AAST Bladder Injury Scale AAST Bowel Injury Scale AAST Cardiac Injury Scale AAST Diaphragm Injury Scale AAST Hepatic Injury Scale AAST Kidney Injury Scale AAST Lung Injury Scale AAST Pancreatic Injury Scale AAST Rectal Injury Scale AAST Splenic Injury Scale AAST Vascular Injury Scale ABC Score (Massive Transfusion)ACS COT Field Triage Guidelines ATLS Hemorrhagic Shock Classification Abbreviated Injury Scale (AIS)Ankle-Brachial Index (ABI) in Trauma Base Deficit in Trauma Brain Injury Guidelines (BIG) Score Cardiac Wound Index Chest Trauma Score (CTS)Damage Control Decision Score (DCDS)Denver Criteria (BCVI)Esophageal Perforation Severity Score (PSS)Expanded Denver Criteria (BCVI)Flint Colon Injury Scale Frailty Index in Trauma (mFI-5)Geriatric Trauma Outcome Score (GTOS)Hard Signs of Vascular Injury Checklist Hemorrhage Control Decision Aid (Wound Packing vs. Tourniquet)ICP-based Cerebral Perfusion Pressure (CPP) Calculator Injury Severity Score (ISS)Injury Severity Score — Age-adjusted (ISS-Age)Lethal Triad / Trauma Triad of Death Calculator Limb Salvage Index (LSI)Mangled Extremity Severity Score (MESS)Mechanism, Glasgow Coma Scale, Age, and Arterial Pressure (MGAP)Memphis Criteria (BCVI)Modified Shock Index (MSI)Nerve Injury, Ischemia, Soft-tissue, Skeletal Injury, Shock, Age (NISSSA)New Injury Severity Score (NISS)Open Abdomen Classification (Björck)Pediatric Trauma Score (PTS)Pelvic Trauma Hemorrhage Risk Score Penetrating Abdominal Trauma Index (PATI)Physiologic Extreme Emergency in Trauma (FEET)Predictive Salvage Index (PSI)REBOA Zone Selection Guide Resuscitative Thoracotomy Indications (EAST/WTA Guidelines)Revised Trauma Score (RTS)RibScore Shock Index (SI)TASH Score TRISS Index Thoracic Trauma Severity Score (TTS)Tile Classification of Pelvic Fractures Trauma and Injury Severity Score — Pediatric (PTS)Young–Burgess Pelvic Fracture Classification

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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.

Last Comprehensive Review: 2026

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