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New Injury Severity Score (NISS)
Advanced Anatomical Scoring
Top 3 AIS Scores overall (0-6)
Head & Neck
Face
Chest / Thorax
Abdomen / Pelvis
Extremities
External / Skin
Select AIS Values
Input the Abbreviated Injury Scale (AIS) scores to calculate the New Injury Severity Score (NISS).
Guidelines & Evidence
Verified
Last Review: 2026
When to Use
The New Injury Severity Score (NISS) is an anatomical scoring system that modifies the traditional Injury Severity Score (ISS). While the ISS only considers the single most severe injury per body region, the NISS sums the squares of the three most severe injuries regardless of anatomical region. This makes it particularly effective for capturing the true severity of "clustered" injuries, such as multiple penetrating wounds to the chest or complex blunt abdominal trauma.
Feature
Injury Severity Score (ISS)
New Injury Severity Score (NISS)
Region Limitation
Max 1 injury per region
No region limitation
Clustered Injuries
Underestimates severity
Captures full severity
Calculation
Sum of squares (3 regions)
Sum of squares (3 top injuries)
Sensitivity
Lower in penetrating trauma
Higher in penetrating trauma
Complexity
Moderate (requires region coding)
Lower (simple top-3 approach)
The NISS is always ≥ ISS for any given patient. If a patient has their three most severe injuries in three different regions, the NISS and ISS will be identical.
Related Scores in Practice
In clinical practice, this assessment is frequently evaluated alongside other validated measures. Depending on the patient's presentation and specific diagnostic requirements, you may also need to utilize the Iss Score, Triss Index, Ais Score, or the Tash Score to formulate a comprehensive care plan.
