Version July 2025
INTRODUCTION —
Preoperative testing should be performed selectively rather than as a matter of routine. This topic will discuss the rationale for preoperative testing that may be indicated based on the patient’s medical status or the planned procedure, the timing of laboratory testing, and the appropriate use of commonly ordered tests.
Evaluation of cardiac risk prior to noncardiac surgery and preoperative testing prior to cardiac surgery are also discussed separately. (See "Evaluation of cardiac risk prior to noncardiac surgery" and "Overview of preoperative evaluation and management for cardiac surgery in adults", section on 'Preoperative testing'.)
A general discussion of preoperative evaluation for noncardiac surgery is provided separately. (See "Preoperative evaluation for noncardiac surgery in adults".)
SELECTIVE TESTING —
Selective testing refers to performing tests based on the patient's medical status (eg, unstable signs or symptoms, comorbid conditions), the planned procedure, and the likelihood that test results will change perioperative management or help with risk assessment.
Some patients who present for preoperative assessment may have previously undiagnosed, or non-optimally managed medical conditions, which may place them at increased risk for perioperative complications. Clinicians conducting the preoperative assessment, in consultation with the patient’s primary care provider, if possible, should determine whether these conditions require further management prior to the upcoming procedure. In these situations, certain tests may be indicated (table 1), particularly for patients undergoing intermediate or high-risk surgery.
Healthy patients — In healthy individuals with none of the listed problems in table 1, the prevalence of unrecognized disease that influences surgical risk is low. We agree with multiple international organizations that recommend against routine preoperative laboratory testing in the absence of clinical indication [1-4]. Multiple studies have found that preoperative testing without a clear indication does not influence perioperative management, and is not predictive of adverse surgical outcomes [5-12]. False positive results can lead to further testing, additional cost, and delay of surgery. The value of routine preoperative laboratory testing in patients undergoing low-risk surgery is particularly low among the American Society of Anesthesiologists (ASA) class 1 and 2 patients (table 2) [13].
Patients with known or suspected conditions — In general, preoperative testing for patients with known medical conditions is unnecessary for patients with stable disease. Targeted preoperative testing is indicated for patients with new or worsening signs or symptoms or potentially progressive or unstable diseases. Our recommendations for basic testing and for testing that may be considered for patients with suspected conditions who will undergo intermediate- to high-risk procedures are shown in tables (table 1 and table 3). Testing may not have added value for patients undergoing low-risk procedures and do not benefit patients having cataract surgery (table 4) [5-12,14].
Type of procedure — Recommendations for testing are based in part on the risk of the planned procedure (table 4), as well as the type of planned surgery and whether the procedure is urgent or an emergency. (See "Preoperative evaluation for noncardiac surgery in adults", section on 'Surgical risk'.)
●For most low-risk procedures, no testing is indicated unless the patient has a new, unstable, or worsening condition.
●For intermediate- or high-risk surgeries, testing is indicated based on patient comorbidities when the results will change management or risk assessment. There is no consensus on the specifics of routine testing in older patients. It is reasonable to measure hemoglobin (Hg), albumin, and creatinine preoperatively for patients >65 years of age who undergo intermediate or high risk surgery because of the relatively high incidence of anemia, malnutrition, and renal dysfunction in these patients [15]. (See "Preoperative evaluation for noncardiac surgery in adults", section on 'Older age'.)
Criteria for other preoperative laboratory testing, electrocardiogram (ECG), and chest radiograph should be based on comorbidities, rather than on age alone [15].
●Testing is also based on the type of surgery (eg, expected blood loss or the use of contrast dye).
●Emergency procedures are associated with at least twice the perioperative risk of non-emergency procedures. Recommended tests are limited due to time constraints.
TIMING OF LABORATORY TESTING —
When preoperative laboratory tests are felt to be necessary, testing should be performed with enough time before surgery to potentially correct abnormalities or perform further evaluation if necessary.
