From the Guidelines
Laboratory tests that can help diagnose necrotizing fasciitis include elevated white blood cell count, elevated C-reactive protein, elevated creatine kinase, low sodium levels, elevated blood glucose, and elevated blood urea nitrogen and creatinine indicating kidney dysfunction, as supported by the most recent study 1. The diagnosis of necrotizing fasciitis is primarily clinical, but laboratory tests can be helpful in supporting the diagnosis.
- Elevated white blood cell count (typically >15,000 cells/mm³) is a common finding in necrotizing fasciitis, as noted in the study by 1.
- Elevated C-reactive protein is also a useful marker, as it is often elevated in necrotizing fasciitis, as seen in the study by 1.
- Other helpful tests include coagulation studies showing abnormalities like elevated prothrombin time or partial thromboplastin time, and arterial blood gases that may reveal metabolic acidosis, as mentioned in the study by 1.
- The Laboratory Risk Indicator for Necrotizing Fasciitis (LRINEC) score uses six laboratory values (C-reactive protein, white blood cell count, hemoglobin, sodium, creatinine, and glucose) to help differentiate necrotizing fasciitis from other soft tissue infections, as described in the study by 1. However, laboratory tests alone cannot definitively diagnose necrotizing fasciitis; clinical assessment, imaging studies, and surgical exploration remain essential components of diagnosis, as emphasized in the study by 1. Some key laboratory values to consider when evaluating a patient for necrotizing fasciitis include:
- White blood cell count: typically >15,000 cells/mm³
- C-reactive protein: often elevated
- Creatine kinase: may be elevated
- Sodium: may be low (hyponatremia)
- Blood glucose: may be elevated
- Blood urea nitrogen and creatinine: may be elevated, indicating kidney dysfunction
- Hemoglobin: may be low
- Coagulation studies: may show abnormalities like elevated prothrombin time or partial thromboplastin time
- Arterial blood gases: may reveal metabolic acidosis It is essential to note that the diagnosis of necrotizing fasciitis requires a combination of clinical assessment, laboratory tests, imaging studies, and surgical exploration, as highlighted in the study by 1.
From the Research
Laboratory Findings for Necrotizing Fasciitis
The diagnosis of necrotizing fasciitis is primarily clinical, but laboratory findings and imaging studies can support the diagnosis. Some key laboratory findings include:
- Elevated white blood cell count
- Elevated creatinine and blood urea nitrogen levels
- Low serum sodium levels
- Elevated liver enzymes
- Coagulation abnormalities
Imaging Studies for Necrotizing Fasciitis
Imaging studies can help confirm the diagnosis of necrotizing fasciitis and evaluate the extent of tissue involvement. The following imaging modalities can be used:
- Radiography: may show soft tissue air or gas in the fascia 2
- Ultrasound: may show thickening of the fascia and soft tissue air, but is not recommended in adults due to limited penetration 3, 4
- Computed Tomography (CT): can show thickening of the fascia, soft tissue air, and inflammatory changes 3, 2
- Magnetic Resonance Imaging (MRI): is the gold standard imaging modality for evaluating necrotizing fasciitis, and can show thickening of the fascia, soft tissue air, and inflammatory changes 3, 4, 2
Diagnostic Scores and Adjuncts
Several diagnostic scores and adjuncts have been developed to help diagnose necrotizing fasciitis, including:
- The Laboratory Risk Indicator for Necrotizing Fasciitis (LRINEC) score: a scoring system based on laboratory parameters that can help identify patients at high risk for necrotizing fasciitis 5
- Transcutaneous tissue oxygen saturation monitoring: can help identify areas of tissue hypoxia and necrosis 5
These findings and imaging studies can help support the diagnosis of necrotizing fasciitis, but should not delay surgical intervention in patients with suspected or confirmed disease 3, 6.