To determine the test characteristics of point-of-care ultrasonography for the identification of a drainable abscess and to compare the test characteristics of ultrasonography with physical examination. In addition, we sought to measure the extent to which ultrasonography impacts clinical management of children with skin and soft tissue infections (SSTIs).Study design
We performed a prospective study of children with SSTIs evaluated in a pediatric emergency department. Treating physicians recorded their initial impression of whether a drainable abscess was present based on physical examination. Another physician, blinded to the treating physician's assessment, performed an ultrasound study and conveyed their interpretation and recommendations to the treating physician. Any management change was recorded. An abscess was defined as a lesion from which purulent fluid was expressed during a drainage procedure in the emergency department or during the 2- to 5-day follow-up period. We defined a change in management as correct when the ultrasound diagnosis was discordant from physical examination and matched the ultimate lesion classification.Results
Of 151 SSTIs evaluated among 148 patients, the sensitivity and specificity of point-of-care ultrasonography for the presence of abscess were 96% (95% CI 90%-99%) and 87% (74%-95%), respectively. The sensitivity and specificity of physical examination for the presence of abscess were 84% (75%-90%) and 60% (44%-73%), respectively. For every 4 ultrasound examinations performed, there was 1 correct change in management.Conclusions
Point-of-care ultrasonography demonstrates excellent test characteristics for the identification of skin abscess and has superior test characteristics compared with physical examination alone.