Preoperative Assessment and Risk Stratification

Preoperative assessment and risk stratification is the systematic evaluation of a patient before anesthesia and surgery, undertaken to characterize baseline health, identify conditions that raise perioperative risk, and estimate the probability of adverse outcomes. It links the patient's history, examination, and selected investigations to validated risk indices so that the anesthetic and surgical plan can be matched to the individual.

Definition

Preoperative assessment is the clinical process of evaluating a patient's fitness for anesthesia and surgery, and risk stratification is the assignment of that patient to a category of expected perioperative risk using history, examination, investigations, and validated indices.

Scope

This area covers the components and logic of the preoperative evaluation: structured history-taking and physical examination, the ASA physical status classification, organ-system risk assessment (notably cardiovascular and pulmonary), and preoperative preparation such as fasting and premedication. It is organized as a reference orientation; the detailed essentials live in the topic nodes beneath it.

Sub-topics

• ASA Physical Status Classification
• Cardiovascular Risk Assessment
• Fasting Guidelines and Premedication
• Patient History and Physical Examination
• Pulmonary Risk Assessment

Core questions

• What baseline conditions does the patient have that could affect anesthesia or surgery?
• How is overall perioperative risk classified and communicated?
• Which organ-system risks (cardiac, pulmonary) most influence outcome for this procedure?
• What preoperative preparation reduces avoidable harm?

Key concepts

• Baseline health characterization
• ASA physical status classification
• Functional capacity
• Organ-system risk assessment
• Validated risk indices
• Procedure-specific surgical risk
• Shared communication of risk

Mechanisms

Risk stratification proceeds from data to a structured estimate: the history and physical examination identify comorbidities and functional limitations, targeted investigations refine uncertain findings, and validated tools translate these into a category or score. The ASA physical status classification provides a global descriptor of systemic disease, while organ-specific indices such as the Revised Cardiac Risk Index estimate the probability of defined complications for major noncardiac surgery (Lee, 1999). Combining patient factors with the inherent risk of the planned procedure yields the perioperative risk estimate that informs planning.

Clinical relevance

Preoperative assessment is the entry point of perioperative care and the basis on which anesthetic and surgical teams plan, allocate monitoring, and counsel patients about risk. As a reference area it explains how perioperative risk is conceptualized and estimated; it describes the structure of evaluation rather than prescribing individual management.

Epidemiology

Postoperative complications, including cardiac and pulmonary events, are a recognized source of perioperative morbidity and mortality, and structured assessment aims to identify the patients at highest risk. Cardiovascular and pulmonary complications are among the most studied adverse outcomes, and large cohorts and systematic reviews underpin the indices used to estimate them (Lee, 1999; Smetana, 2006).

History

Structured preoperative grading dates to Saklad's 1941 scheme for classifying patients before surgery, which evolved into the modern ASA physical status classification. Over subsequent decades, organ-specific risk prediction matured with cardiac risk indices and pulmonary risk reviews, and professional bodies consolidated the evidence into perioperative evaluation guidelines (Fleisher, 2014; Smetana, 2006).

Key figures

• Meyer Saklad
• Lee A. Fleisher
• Thomas H. Lee
• Gerald W. Smetana

Seminal works

• lee-1999
• smetana-2006
• fleisher-2014

Frequently asked questions

What is the purpose of preoperative assessment?

To characterize a patient's baseline health, identify conditions that raise perioperative risk, and estimate the probability of adverse outcomes so that the anesthetic and surgical plan can be matched to the individual.

Is risk stratification the same as the ASA classification?

No. The ASA physical status classification is one widely used global descriptor of systemic disease, but risk stratification also draws on organ-specific indices, functional capacity, and the inherent risk of the planned procedure.