Necrotizing fasciitis is a rare but severe bacterial infection that spreads rapidly through the body’s soft tissues, including the fascia, which surrounds muscles and organs. This infection can cause tissue destruction and lead to life-threatening complications. To aid medical professionals in the early assessment of suspected cases, the Laboratory Risk Indicator for Necrotizing Fasciitis (LRINEC) score, often referred to as the NECFASC score, was developed as a scoring system. This tool helps identify patients with this rapidly progressing infection, guiding timely intervention.
Understanding Necrotizing Fasciitis
Necrotizing fasciitis, sometimes called “flesh-eating disease,” swiftly destroys soft tissues and fascia. Quick diagnosis is necessary to prevent severe outcomes like organ failure, limb loss, or death.
The infection typically enters the body through a break in the skin, such as a cut, scrape, or surgical wound. Common bacterial culprits include Group A Streptococcus, also known as “flesh-eating bacteria.” Other bacteria like Klebsiella, Clostridium, Escherichia coli, and certain water-based bacteria such as Vibrio vulnificus can also be involved.
Early symptoms can be subtle and resemble the flu, including fever, chills, body aches, nausea, and diarrhea. A distinguishing symptom is intense pain at the site of injury that seems disproportionate to visible skin changes. As the infection progresses, the affected skin may become red, swollen, and warm, rapidly developing blisters, discolored areas, or a crackling sensation under the skin from bacterial gas production.
The NECFASC Score Explained
The LRINEC score, also known as the NECFASC score, is a diagnostic tool that helps distinguish necrotizing fasciitis from other soft tissue infections. This scoring system relies on six common laboratory values from a patient’s blood work upon admission. Each parameter is assigned points based on its value, reflecting the likelihood of necrotizing fasciitis.
The components of the NECFASC score include C-reactive protein (CRP), white blood cell count (WBC), hemoglobin, sodium, creatinine, and glucose. For instance, a CRP level greater than or equal to 150 mg/L is assigned 4 points. The white blood cell count contributes points based on its elevation: less than 15 x 10^3/mm^3 earns 0 points, 15 to 25 x 10^3/mm^3 earns 1 point, and greater than 25 x 10^3/mm^3 earns 2 points.
Hemoglobin levels also factor into the score; a value greater than 13.5 g/dL yields 0 points, between 11 and 13.5 g/dL yields 1 point, and less than 11 g/dL yields 2 points. Low sodium levels, specifically less than 135 mmol/L, add 2 points to the total score. Elevated creatinine, greater than 1.6 mg/dL (or 141 µmol/L), also adds 2 points. Finally, a glucose level exceeding 180 mg/dL (or 10 mmol/L) contributes 1 point.
Interpreting the Score
The total NECFASC score indicates the patient’s risk category for necrotizing fasciitis. A score of 5 or less suggests a low risk. However, approximately 10% of patients with necrotizing fasciitis may still have a score below 6.
An intermediate risk category is a score of 6 or 7, suggesting necrotizing fasciitis should be considered for further evaluation. A score of 8 or greater indicates a high risk of necrotizing fasciitis. A higher NECFASC score suggests an increased likelihood of the infection, guiding urgent diagnostic steps and potential surgical intervention.
Importance of Clinical Assessment
While the NECFASC score serves as a valuable adjunct, it is not a definitive diagnostic tool on its own. The diagnosis of necrotizing fasciitis remains primarily clinical, relying heavily on a thorough patient history and physical examination findings. Visible signs like hemorrhagic bullae, crepitus (a crackling sensation), or skin discoloration are often late manifestations, making early clinical suspicion challenging.
Medical professionals integrate the score with their observations, considering the patient’s overall clinical picture, including the severity and rapid progression of symptoms. Imaging studies, such as computed tomography (CT) scans, can also provide supporting data when the diagnosis is uncertain, helping to identify soft tissue changes. The NECFASC score is best used as an aid in decision-making, helping to stratify risk and prompt appropriate, timely management.