For patients who have had prior testing, the time at which it is necessary to repeat testing in anticipation of surgery is unclear, based on observational studies. It is reasonable to rely upon test results found to be normal within the previous four months unless there has been an interim change in a patient's clinical status since the previous tests. We repeat tests that were found to be abnormal, if it is felt that the results will change management.
This approach is supported by an observational study of preoperative laboratory testing in over 1100 patients undergoing elective surgery [16]. Almost half of the tests had been performed within the previous year; of previously normal tests, only 0.4 percent of preoperative tests were outside the range of normal, and most abnormal tests were predicted by a change in clinical history. Other studies have not necessarily supported this approach, but issues with study design limit their applicability [17].
LABORATORY TESTS —
Preoperative laboratory tests that may be indicated for specific patients or those undergoing specific procedures are shown in tables (table 1 and table 3). (See "Preoperative evaluation for noncardiac surgery in adults", section on 'Assessment for conditions that increase perioperative risk'.)
Commonly ordered tests — Like other preoperative tests, the following tests should be ordered selectively.
●Hemoglobin – Preoperative hemoglobin measurement should be performed for patients undergoing surgery expected to result in significant blood loss and/or with known anemia or conditions associated with anemia. One contributor to this topic routinely measures hemoglobin in patients >65 years of age who undergo major surgery because of the high incidence of anemia in older surgical patients.
The prevalence of anemia in surgical patients older than 65 can vary widely. The reported prevalences of anemia in various populations of older adults are as follows:
•Healthy community-dwelling – ≤10 percent [18].
•Nursing home residents – 48 percent [19].
•At the time of elective cardiac surgery – 40 percent of men [20].
•At the time of emergency hip fracture surgery – 46 percent [20].
•Spine surgery – 27 percent mild anemia, 2.5 percent moderate or severe anemia [21].
Preoperative hemoglobin measurement is not necessary for patients undergoing minor surgery unless the history suggests anemia. The test should ideally be performed at least four weeks before elective surgery to allow time for treatment. (See "Preoperative evaluation for noncardiac surgery in adults", section on 'Older age' and "Perioperative blood management: Strategies to minimize transfusions", section on 'Selective laboratory testing'.)
●Platelet count – Preoperative platelet count is indicated only by patient history and/or evidence of a coagulation disorder, even in patients who are having neuraxial anesthesia. (See "Overview of neuraxial anesthesia", section on 'Laboratory evaluation' and "Adverse effects of neuraxial analgesia and anesthesia for obstetrics", section on 'Neuraxial analgesia and low platelets'.)
●Creatinine – We obtain a serum creatinine in patients with known kidney disease. In addition, we obtain a creatinine in the following patients without known kidney disease:
•Patients ≥65 years of age undergoing intermediate- or high-risk surgery
•Patients who will receive nephrotoxic intravenous contrast dye
•Others based on history or comorbidities.
The prevalence of chronic kidney disease (CKD) increases with age, is often asymptomatic, and is a risk factor for perioperative morbidity and mortality. CKD may also affect management, as it may require adjustment of doses of some medications commonly used perioperatively (eg, some opioids, antibiotics, and neuromuscular blocking agents). (See "Preoperative evaluation for noncardiac surgery in adults", section on 'Kidney disease'.)
●Electrolytes – Electrolyte determinations should be obtained for patients with kidney disease or a history that increased the likelihood of an abnormality (eg, patients taking diuretics, angiotensin-converting enzyme [ACE] inhibitors, or angiotensin receptor blockers [ARBs]). In healthy adults, unexpected electrolyte abnormalities are very rare [6], and the effect of abnormalities on perioperative risk is unclear. Other indications for measuring electrolytes appear in a table (table 1).
●Blood glucose – Blood glucose should not routinely be measured in healthy patients without risk factors for hyperglycemia (eg, diabetes mellitus, severe obesity, taking glucocorticoids) (table 1). Unexpected abnormal blood glucose does not often influence perioperative management in healthy patients [22]. Preoperative testing for blood glucose and glycated hemoglobin (A1C) in patients with diabetes or hyperglycemia is discussed separately. (See "Anesthesia for patients with diabetes mellitus and/or hyperglycemia", section on 'Laboratory evaluation'.)
