CT scanner [19]. In a recent epidemiologic study spanning 11 Level 1 trauma centers, CT was used in up to 85% of patients admitted in shock [2].
The Eastern Association for the Surgery of Trauma (EAST) practice management guidelines note that research has primarily focused on two imaging signs for determining need for TAE- CE and pelvic hematoma volume [19]. The latter has been difficult to measure reliably or efficiently at the point of care using diameter-based or manual segmentation techniques [21], [22], [23]. The EAST guidelines therefore emphasize CE as the most useful imaging predictor of the need for pelvic angiography and TAE in the clinical setting and recommend that patients with CE be considered for TAE regardless of hemodynamic status [19]. A number of studies have assessed the accuracy of CE for predicting angiopositivity or hemostatic intervention with TAE [19], however published sensitivities and specificities are highly variable [11], [19], [24]. Improvements in CT scanner technology should improve detection and characterization of bleeding, but there is speculation that improved image quality and temporal resolution with 64-detector row or higher CT scanners might also confound assessment due to increased detection of small self-limiting foci of CE [5], [9], [20], [24]. Dynamic characterization of CE using multiphase image protocols is thought to improve diagnostic certainty in such cases, but there are no comparative effectiveness studies assessing the diagnostic performance benefit of multiphase over single phase protocols. Our objectives were to a) establish pooled accuracy metrics of CT for predicting angiopositivity and need for TAE despite the wide variability described in the literature, and b) determine whether diagnostic performance improves with the use of 64 detector row CT and multiphasic protocols [9], [22],
We hypothesized that 64- or higher MDCT scanners and multiphasic protocols would improve diagnostic performance. We also sought to provide more precise estimates of the diagnostic performance of CE for predicting major arterial injury (defined by positive angiographic findings and use of TAE for hemorrhage control). Several potentially confounding aspects of study design were investigated as sources of heterogeneity in the published results.
Section snippets
Materials and Methods
The protocol for this systematic review and meta-analysis was designed in consultation with an experienced biostatistician and research librarian using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines [25], and QUADAS-2 background document [26]. We determined the pooled diagnostic accuracy of contrast extravasation (CE) at admission trauma CT for correctly identifying arterial bleeding on subsequent angiography and need for TAE in patients who have
Study identification and selection
Our search initially yielded 205 unique references, of which 57 were deemed potentially relevant following review of titles and abstracts and were assessed for eligibility through detailed manual review of full text articles. 34 manuscripts that asked a different study question, had absent or incomplete accuracy data, or did not allow reconstruction of a 2 × 2 contingency table were eliminated. One article in Japanese was included after using online machine translation software (Google
Discussion
Pelvic fracture-related hemorrhage is life-threatening but potentially reversible with timely and appropriately chosen intervention [2], [45]. TAE is the most common definitive method of hemorrhage control in patients with arterial sources of bleeding, while external fixation is used to control low pressure venous or bone bleeding through splinting of sharp bone ends, reduction of pelvic volume, and tamponade [2]. In current practice, the great majority of patients with pelvic fractures undergo
Conclusion
The sensitivity of CE for angiographic evidence of bleeding and need for TAE is significantly improved with the use of 64-detector row scanners (94%). High specificity (92%) can be maintained by incorporating multiphasic scan protocols. Missed or delayed diagnosis of arterial injury and false positives resulting in unnecessary angiography will still occur with some frequency. Additional predictors of bleeding including pelvic hematoma and fracture severity should be taken into account.
CRediT authorship contribution statement
David Dreizin: Conceptualization, Investigation, Writing - original draft. Yuanyuan Liang: Investigation, Methodology. James Dent: Data curation, Investigation, Methodology. Nabeel Akhter: Investigation. Daniel Mascarenhas: Investigation. Thomas M. Scalea: Conceptualization, Writing - review & editing.
Sources of funding
1. RSNA Research Scholar Grant (#RSCH1605) (PI: David Dreizin, MD).
2. NIH National Institute of Biomedical Imaging and Bioengineering (NIBIB) K08 EB027141-01A1 (PI: David Dreizin, MD).
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