Is an established medical score to assess trauma severity.
It correlates with mortality, morbidity and hospitalization time after trauma. It is used to define the term major trauma.
A major trauma (or polytrauma) is defined as the Injury Severity Score being greater than 15.
The ISS is based upon the Abbreviated Injury Scale (AIS).
To calculate an ISS for an injured person, the body is divided into six ISS body regions.
These body regions are:
Head or neck - including cervical spine
Face - including the facial skeleton, nose, mouth, eyes and ears
Chest - thoracic spine and diaphragm
Abdomen or pelvic contents - abdominal organs and lumbar spine
Extremities or pelvic girdle - pelvic skeleton
To calculate an ISS, take the highest AIS severity code in each of the three most severely injured ISS body regions, square each AIS code and add the three squared numbers for an ISS (ISS = A2 + B2 + C2 where A, B, C are the AIS scores of the three most injured ISS body regions). The ISS scores ranges from 1 to 75 (i.e. AIS scores of 5 for each category). If any of the three scores is a 6, the score is automatically set at 75. Since a score of 6 (“unsurvivable”) indicates the futility of further medical care in preserving life, this may mean a cessation of further care in triage for a patient with a score of 6 in any category.