Abscess Aspiration

Overview

Incision and drainage (I\&D) is the standard guideline treatment of uncomplicated skin abscesses (a boil or bumo beneath the skin). Ultrasound-guided needle aspiration (USGNA) is a minimally invasive and less painful alternative treatment, but has not been validated as non-inferior to I\&D. Multiple studies have shown successful treatment with USGNA of breast, face, neck, and/or trunk abscesses in combination with oral antibiotics with success rates as high as 97%. In 2011 Gaspari et al. published a landmark article on the use of USGNA for skin abscesses. In this randomized controlled trial, USGNA and I\&D had failure rates of 74% and 20% respectively, which makes USGNA an unappealing treatment option. However, the study had several methodological issues that likely biased the results in favor of I\&D, including the following: 1) aspiration was performed with an 18-gauge needle which is often too small to aspirate thick purulence (or pus); 2) failure to fully aspirate all abscess contents was a priori defined as treatment failure rather than strictly clinical outcomes; 3) the abscess aspiration procedure was not standardized; and 4) post-intervention oral antibiotic therapy was not used on all patients. The main hypothesis is that a modified protocol of the Gaspari et al. USGNA study to address these flaws will demonstrate a failure of USGNA comparable to I\&D for the treatment of uncomplicated skin abscesses. First, the study will standardize the use of larger 14-gauge needle on all USGNAs. Second, USGNA intervention failure need not be defined as the inability to completely aspirate all abscess cavity contents under ultrasound guidance. Previous studies have demonstrated clinical success with USGNA of skin abscesses without applying the rigid failure criteria chosen by Gaspari et al. There is only one study in the literature to suggest that there is no correlation between a small quantity of residual abscess contents post-USGNA and ultimate clinical failure, however, there are no studies which specifically address this clinical question. In this study, initial treatment failure of USGNA will be defined as the inability to aspirate any purulent material. Third, treatment outcomes in this study will be determined by clinical resolution of abscess at the study endpoint of 7-10 days, which is a well-established timeline for anticipated abscess healing and endpoint clinical follow-up. Fourth, ultrasound fellowship-trained emergency physicians will perform USGNA in standardized fashion on all enrolled patients. Lastly, post-intervention oral antibiotic with methicillin-resistant Staphylococcus aureus (MRSA) coverage will be provided and compliance closely monitored throughout the study.