What is the Injury Severity Score?

The injury severity score, or ISS, is a numerical value that is intended to quantify the severity of a wound or wounds. It is particularly effective for judging the condition of individuals with multiple wounds, as it takes into account six different areas of the body, including head and neck, face, and soft tissue. A value from 1 to 6 is assigned to the wounds at each part of the body, with 1 representing a minor wound and 6 representing an unsurvivable wound. The most severe wound at the three most severely injured parts of a person's body are squared and added together, generally returning scores from 1 to 75. One of the major weaknesses of the injury severity score is that is can, at times, be somewhat arbitrary as people may judge the severity of wounds differently.

If any of the wounds are given a severity value of 6, the injury severity score is immediately set to 75. A 6 will only be assigned to wounds that a medical professional judges to be unsurvivable. If there is any doubt, the wound is more likely to receive a score of 5, representing a critical injury. When multiple injured people are present, someone with injuries judged to be unsurvivable will likely be passed over as medical professionals may choose to treat more hopeful cases first. Individuals with cumulative scores below 10, on the other hand, may not require immediate treatment because their wounds are quite minor.

An individual with an injury severity score greater than 16 is said to be suffering from a polytrauma. A polytrauma is a condition in which one has sustained several physical injuries of a somewhat severe nature. Though polytrauma is a generic term, it is often used by military doctors to explain the conditions of soldiers with multiple severe wounds. It also is possible that someone who has an injury severity score above 16 may not actually have sustained multiple wounds. If this is the case, his single wound is likely to be very serious and be in need of immediate medical attention.

Imagine a person who has suffered wounds to the neck, chest, hand, and lower back. The hand wound is little more than a scratch; it is ignored as only the three most severe wounds are considered for the injury severity score. The neck is badly bruised, there is a bleeding gash on the chest, and the lower back is giving the person considerable pain, so the wounds will be given scores of 2, 3, and 2, respectively. 2 squared, plus 3 squared, plus 2 squared returns an injury severity score of 17. The individual is considered, then, to be suffering from a moderate to severe polytrauma.