No tests? When?

In many instances, a surgeon has already ordered preop testing by the time a medical physician performs preoperative evaluation. In some instances, you may have discretion to order the testing of your choice. When might you choose no preop testing whatsoever? 

Numerous studies and organizations have noted the low (or worse) value of preop testing in certain situations. The American Society of Anesthesia (ASA) guideline of 2012 stated, "Preoperative tests should not be ordered routinely. Preoperative tests may be ordered, required, or performed on a selective basis for purposes of guiding or optimizing perioperative management." They continued, "The indications for such testing should be documented and based on information obtained from medical records, patient interview, physical examination, and type and invasiveness of the planned procedure." 

ASA continued in 2013 with their first of five contributions to the Choosing Wisely Campaign: "Don’t obtain baseline laboratory studies in patients without significant systemic disease (ASA class I or II) undergoing low-risk surgery – specifically complete blood count, basic or comprehensive metabolic panel, coagulation studies when blood loss (or fluid shifts) is/are expected to be minimal." They left room for discretion in individual cases, consistent with their 2012 advice to order tests based upon specific concerns rather than routinely. 

Subsequently there has been much research supporting the move away from preop testing in those with ASA Physical Status class I and II. Two recent large retrospective cohort studies from the American College of Surgeons (ACS) National Surgical Quality Improvement Program (NSQIP) evaluated overlapping cohorts of hundreds of thousands of patients undergoing low-risk outpatient procedures, finding much testing and no statistically significant benefit to testing (Vikas, J Clin Anes 2022, Taylor, Anes 2022). RCT's remain lacking. 

To consider deimplementing preop testing as recommended, you must know the ASA physical status class system and the definition of low-risk surgery.

ⓘ ASA Physical Status Classes

Here are the details of the ASA class system (from Horvath, Anesth 2021).

ASA Physical Status Classification System 
I A normal healthy patient 
II A patient with mild systemic disease 
III A patient with severe systemic disease 
IV A patient with severe systemic disease that is a constant threat to life
 V A moribund patient who is not expected to survive without the operation 
VI A declared brain-dead patient whose organs are being removed for donor purposes 

These definitions, by themselves, would be vague without further detail. Since the issue here is to distinguish Class II patients who may not need preop testing from Class III and IV who do need testing, note the further details of II, III, and IV. 

I A normal healthy patient. Details, examples: Healthy, nonsmoking, no or minimal alcohol use.

II A patient with mild systemic disease. Details, examples: Mild diseases only without substantive functional limitations. Current smoker, social alcohol drinker, pregnancy, obesity (30 < BMI < 40), well-controlled diabetes and/or HTN, mild lung disease. 

III A patient with severe systemic disease. Details, examples: Substantive functional limitations; one or more moderate to severe diseases. Poorly controlled diabetes or HTN, COPD, morbid obesity (BMI ≥ 40), active hepatitis, alcohol dependence or abuse, implanted pacemaker, moderate reduced EF, ESRD undergoing regularly scheduled dialysis, history (> 3 months) of MI, stroke, TIA, or CAD/stents. 

IV A patient with severe systemic disease that is a constant threat to life. Details, examples: Recent (< 3 months) MI, stroke, TIA, or CAD/stents, ongoing cardiac ischemia or severe valve dysfunction, severe reduced of EF, shock, sepsis, DIC, ARDS, or ESRD not undergoing regularly scheduled dialysis. 

V A moribund patient who is not expected to survive without the operation. Details, examples: Ruptured abdominal/thoracic aneurysm, massive trauma, intracranial bleed with mass effect, ischemic bowel in the face of significant cardiac pathology or multiple organ/system dysfunction. 

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

ⓘ surgical risk levels

Low-risk surgery was defined in each ACC-AHA preop guideline through 2007, not appearing in 2014 and 2024. Risk categories are based upon combined cardiac risk of morbidity and mortality. 

Low-risk: <1% cardiac morbidity & mortality even in high risk patients. 
Examples: 
- endoscopic procedure 
- superficial procedure 
- cataract surgery 
- breast surgery 
- ambulatory surgery 

Intermediate-risk: 1-5% cardiac morbidity & mortality. 
Examples: 
- intra-peritoneal/thoracic surgery 
- carotid endarterectomy 
- head and neck surgery 
- orthopedic, prostate surgery 

High-risk: >5% cardiac morbidity & mortality. 
Examples: 
- aortic & other major vessel surgery 
- peripheral vascular surgery

Refs abbrev: Practice Advisory for Preanesthesia Evaluaton, etc. Anesth 2012; 116:522–38. Choosing Wisely, American Society of Anesthesiologists, Oct. 2013. Others as noted above.