Necrotizing fasciitis laboratory findings: Difference between revisions
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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.
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.