Skin abscess


  • Localized collection of pus surrounded by inflamed tissue, usually caused by bacterial infection
  • MRSA is the most common cause of purulent skin and soft-tissue infections.[1][2][3]
  • Standard skin abscess are not typically due to spider bites and should not be diagnosed as such


  • Furuncles (i.e. boils) are skin abscesses caused by staphylococcal infection, which involve a hair follicle and surrounding tissue
  • Carbuncles are clusters of furuncles connected subcutaneously, causing deeper suppuration and scarring.

Clinical Features

Fluctulance on exam
  • Tender nodular region with surrounding induration
  • Fluctuance with or without surrounding erythema

Differential Diagnosis

  • Duct ectasia
  • Cyst
  • Vascular malformation

Skin and Soft Tissue Infection



Abscess on ultrasound


  • Labs
    • Not usually indicated
    • Glucose may help identify undiagnosed diabetes, if suspected
    • For febrile or systemically ill patients, obtain blood cultures, lactate, renal function, and CK
  • Imaging
    • Soft tissue ultrasound can differentiate between abscess and cellulitis
      • Assess for fluid collection and swirl within the collection
      • Recent small studies have shown limited utility to bedside ultrasound in this capacity as it rarely leads to change in management (i.e. when a provider feels there is an abscess present, ultrasound shows an abscess and when there is diagnostic uncertainty the ultrasound usually is unequivocal as well)[4]



  • Incision and drainage
  • Packing
    • Abscess >5 cm in diameter
    • Pilonidal abscess
    • Abscess in an immunocompromised or diabetic patient
  • Alternative to packing is loop drainage technique with vessel ties[5], Penrose Drain, or you can cut the proximal cuff of a sterile glove[6]
    • Failure rate of 4.1% for loop vessel technique vs 9.8% for conventional packing. [7]
    • Other advantage is don’t have to keep coming back to the ER for painful repacking.
    • Home Care[8]
      • Keep area clean.
      • Can cover with gauze to absorb the residual drainage.
      • Can shower and/or bathe.
    • The loop drain can be removed when:[9]
      • Drainage has stopped.
      • Cellulitis has improved.
      • Usually is within 7-10 days.
  • Antibiotics
    • Although withholding antibiotics is part of Choosing wisely ACEP, new evidence suggest antibiotic NNT of 14 to prevent 1 treatment failure[10]
    • TMP/SMX DS BID x 5 days[11]
    • Consider more aggressive antibiotic treatment if concomitant cellulitis



  • Reserved for significantly ill patients or those requiring surgical intervention


  • Appropriate for majority of patients
    • Follow up in 2 days for wound check

See Also

External Links


  1. Maligner D et al. The prevalence of community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) in skin abscesses presenting to the pediatric emergency department. N C Med J. 2008 Sep-Oct;69(5):351-4.
  2. Pickett A et al. Changing incidence of methicillin-resistant staphylococcus aureus skin abscesses in a pediatric emergency department. Pediatr Emerg Care. 2009 Dec;25(12):831-4.
  3. Bradley W. Frazee et al. High Prevalence of Methicillin-Resistant Staphylococcus aureus in Emergency Department Skin and Soft Tissue Infections
  4. Effect of initial bedside ultrasonography on emergency department skin and soft tissue infection management Mower WR, Crisp JG, Krishnadasan A, et al. Ann Emerg Med. 2019;74(3):372-380.
  5. Incision and Loop Drainage of Abscess BY SEAN M. FOX Pediatric EM Morsels
  6. Sterile Glove Used As a Drain for a Skin Abscess? SinaiEM
  7. Am J Emerg Med, 2018. Comparison of the loop technique with incision and drainage for soft tissue abscesses: A systematic review and meta-analysis.
  8. Incision and Loop Drainage of Abscess BY SEAN M. FOX Pediatric EM Morsels
  9. Incision and Loop Drainage of Abscess BY SEAN M. FOX Pediatric EM Morsels
  10. Talan DA, et al. Trimethoprim–Sulfamethoxazole versus placebo for uncomplicated skin abscess. NEJM. 2016; 374(9):823-832.
  11. EBQ:TMP-SMX vs Placebo for Uncomplicated Skin Abscess
  12. Daum RS, Miller LG, Immergluck L, et al. A Placebo-Controlled Trial of Antibiotics for Smaller Skin Abscesses. N Engl J Med. 2017;376(26):2545-2555. doi:10.1056/NEJMoa1607033