The American Society of Anesthesiologists (ASA) Physical Status classification system was initially created in 1941 by the American Society of Anesthetists, an organization that later became the ASA.

The purpose of the grading system is simply to evaluate the degree of a patient's "sickness" or "physical state" before selecting the anesthetic or before performing surgery. Describing patients' preoperative physical status is used for recordkeeping, for communicating between colleagues, and to create a uniform system for statistical analysis. The grading system is not intended for use as a measure to predict operative risk.

The modern classification system consists of 6 categories, as described below.

ASA Physical Status (PS) Classification System*:

ASA PS Category

Preoperative Health Status

Comments, Examples

*ASA PS classifications from the American Society of Anesthesiologists

ASA PS 1

Normal healthy patient

No organic, physiologic, or psychiatric disturbance; excludes the very young and very old; healthy with good exercise tolerance

ASA PS 2

Patients with mild systemic disease

No functional limitations; has a well-controlled disease of one body system; controlled hypertension or diabetes without systemic effects, cigarette smoking without chronic obstructive pulmonary disease (COPD); mild obesity, pregnancy

ASA PS 3

Patients with severe systemic disease

Some functional limitation; has a controlled disease of more than one body system or one major system; no immediate danger of death; controlled congestive heart failure (CHF), stable angina, old heart attack, poorly controlled hypertension, morbid obesity, chronic renal failure; bronchospastic disease with intermittent symptoms

ASA PS 4

Patients with severe systemic disease that is a constant threat to life

Has at least one severe disease that is poorly controlled or at end stage; possible risk of death; unstable angina, symptomatic COPD, symptomatic CHF, hepatorenal failure

ASA PS 5

Moribund patients who are not expected to survive without the operation

Not expected to survive > 24 hours without surgery; imminent risk of death; multiorgan failure, sepsis syndrome with hemodynamic instability, hypothermia, poorly controlled coagulopathy

ASA PS 6

A declared brain-dead patient whose organs are being removed for donor purposes