What standard tests and labs are required for pre-surgery clearance?

Standard Preoperative Testing and Laboratory Evaluation

Preoperative testing should be guided by patient-specific risk factors rather than performed routinely, with testing reserved for patients with clinical history, comorbidities, or physical examination findings that suggest underlying disease requiring perioperative optimization. 1

Risk-Stratified Approach to Testing

Electrocardiography (ECG)

• Order ECG for patients undergoing high-risk surgery or intermediate-risk surgery with additional cardiac risk factors (coronary heart disease, structural heart disease, heart failure, cerebrovascular disease, diabetes, or renal impairment) 1
• Do not order ECG for patients undergoing low-risk surgery, even if they have stable cardiovascular disease 1
• Patients with good functional capacity (≥4 METs or ability to climb ≥2 flights of stairs) can proceed to surgery without further cardiac testing 1

Complete Blood Count (CBC)

Order CBC only when clinically indicated:

• Patients with liver disease, hematologic disorders, or history of anemia 2, 1
• History of recent blood loss 2
• Anticipated significant perioperative blood loss 1
• Cardiovascular surgery or neurosurgery 2
• ASA class 2-3 patients with cardiovascular or respiratory disease undergoing major surgery (grade 3-4) 2
• Patients older than 60 years undergoing neurosurgery 2

Electrolytes and Renal Function

Order electrolyte and creatinine testing for:

• Patients taking medications predisposing to electrolyte abnormalities (diuretics, ACE inhibitors, ARBs, NSAIDs, digoxin) 1
• Known renal disease, hypertension, heart failure, complicated diabetes, or liver disease 1
• All patients undergoing neurosurgery or cardiovascular surgery 2
• All patients older than 40 years undergoing major+ surgery (grade 4) 2
• ASA class 3 patients with cardiovascular disease 2

Glucose Testing

• Order random glucose testing only for patients at high risk of undiagnosed diabetes mellitus 1
• In patients with diagnosed diabetes, order A1C testing only if results would change perioperative management 1
• Universal screening is not justified given the low incidence (0.5%) of occult diabetes in presurgical populations 1

Coagulation Studies

Reserve coagulation testing (PT, aPTT, platelet count) for:

• History of bleeding or medical conditions predisposing to coagulopathy (e.g., liver disease) 1
• Patients taking anticoagulants 1
• Do not perform indiscriminate preoperative coagulation testing due to low prevalence of inherited coagulopathies 1

Chest Radiography

• Do not perform routine chest X-rays for asymptomatic, otherwise healthy patients 1
• Order chest radiography only for patients with new or unstable cardiopulmonary signs or symptoms 1
• Consider for patients at risk of postoperative pulmonary complications if results would change perioperative management 1

Urinalysis

• Do not perform routine urinalysis for asymptomatic patients 1
• Order urinalysis only for patients undergoing urologic procedures or implantation of foreign material (prosthetic joint, heart valve) 1

Special Populations

Healthy Patients Undergoing Low-Risk Surgery

Patients in their usual state of health undergoing cataract surgery do not require any preoperative testing 1

Patients with Moderate Renal Impairment (eGFR 45 mL/min/1.73 m²)

• Obtain CBC as patients with eGFR <60 mL/min/1.73 m² have increased risk of anemia 1
• Check serum calcium, phosphate, PTH, and alkaline phosphatase in patients with eGFR <45 mL/min/1.73 m² to assess for metabolic bone disease 1

Timing of Laboratory Testing

Laboratory tests performed up to 2 months before surgery in ASA I-II patients with normal results do not require repeat testing, as there is no increased risk of 30-day morbidity and mortality compared to testing within 1 week of surgery 3. However, testing performed 2-3 months before surgery is associated with increased odds of adverse outcomes and should prompt repeat testing 3.

Key Clinical Pitfalls

• Avoid protocol-driven testing batteries that apply the same tests to all patients regardless of clinical indication 2, 1
• Do not delay surgery for routine testing in otherwise healthy patients, as this increases costs without improving outcomes 2
• Recognize that advanced age alone is not an indication for ancillary testing; testing should be based on suspected organ disease or medication side effects 4
• Understand that normal test results rarely change perioperative management in asymptomatic patients with no clinical findings 4, 5