Ultrasound Detection of Soft Tissue Abscesses Performed by Non-Physician U.S. Army Medical Providers Naïve to Diagnostic Sonography

Abstract

Background: Patients commonly present to emergency rooms and primary care clinics with cellulitic skin infections with or without abscess formation. In military operational units, non-physician medical personnel provide most primary and initial emergency medical care. The objective of this study was to determine if, after minimal training, Army physician assistants and medics could use portable ultrasound (US) machines to detect superficial soft tissue abscesses.

Methods: This was a single-blinded, randomized, prospective observational study conducted over the course of 2 days at a military installation. Active duty military physician assistants and medics with little or no US experience were recruited as participants. They received a short block of training on abscess detection using both clinical examination skills (inspection/palpation) and US examination. The participants were then asked to provide a yes/no answer regarding abscess presence in a chicken tissue model. Results were analyzed to assess the participants' abilities to detect abscesses, compare the diagnostic accuracy of their clinical examinations with their US examinations, and assess how often US results changed treatment plans initially on the basis of clinical examination findings alone.

Results: 22 participants performed a total of 220 clinical examinations and 220 US scans on 10 chicken tissue abscess models. Clinical examination for abscess detection yielded a sensitivity of 73.5% (95% confidence interval [CI], 65.3-80.3%) and a specificity of 77.2% (95% CI, 67.4-84.9%), although US examination for abscess detection yielded a sensitivity of 99.2% (95% CI, 95.4-99.9%) and a specificity of 95.5% (95% CI, 88.5-98.6%). Clinical examination yielded a diagnostic accuracy of 75.0% (95% CI, 68.9-80.3) although US examination yielded a diagnostic accuracy of 97.7% (95% CI, 94.6-99.2%), a difference in accuracy of 22.7% favoring US (p < 0.01). US changed the diagnosis in 56 of 220 cases (25.4% of all cases, p = 0.02). Of these 56 cases, US led to the correct diagnosis 53 of 56 times (94.6%).

Conclusion: Non-physician military medical providers can be trained in a very brief period to use US to detect superficial soft tissue abscesses with excellent accuracy.