●Liver function tests – Liver function tests should not routinely be performed preoperatively in healthy patients (table 1). Abnormalities are uncommon and rarely change perioperative management [9,23]. Preoperative evaluation, including preoperative laboratory evaluation, and assessment of perioperative risk in patients with liver disease, are discussed separately. (See "Anesthesia for the patient with liver disease", section on 'Preoperative evaluation for patients with known liver disease' and "Assessing surgical risk in patients with liver disease", section on 'Screening for liver disease before surgery'.)
●Tests of hemostasis – Preoperative coagulation studies (ie, PT/INR, aPTT) are not indicated for patients without underlying liver disease, not taking warfarin, or without a suspicion of a bleeding disorder (table 1). This is discussed separately. (See "Preoperative assessment of bleeding risk", section on 'Laboratory testing' and "Approach to the adult with a suspected bleeding disorder".)
●Urinalysis – Routine urinalysis is not indicated preoperatively for patients without urinary symptoms before most surgical procedures, including joint arthroplasty. The theoretical reason to obtain a preoperative urinalysis is the detection of unsuspected urinary tract infection. However, screening urinalysis has not been shown to reduce infections. This is discussed in detail separately. (See "Asymptomatic bacteriuria in adults", section on 'Patients undergoing nonurologic surgery'.)
Blood type and screen and cross match
●Type and screen
•Indications – A blood type and screen is ordered whenever there is an anticipated need for a blood transfusion [24]. Patients with known red blood cell (RBC) antibodies or with an elevated risk due to a history of transfusions or pregnancy should have a type and screen performed ahead of the day of surgery if there is even a moderate risk of bleeding. Significant or multiple RBC antibodies can present difficulties with finding compatible blood.
•Timing – Type and screen must be performed within three days of transfusion for patients who have been pregnant in the previous three months (or are currently pregnant), who have received a transfusion in the past three months, or in whom the pregnancy status or transfusion history is unknown. Otherwise, a type and screen is good indefinitely per US Food and Drug Administration (FDA) rules, though most institutions set their own expiration dates.
Patients who have been transfused or pregnant at any time are at risk of having red cell antibodies, which can pose challenges for the availability of compatible cross-matched blood [24]. Information from a type and screen before the day of surgery can allow the blood bank adequate time to obtain blood. (See "Pretransfusion testing for red blood cell transfusion", section on 'Specimen requirements'.)
●Cross match
•Indications – Blood type and cross match should be based on the expectation of blood loss.
•Timing – Most crossmatching is now electronic (as long as no RBC antibodies are present) and can be done within a matter of minutes. A type and cross match always expires within three days.
Pregnancy testing — Pregnancy testing on the day of surgery should be offered to patients capable of pregnancy (table 3). Patients should have the right to refuse testing after a discussion of the potential risks associated with anesthesia, surgery, and pregnancy.
Pregnancy is excluded before gynecologic surgery in patients of reproductive age, either by the use of a screening checklist (table 5) or by pregnancy testing. (See "Gynecologic surgery: Overview of preoperative evaluation and preparation", section on 'Pregnancy test'.)
Routine preoperative pregnancy testing is controversial. Guidelines in the United Kingdom [25,26] and from the American Society of Anesthesiologists (ASA) [1] recommend offering pregnancy testing to patients in whom pregnancy is possible, but some institutions go further and require pregnancy testing for all reproductive age patients with an intact uterus before anesthesia. We offer pregnancy testing to all patients who could be pregnant, after a discussion of the potential risks associated with anesthesia, surgery, and pregnancy, but give them the option to refuse testing.
Patients who could be pregnant should understand that pregnancy may change perioperative management. The patient might elect to cancel elective surgery or choose an alternative treatment approach. In addition, anesthetic technique may be changed, and there may be risks to the fetus if a pregnancy is undetected before surgery and anesthesia. (See "Anesthesia for nonobstetric surgery during pregnancy", section on 'Effects of anesthetics on the fetus and the pregnancy'.)
