Preoperative Testing: Which Tests to Order and When

The preoperative evaluation and testing for patients should be tailored based on their clinical condition, ongoing medication treatments, and any anomalies detected during their medical history review or physical examination. This approach is essential to assess the severity of known medical conditions and uncover any asymptomatic or hidden illnesses, which could influence the feasibility, timing, or safety of the intended surgery and associated anesthesia. This evaluation should be conducted well in advance of the surgery to allow any existing comorbidities to be adequately managed. Conditions like silent heart disease, anemia, and kidney disease may significantly affect surgical outcomes.

Interestingly, among patients with a higher American Society of Anesthesiologists (ASA) classification of III-IV, the incidence of unexpected pathological findings is minimal (0.8%). This low rate may be attributed to these patients being more rigorously monitored biochemically due to their more severe health conditions, compared to those with fewer comorbidities.

Recommendations for routine Preoperative Tests (POTs) for elective surgeries advise integrating test results from primary care into the surgical consultation process to prevent redundant testing. However, it's important to note that there's no concrete evidence showing that routine preoperative testing significantly alters postoperative outcomes. Test results from the past six months can be considered current if the patient's condition has remained stable, though more recent tests might be necessary if there have been changes in the patient's health status.

Common Preoperative Tests

A routine test is characterized as one conducted without a particular clinical reason, aimed at identifying potential diseases or disorders in patients who show no symptoms. However, preoperative tests should not be conducted as a matter of routine. Instead, they ought to be selectively requested to aid in directing or enhancing perioperative care. Broad categorizations like “preop status” or “surgical screening” do not qualify as precise clinical justifications for these tests.

On the other hand, an indicated test is one that is prescribed for a distinct clinical rationale or objective. These tests are chosen based on detailed information gathered from medical records, patient interviews, and physical examinations, as well as considerations of the procedure's type and level of invasiveness and the anesthesia to be used. This information is crucial for anesthesia providers to determine the most appropriate perioperative evaluation and management strategy.

• CBC
  • H&P findings suggestive of abnormality
    • Known cytopenia
    • Recent chemo
    • History of bleeding
    • Liver disease
    • History of anemia, bleeding, etc.
  • Anticipated large surgical blood loss
  • Major surgery
  • Chronic cardiovascular, pulmonary, renal, or hepatic disease; or malignancy
• Coagulation panel: INR and aPTT
  • Current anticoagulant therapy or baseline result for postoperative coagulation
  • Known history of a bleeding disorder or previous bleeding complications
  • History of bruising or bleeding is a better predictor of bleeding problems than laboratory testing.
  • Liver disease 
  • Before starting a peripheral nerve block or neuraxial anesthesia
• Chemistry panel (potassium, glucose, sodium, creatinine/BUN, albumin)
  • Endocrine disorders
  • Hypertension 
  • Risk of kidney or liver dysfunction
  • Patient on diuretics 
  • Hypoalbuminemia is a predictor of increased perioperative complications such as pulmonary and infectious complications 
• Specifically Potassium
  • If the patient is taking digoxin, diuretics, ACE inhibitors, or angiotensin receptor blockers
• Urinalysis: not indicated except for specific procedures such as prosthesis implantation or urological procedures
• CXR
• Pulmonary function tests
• EKG