Is it time to re-think FAST? A systematic review and meta-analysis of Contrast-Enhanced Ultrasound (CEUS) and conventional ultrasound for initial assessment of abdominal trauma

Abstract

Background The Focused Assessment with Sonography for Trauma (FAST) examination using conventional ultrasound has limited utility for detecting solid organ injury. Therefore, this systematic review and meta-analysis compares the performance of contrast-enhanced ultrasound (CEUS) to conventional ultrasound when used as the initial assessment for abdominal trauma prior to computed tomography (CT) imaging. Methods A systematic literature search of major databases was conducted of human studies investigating the diagnostic accuracy of conventional ultrasound and CEUS occurring prior to CT imaging for abdominal trauma. The study followed the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) statement. The quality of studies was evaluated using the QUADAS-2 (Quality Assessment of Diagnostic Accuracy Studies 2) tool. Paired pooled sensitivity and specificity between conventional ultrasound and CEUS were compared using data extracted from the eligible studies. Diagnostic odds ratio, number needed to diagnose values, and likelihood ratios were also determined. Results Ten studies were included. More than half of the included studies demonstrated low risk of bias. Using McNemar’s test to assess for paired binary observations, we found that CEUS had statistically higher sensitivity (0.933 vs. 0.559; two-tailed, P < 0.001) and specificity (0.995 vs. 0.979; two-tailed, P < 0.001) than conventional ultrasound in the setting of abdominal trauma, respectively. When divided into particular findings of clinical interest, CEUS had statistically higher sensitivity than conventional ultrasound in screening for active bleeding and injuries to all abdominal solid organs. CEUS also had superior diagnostic odds ratios, number needed to diagnose values, and likelihood ratios than conventional ultrasound. Conclusion The diagnostic value of CEUS was higher than that of conventional ultrasound for differentiating traumatic abdominal injuries when used as the initial assessment in the emergency department.

Contrast‐enhanced point of care ultrasound for the evaluation of stable blunt abdominal trauma by the emergency physician: A prospective diagnostic study

“…By combining all positive sonographic findings, the sensitivity of the examination for traumatic CT findings is much higher than CEUS alone but the specificity is limited. In our study, this low specificity is substantially explained by the presence of two patients with ascites, which contribute to the lower positive likelihood ratio compared to previously published studies 7 …”

“…It shows that CEUS has a pooled positive likelihood ratio (PLR) of 125 and pooled negative likelihood ratio (NLR) of 0.07 for traumatic findings compared to CT and a low heterogeneity. The same work shows that in previous studies CEUS has been performed by experienced radiologists or sonographers or evaluated, retrospectively 7 …”

“…Our data are thus consistent with previously published studies showing that CEUS improves the sensitivity for SOL. 6,7,21 The five injuries missed by CEUS were all lower grade (grade 1-2 AAST injuries) and treated conservatively. We would like to emphasize that two lesions reported as "suspicious" on the CT report were clinically insignificant but were still considered as positive CT findings in our analysis, and this lowers the reported CEUS sensitivity (Table 4).…”

“…Our results suggest that CEUS can be safely implemented by EPs who are trained in POCUS abdominal sonography, provided that they have experience in abdominal sonography (200 examinations) and receive at least 3 h of specific training in CEUS to achieve results concordant to those obtained by radiologists in previous studies. 6,7,21,23 In these studies, the sonographers had more than 5 years of experience in abdominal sonography or at least >300 abdominal sonographic examinations.…”

“…The integration of other diagnostic modalities (eg, hematuria screening) could decrease the posterior probability of kidney injury for which contrast sonography shows a higher NLR compared to liver and splenic injuries. 7 The EP, seeking to safely discharge his patient home, regularly has to weigh the benefits and risks of an abdominal CT. In the situation of a borderline indication to CT, he may be tempted to overly rely on a normal noncontrast US to rule out intraabdominal injury.…”