What laboratory tests do you order for new wound care patients?

Laboratory Tests for New Wound Care Patients

For new wound care patients, obtain wound cultures only when infection is clinically present, along with complete blood count, comprehensive metabolic panel, and hemoglobin A1c, with additional vascular studies for suspected ischemia. 1, 2

Core Laboratory Tests

Wound Culture Specimens

• Only culture clinically infected wounds - culturing uninfected wounds is unnecessary and not recommended 1
• Proper specimen collection is critical:
  • Cleanse and debride the wound before obtaining specimens
  • Obtain tissue specimens from the debrided base via curettage or biopsy (preferred method) 1
  • Avoid swabbing undebrided ulcers or wound drainage
  • If tissue sampling isn't possible, use a swab designed for aerobic and anaerobic organisms 1
  • Clearly identify samples with specimen type and anatomic location 1

Blood Tests

• Complete Blood Count (CBC) - to assess for systemic infection and inflammatory response 1
• Blood cultures - should be performed for patients with severe infections or systemic illness 1
• Comprehensive Metabolic Panel - to evaluate renal function, electrolytes, and nutritional status
• Hemoglobin A1c - for diabetic patients to assess glycemic control 2

Additional Tests Based on Wound Assessment

Vascular Assessment

For wounds with suspected ischemia:

• Ankle-Brachial Index (ABI) - values of 0.50-0.90 indicate mild-to-moderate peripheral vascular disease; <0.50 suggests ischemia that will likely impair wound healing 1
• Toe pressure measurements - should be >30 mmHg 1, 2
• Transcutaneous oxygen measurement (TcpO2) - values <30 mmHg indicate inadequate perfusion 1

Bone Involvement Assessment

For deep or chronic wounds with suspected osteomyelitis:

• Plain radiographs - first-line imaging for bone involvement 1
• MRI - more sensitive for early osteomyelitis and provides anatomic information about sinus tracts or abscesses 1

Specialized Testing Based on Wound Type

Burn Wounds

• Quantitative tissue biopsy cultures - recommended for monitoring infection in burn wounds 1
• Histopathological examination - should supplement quantitative bacterial cultures to assess microbial invasion 1

Diabetic Foot Ulcers

• Peripheral neuropathy assessment - using 10-g Semmes-Weinstein monofilament test 1
• Probe-to-bone test - to assess for osteomyelitis (bone touched with a probe has a characteristic stony feel) 1

Common Pitfalls to Avoid

• Don't culture clinically uninfected lesions - this leads to unnecessary antibiotic use 1
• Don't use superficial swabs when tissue specimens can be obtained - swabs yield less accurate results than tissue samples 1
• Don't label specimens simply as "wound" - be specific about body site and type of wound 1
• Don't ask the laboratory to report everything that grows - this can lead to treatment of colonizing organisms rather than pathogens 1
• Don't rely solely on clinical signs for diagnosing infection in certain wounds (e.g., burn wounds) - laboratory confirmation is essential 1

By following this systematic approach to laboratory testing for new wound care patients, clinicians can accurately diagnose infections, guide appropriate antimicrobial therapy, and monitor wound healing progress while avoiding unnecessary tests and treatments.