Management of Fluctuant Forearm Mass Following Minor Injury
Incision and drainage (I&D) is the most appropriate initial management for a fluctuant mass on the forearm following minor injury, as this represents an abscess requiring immediate drainage rather than systemic antibiotics alone. 1, 2
Initial Diagnostic Approach
Before proceeding with drainage, obtain plain radiographs of the forearm to exclude:
- Underlying fracture or bone involvement 3
- Radio-opaque foreign bodies 4
- Gas in soft tissues suggesting necrotizing infection 3
Radiographs serve as the foundational imaging study and can identify complications in 62% of soft tissue masses, though they may be less rewarding for small, non-mineralized superficial lesions 3
Definitive Management: Incision and Drainage
The presence of fluctuance indicates a collection of purulent material that requires mechanical drainage—antibiotics alone are insufficient. 1, 2
Drainage Technique Options
Two evidence-based approaches exist:
- Traditional I&D: Make an adequate incision, break up loculations, irrigate the cavity, and pack loosely 1
- Loop drainage: Thread a vessel loop or Penrose drain through the abscess cavity via two small incisions—this technique shows comparable or superior outcomes with fewer complications (9.3% vs 24.6%) and fewer return ED visits (37.3% vs 67.1%) 2
Both techniques achieve similar abscess resolution rates (81.5% for traditional I&D vs 88% for loop drainage at 14 days), making either approach acceptable 2
Role of Antibiotics
IV antibiotics are not the primary treatment for a simple fluctuant abscess. Drainage is the definitive intervention. 1, 2
Consider adding antibiotics only if:
- Surrounding cellulitis extends >2 cm from the abscess margin
- Systemic signs of infection (fever, tachycardia)
- Immunocompromised state
- Failed drainage or recurrence 1
Critical Pitfalls to Avoid
Do not rely on antibiotics alone for a fluctuant collection—this represents a surgical problem requiring mechanical drainage. 1, 2
Obtain radiographs before drainage to exclude underlying fracture, foreign body, or bone involvement that would change management. 3, 4
Consider atypical infections in patients with:
- Exposure to aquatic environments
- Multiple minor cuts/abrasions
- Immunocompromised status
- Recurrent or persistent masses despite adequate drainage 5
Send tissue for culture including mycobacterial studies if clinical suspicion exists for atypical organisms like Mycobacterium kansasii, which can present as chronic tenosynovitis with fluctuant masses. 5
Follow-up Considerations
Wound healing rates are similar whether using primary closure (69.6%) or secondary intention healing (59.3%) after drainage, though most simple abscesses are left open. 1
Reevaluate at 7-14 days for complete resolution, with overall failure rates around 30% requiring additional intervention. 1, 2