ABSCESS: applied bedside sonography for convenient evaluation of superficial soft tissue infections.

OBJECTIVES

Soft tissue infections are a common presenting complaint in the emergency department (ED). The authors sought to determine the utility of ED bedside ultrasonography (US) in detecting subcutaneous abscesses.

METHODS

Between August 2003 and November 2004, a prospective, convenience sample of adult patients with a chief complaint suggestive of cellulitis and/or abscess was enrolled. US was performed by attending physicians or residents who had attended a 30-minute training session in soft tissue US. The treating physician recorded a yes/no assessment of whether he or she believed an abscess was present before and after the US examination. Incision and drainage (I + D) was the criterion standard when performed, while resolution on seven-day follow-up was the criterion standard when I + D was not performed.

RESULTS

Sixty-four of 107 patients had I + D-proven abscess, 17 of 107 had negative I + D, and 26 of 107 improved with antibiotic therapy alone. The sensitivity of clinical examination for abscesses was 86% (95% confidence interval [CI] = 76% to 93%), and the specificity was 70% (95% CI = 55% to 82%). The positive predictive value was 81% (95% CI = 70% to 90%), and the negative predictive value was 77% (95% CI = 62% to 88%). The sensitivity of US for abscess was 98% (95% CI = 93% to 100%), and the specificity was 88% (95% CI = 76% to 96%). The positive predictive value was 93% (95% CI = 84% to 97%), and the negative predictive value was 97% (95% CI = 88% to 100%). Of 18 cases in which US disagreed with the clinical examination, US was correct in 17 (94% of cases with disagreement, chi(2) = 14.2, p = 0.0002).

CONCLUSIONS

ED bedside US improves accuracy in detection of superficial abscesses.