Necrotizing fasciitis laboratory findings
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Yamuna Kondapally, M.B.B.S[2]
Overview
Laboratory findings consistent with the diagnosis of necrotizing fasciitis include positive blood and tissue culture, elevated inflammatory markers, leucocytosis and elevated serum creatinine. LRINEC is a diagnostic scoring system used to distinguish necrotizing fasciitis from other soft tissue infections.
Laboratory Findings
Laboratory tests consistent with diagnosis of necrotizing fasciitis include:[1]
Microbiology
The following are the tests used to diagnose the causative organism:
- Gram stain and culture of tissues and aspirates
- Blood culture
- Culture of throat and vaginal swabs
- Fungal culture (immunocompromised or trauma patients)
- Enrichment cultures (patients with recent antibiotic use)
Boichemistry
The biochemistry findings consistent with diagnosis of necrotizing fasciitis include:
- Elevated C-reactive protein
- Elevated serum creatine kinase
- Hypocalcemia (sign of severity in synergistic NF)
- Hypoalbuminemia
- Hyponatremia (<135mmol/L)
- Elevated serum lactate levels (high serum lactate combined with low sodium levels may be predictive of mortality)
- Arterial blood gas (ABG) analysis
- Urine analysis
- Elevated Blood urea nitrogen (BUN)
Hematology
The following are complete blood count with differential findings:
- Rapidly falling hemoglobin
- Leucocytosis (>14,000/µL)
- Leucopenia (if associated with STSS)
- Lymphopenia
- Thrombocytopenia
Laboratory risk indicator for necrotizing fasciitis (LRINEC) scoring system
- LRINEC is a diagnostic scoring system used to distinguish necrotizing fasciitis from other soft tissue infections.[2]
- It was first established by Wong et al in 2004.
- Risk assessment of necrotizing faciitis using LRINEC score:
- Low risk: ≤5
- Intermediate risk: 6-7
- High risk: ≥8
| Variable | Score |
|---|---|
| C reactive protein (mg/dL)
<150 |
0 |
| Total white blood cell count (/mm3)
<15 |
0 |
| Hemoglobin (g/dL)
<13.5 |
0 |
| Sodium (mmol/L)
≥135 |
0 |
| Creatinine (μmol/L)
<141 |
0 |
| Glucose (mmol/L)
<10 |
0 |
Tissue oxygen saturation
Other diagnostic studies of necrotizing fasciitis include:[3]
- Tissue oxygen saturation monitoring:
- It is a bed side test.
- It is a noninvasive method to continuously monitor extremities at risk and avoid delayed diagnosis.
- Tissue oxygen saturation is measured using near-infrared spectroscopy.
- In patients with necrotizing faciitis, oxygen saturation are often diminished in the lower extremities and return to normal after fasciotomy.
References
- ↑ Puvanendran R, Huey JC, Pasupathy S (2009). "Necrotizing fasciitis". Can Fam Physician. 55 (10): 981–7. PMC 2762295. PMID 19826154.
- ↑ Wong CH, Khin LW, Heng KS, Tan KC, Low CO (2004). "The LRINEC (Laboratory Risk Indicator for Necrotizing Fasciitis) score: a tool for distinguishing necrotizing fasciitis from other soft tissue infections". Crit Care Med. 32 (7): 1535–41. PMID 15241098.
- ↑ Wang TL, Hung CR (2004). "Role of tissue oxygen saturation monitoring in diagnosing necrotizing fasciitis of the lower limbs". Ann Emerg Med. 44 (3): 222–8. doi:10.1016/S0196064404003038. PMID 15332062.