AAST injury scoring scales

Last revised by Henry Knipe on 14 Feb 2024

The American Association for the Surgery of Trauma (AAST) injury scoring scales are the most widely accepted and used system of classifying and categorizing traumatic injuries. Injury grade reflects severity, guides management, and aids in prognosis. 32 different injury scores are available (c. 2019).


The most commonly used injury scoring grades are for the solid viscera: 

Injury is classified according to either imaging, operative, or pathologic criteria - the highest classification is assigned the final AAST grade 2. Grading of spleen, liver, and kidney injuries has been validated, with increasing grades of injury correlating with increasing mortality, operative rate, and hospitalization cost 3

Other scales are less commonly used, including:

  • cervical vascular injury

  • chest wall

  • heart 

  • lung 

  • thoracic vascular injury

  • diaphragm 

  • extrahepatic biliary tree 

  • esophagus 

  • stomach 

  • small bowel 

  • colon 

  • rectum 

  • abdominal vascular injury

  • ureter 

  • bladder 

  • urethra 

  • uterus

    • pregnant

    • non-pregnant 

  • fallopian tube 

  • ovary 

  • vagina 

  • vulva 

  • testis 

  • scrotum 

  • penis 

  • peripheral vascular organ injury

History and etymology

Early efforts to create an organized system for describing and grading traumatic organ injuries included 4:

  • Abbreviated Injury Scale - developed in 1971 in collaboration with the automotive industry to improve vehicle safety, as well as the

  • Injury Severity Score - developed in 1974, first to predict survival

  • Abdominal Trauma Index - developed in 1981, updated for blunt trauma in 1990, organ-specific injury grading, estimating morbidity/mortality

In the late 1980s, the American Association for the Surgery of Trauma (AAST) formed an Organ Injury Scale (OIS) committee including trauma, orthopedic surgery, urology, and neurosurgery specialists in order to create a more comprehensive classification. The first AAST OIS guidelines published in 1989 classified injuries of the spleen, liver, and kidney 5.

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