Accuracy of Physical Exam, Ankle-Brachial Index, and Ultrasonography in the Diagnosis of Arterial Injury in Patients with Penetrating Extremity Trauma: A Systematic Review and Meta-Analysis

Abstract

Background

Penetrating Extremity Trauma (PET) may result in arterial injury, a rare but limb- and life-threatening surgical emergency. Accurate and timely diagnosis is vital to enable potential intervention and prevent significant morbidity.

Objectives

Using a systematic review/meta-analysis approach, we determined the utility of Physical Examination (exam), Ankle-Brachial Index (ABI), and Ultrasonography (US) in the diagnosis of arterial injury in ED patients who have sustained PET. We applied a test-treatment threshold model to determine which evaluations may obviate CT Angiography (CTA).

Methods

We searched PUBMED, EMBASE, and SCOPUS from inception to November 2016 for studies of ED patients with PET. We included studies on adult and pediatric subjects presenting to the ED with PET. We defined the reference standard to include CTA, catheter angiography, or surgical exploration. When low-risk patients did not undergo the reference standard, trials must have specified that patients were observed for at least 24 hours. We used the Quality Assessment Tool for Diagnostic Accuracy Studies (QUADAS-2) to evaluate bias and applicability of the included studies. We calculated positive and negative Likelihood Ratios (LR+ and LR-) of exam ("hard" signs of vascular injury), US, and ABI. Using established CTA test characteristics (sensitivity 96.2%, specificity 99.2%) and applying Pauker-Kassirer method, we developed a test-treatment threshold model (testing threshold: 0.14%, treatment threshold: 72.9%).

Results

We included 8 studies (n=2,161, arterial injury prevalence: 15.5%). Studies had variable quality with most at high risk for partial and double verification bias. Some studies investigated multiple index tests: Exam (hard signs) was investigated in 3 studies (n=1,170), ABI in 5 studies (n=1,040), and US in 4 studies (n=173). Due to high heterogeneity (I² >75%) of the results, we could not calculate LR+ or LR- for hard signs or LR+ for ABI. The weighted prevalence of arterial injury for ABI was 14.3% and LR- was 0.59 (95% CI 0.48-0.71) resulting in a post-test probability of 9% of arterial injury. Ultrasonography (US) had weighted prevalence of 18.9%, LR+ 35.4 (95% CI 8.3-151), and LR- 0.24 (95% CI 0.08-0.72); post-test probabilities for arterial injury were 89% and 5% after a positive or negative US, respectively. The post-test probability of arterial injury with positive US (89%) exceeded the CTA treatment-threshold (72.9%). The post-test probabilities of arterial injury with negative US (5%) and normal ABI (9%) exceeded the CTA testing-threshold (0.14%). Normal exam (no hard or soft signs) with normal ABI had a combined LR- of 0.01 (95% CI 0.0-0.10) resulting in an arterial injury post-test probability of 0%.

Conclusions

In PET patients, a positive US may obviate CTA. In patients with a normal exam (no hard or soft signs) and a normal ABI, arterial injury can be ruled out. However, a normal ABI or negative US cannot independently exclude arterial injury. Due to large study heterogeneity, we cannot make recommendations when hard signs are present or absent or when ABI is abnormal. In these situations, the physician should use clinical judgment to determine the need for further observation, CTA or catheter angiography, or surgical exploration.

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