Injury severity score (ISS)

ISS body regions

There are only six ISS body regions to which injuries can be assigned, although the AIS 2005 - Update 2008 dictionary is divided into nine anatomical chapters.¹¹

The following may assist with assigning the body regions.

Head or neck injuries – include injury to the brain or cervical spine, skull or cervical spine fractures and asphyxia and/or suffocation.

Facial injuries – include those involving mouth, ears, nose and facial bones.

Chest injuries – include all lesions to internal organs, drowning and inhalation injury. Chest injuries also include those to the diaphragm, rib cage, and thoracic spine.

Abdominal or pelvic contents injuries – include all lesions to internal organs and lumbar spine.

Extremities or pelvic girdle injuries – include sprains, fractures, dislocations and amputations.

External and other trauma injuries – include lacerations, contusions, abrasions and burns, independent of their location on the body surface, except amputation burns that are assigned to the appropriate body region. Other traumatic events assigned to this ISS body region are: electrical injury, frostbite, hypothermia and whole body (explosion-type) injury.

ISS scoring rules

The ISS is the sum of the squares of the highest AIS code in each of the three most severely injured ISS body regions. ISS ranges from 1 to 75. If an injury is assigned an AIS of 6 (identifying a currently untreatable injury), the ISS score is automatically assigned 75.

Table 1: Example ISS calculation