How to identify infection in a patient with a hematoma?

Identifying Infection in a Patient with a Hematoma

Suspect infection when a patient with a hematoma develops fever, increased swelling at the site, local erythema, tenderness, or systemic signs of infection—and immediately obtain blood cultures before initiating antimicrobial therapy. 1, 2

Clinical Signs and Symptoms to Identify Infection

Local Signs at the Hematoma Site

• Increased tension or swelling at the hematoma site beyond the expected trajectory suggests infection rather than simple hematoma expansion 1, 2
• Erythema and warmth overlying the hematoma indicate inflammatory response to infection 1, 2
• Tenderness on palpation of the pocket, tunnel, or hematoma site is a key clinical indicator 1
• Purulent drainage from the site, if present, confirms infection but is not always present in deep hematomas 1

Systemic Signs

• Fever (temperature ≥38°C) developing days after hematoma formation, particularly if persistent despite initial management 1, 2, 3
• Irritability or altered mental status in patients with intracranial hematomas 2, 3
• Persistent or recurrent fever despite broad-spectrum antibiotics should raise suspicion for fungal or resistant bacterial infection 4, 5, 6

Laboratory Indicators

• Elevated C-reactive protein (CRP) levels indicate ongoing inflammation and infection 2, 3, 7
• Leukocytosis (elevated white blood cell count >10,000/mm³) suggests systemic inflammatory response 5, 3, 8
• Positive blood cultures may occur with hematogenous seeding, though they can remain sterile even with localized infection 2, 3

Diagnostic Approach

Immediate Actions

• Obtain blood cultures (both from peripheral vein and from any indwelling catheter if present) before starting antibiotics 1, 6
• Perform thorough physical examination focusing on the hematoma site, looking for the local signs described above 1
• Order inflammatory markers including complete blood count with differential, CRP, and consider procalcitonin 2, 3

Imaging Studies

• Ultrasound with high resolution (≥7.5 MHz) along the catheter or hematoma site can detect fluid collections, abscess formation, or septic thrombophlebitis 1
• CT imaging is crucial for deep hematomas (intracranial, retroperitoneal) to assess for abscess formation, increased size, or associated complications 6, 3, 7

Microbiological Sampling

• Needle aspiration of the hematoma should be avoided in cardiovascular device pockets due to risk of introducing skin flora and causing infection 1
• However, aspiration with culture is diagnostic when infection is already suspected based on clinical signs, particularly for subdural or subgaleal hematomas 2, 3, 7
• Surgical evacuation with culture is preferred over needle aspiration for definitive diagnosis and treatment 1, 7

Common Pitfalls and Caveats

Critical Timing Issues

• Hematoma evacuation should only be performed when increased tension on the skin is present, as premature intervention risks introducing infection 1
• Infected hematomas typically present 3-5 days after initial injury or procedure, not immediately 2, 3

Pathogen Considerations

• Staphylococcus aureus (including MRSA) is the most common pathogen in trauma-related infected hematomas 2, 3
• Gram-negative organisms (E. coli, Enterococcus) can seed hematomas hematogenously from distant sources like urinary tract infections 7, 8
• Streptococcus pneumoniae can infect hematomas following respiratory infections, even without scalp laceration 2
• Consider fungal infection if fever persists beyond 48-72 hours despite broad-spectrum antibiotics, particularly in immunocompromised patients 4, 5, 6

Device-Related Hematomas

• Hematoma following cardiac device implantation carries an 11-fold increased risk of major device infection in the absence of prophylactic measures 9
• Pocket infection is diagnosed by clinical signs in the subcutaneous pocket combined with bloodstream infection criteria 1

Special Populations

• Immunocompromised patients may not mount typical inflammatory responses, making clinical signs more subtle 4, 5
• Patients on anticoagulation are at higher risk for hematoma formation and should have anticoagulation held when safe to prevent expansion 1

When to Escalate Care

• Immediate surgical consultation is warranted when there is evidence of abscess formation, hemodynamic instability, or neurological deterioration 6, 7
• Broaden antimicrobial coverage to include resistant gram-positive, gram-negative, and anaerobic bacteria if the patient is hemodynamically unstable 6
• Add empiric antifungal therapy if fever persists beyond 48-72 hours on appropriate antibacterial therapy 4, 5, 6