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

Background: In military operational units, non-physician medical personnel provide the bulk of primary and initial emergency medical care. Patients with skin and soft tissue infections (SSTI) commonly present to emergency... [ view full abstract ]

Background: In military operational units, non-physician medical personnel provide the bulk of primary and initial emergency medical care. Patients with skin and soft tissue infections (SSTI) commonly present to emergency rooms and primary care clinics and physical exam is unreliable in identifying the presence of abscess in the setting of SSTI. The objective of this study was to determine if, after minimal training, Army physician assistants (PAs) and medics could use portable ultrasound (US) machines to accurately detect superficial soft tissue abscesses.

Methods: This was a single-blinded, randomized, prospective observational study conducted over the course of two days at a military installation. Active duty military PAs 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 exam skills (inspection/palpation) and US exam. 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 exams with their US exams, and assess how often US results changed treatment plans initially based on clinical exam findings alone.

Results: 22 participants performed a total of 220 clinical exams and 220 US scans on ten chicken tissue abscess models. Clinical exam for abscess detection yielded a sensitivity of 73.5% (95% CI, 65.3%-80.3%) and a specificity of 77.2% (95% CI, 67.4%-84.9%), while US exam 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 exam yielded a diagnostic accuracy of 75.0% (95% CI, 68.9%-80.3) while US exam 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 of time to use US to detect superficial soft tissue abscesses with excellent accuracy.