What is the best course of treatment for a patient with a traumatic forearm injury who develops an erythematous, swollen, fluctuant lesion, possibly an abscess?

Management of Traumatic Forearm Abscess

Incision and drainage (I&D) is the definitive treatment for this fluctuant abscess, and antibiotics should only be added if the patient demonstrates systemic signs of infection (SIRS criteria). 1

Primary Treatment: Incision and Drainage

The most important therapy for any cutaneous abscess is incision and drainage—this is non-negotiable. 1, 2 The physical findings you describe (erythematous, swollen, fluctuant lesion following trauma) are classic for an abscess requiring drainage.

Key Technical Points:

• Thoroughly evacuate all pus and probe the cavity to break up loculations 2
• For larger abscesses (>5 cm), use multiple counter-incisions rather than one long incision to prevent step-off deformity and delayed healing 2
• Simply cover with a dry sterile dressing—packing may cause more pain without improving healing 1

Decision Algorithm for Antibiotics

Antibiotics are NOT routinely needed after adequate drainage. 1 The decision hinges entirely on whether systemic inflammatory response syndrome (SIRS) is present:

NO Antibiotics Needed If:

• Temperature <38.5°C 1, 2
• Heart rate <100 beats/min 1
• White blood cell count <12,000 cells/µL 1, 2
• Minimal surrounding erythema (<5 cm) 1

ADD Antibiotics If ANY of These SIRS Criteria Present:

• Temperature >38°C or <36°C 1
• Tachycardia >90 beats/min 1
• Tachypnea >24 breaths/min 1
• WBC >12,000 or <4,000 cells/µL 1

Antibiotic Selection for Forearm Trauma:

Since this involves penetrating trauma to the forearm, empiric coverage should target both S. aureus (including MRSA) and streptococci. 1 Consider:

• Vancomycin or another anti-MRSA agent (daptomycin, linezolid) if SIRS is present 1
• Duration: 5-7 days based on clinical response 2

Critical Pitfalls to Avoid

• Do NOT attempt needle aspiration—this has only a 25% success rate overall and <10% with MRSA 1, 2
• Do NOT give antibiotics without adequate drainage—studies show no benefit when drainage is incomplete 1
• Do NOT assume antibiotics alone will work—the primary pathology is a collection requiring mechanical evacuation 1
• Forearm location warrants attention to deeper structures—ensure no involvement of deeper compartments or foreign bodies from the trauma 2

Culture Considerations

Obtain Gram stain and culture of the pus if you proceed with I&D, though treatment without these studies is reasonable in typical cases. 1 This is particularly important given:

• The traumatic etiology (possible foreign material or unusual organisms) 1
• Rising prevalence of community-acquired MRSA 1

Follow-up

• Re-evaluate at 7 days—if signs of infection persist beyond this timeframe, diagnostic re-evaluation is warranted 2
• Patients with ongoing fever or failure to improve indicate inadequate source control requiring repeat imaging or intervention 2