abscess aspiration

Conditions: Skin Abscess

Summary: 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.


Eligibility criteria:
inclusion criteria: 1. non-toxic patients who present with an uncomplicated, superficial skin abscess of the head/neck, torso, extremities, and buttock will be eligible for inclusion. 2. abscesses must be verified by physical examination and bedside ultrasound. 3. patients with clinical history of diabetes mellitus and previous diagnosis of mrsa will be included. exclusion criteria: 1. patients will be excluded if age less than age 18 or pregnant. 2. patient or legal guardian is unable to give consent. 3. patients with no means of clinical follow-up will be excluded. 4. complicated abscesses, defined as an abscess with associated sepsis, lymphangitis, or osteomyelitis, requiring intravenous antibiotic therapy, requiring hospital admission, previous surgical drainage at site of abscess, overlying skin lesion/fistula/ulceration with the exception of cellulitis, perforated or actively draining abscess, duration of symptoms \> 5 days,1,28 and/or multiple concurrent abscesses that can be clinically regarded as chronic in nature will be excluded. 4) abscess locations which will be excluded are dental, peritonsillar, anorectal, genital/inguinal, axillary if suspicion for chronic hidradenitis suppurativa, or pilonidal/intragluteal at the base of the coccyx. 5) abscesses greater in size than 3x3x3 cm in any dimension will be excluded. \[it has been suggested extensively in the surgical literature that an abscess diameter \>3 cm should have surgical/catheter-drainage as the initial management instead of needle aspiration\]2,5,15,19,27,33 \[it has been reported that abscesses \>3 cm in size have increased failure rates\]15 6) abscess depth is greater than maximal needle length. 7) patients with immunosuppression from following clinical conditions will be excluded: hiv, cancer on active chemotherapy. 8) patients with active history of iv drug use will be excluded.

Keywords: ultrasound guided needle aspiration incision and drainage