Testing ahead of the day of surgery should be performed if pregnancy is suspected. However, routine screening for pregnancy is best done on the day of the surgery. (See "Gynecologic surgery: Overview of preoperative evaluation and preparation", section on 'Pregnancy test'.)
CARDIAC TESTING
Biomarkers — Plasma biomarkers (ie, brain natriuretic peptide [BNP], N-terminal pro-BNP [NT-proBNP], troponin) may be used as part of preoperative risk assessment, particularly for major adverse cardiac events. This is discussed in detail separately. (See "Evaluation of cardiac risk prior to noncardiac surgery", section on 'Subjective assessment'.)
Stress testing — Stress testing is rarely useful when performed solely because of surgery, without other indications. Although there is a clear relationship between the degree of myocardial ischemia found on testing and prognosis, there is no evidence that prophylactic revascularization only to prevent ischemia at the time of surgery improves outcomes. In addition, stress testing can lead to further invasive procedures with attendant risks (eg, cardiac catheterization, percutaneous intervention, revascularization, radiation exposure, and delay of surgery), without proven benefit. (See "Evaluation of cardiac risk prior to noncardiac surgery".)
Preoperative cardiac evaluation and testing may differ for patients being evaluated for liver or kidney transplant. (See "Kidney transplantation in adults: Evaluation of the potential kidney transplant recipient", section on 'Coronary artery disease' and "Liver transplantation in adults: Patient selection and pretransplantation evaluation", section on 'Cardiopulmonary evaluation'.)
Patients who present preoperatively with unevaluated symptoms consistent with ischemia may meet criteria for evaluation with stress testing [27]. In this case, the urgency of surgery factors into the decision on the type of testing performed. (See "Selecting the optimal cardiac stress test".)
The details of a preoperative positive stress test are as important as simply the fact that it shows ischemia, especially for patients with an established diagnosis of coronary artery disease (CAD). Large areas of stress-induced wall motion abnormalities on dobutamine stress echocardiography or stress-induced reversible perfusion defects on myocardial perfusion imaging, or poor exercise capacity on cardiopulmonary exercise testing (CPET) predict elevated risk [28,29], whereas fixed defects on myocardial perfusion scans do not predict increased risk [30].
Echocardiogram — A resting echocardiogram is warranted in patients with previously undiagnosed murmurs and symptoms of dyspnea, chest pain, syncope or near-syncope, those with undiagnosed murmurs and an abnormal electrocardiogram (ECG), heart failure with worsened symptoms, suspected hypertrophic cardiomyopathy, and for murmurs in individuals >50 years of age. (See "Preoperative evaluation for noncardiac surgery in adults", section on 'Cardiovascular disease' and "Evaluation of cardiac risk prior to noncardiac surgery" and "Perioperative management of heart failure in patients undergoing noncardiac surgery", section on 'Initial tests' and "Hypertrophic cardiomyopathy: Clinical manifestations, diagnosis, and evaluation", section on 'Echocardiography'.)
ELECTROCARDIOGRAM —
Preoperative electrocardiograms (ECGs) rarely alter perioperative management. We approach preoperative ECGs as follows:
●We do not order a preoperative ECG in a healthy patient without signs or symptoms of cardiac disease, regardless of the type of surgery.
●In general, we only obtain an ECG in patients suspected of arrhythmias or reporting palpitations, tachycardias, syncope, near syncope, new onset chest pain, or worsening angina. Other potential specific indications for preoperative ECGs appear in a table (table 1).
CHEST RADIOGRAPHS —
Preoperative chest radiographs are not indicated in adults without symptoms of pulmonary disease, or a change in baseline symptoms in patients with known cardiopulmonary disease, before any type of surgery.
Preoperative chest radiographs add little to the clinical evaluation in identifying patients at risk for perioperative complications [31]. Abnormal findings on chest radiographs occur frequently and are more prevalent in older patients [32]. There is little evidence to support the use of preoperative chest radiographs, regardless of age, unless there is known or suspected cardiopulmonary disease from the history or physical examination [33-35]. (See "Evaluation of perioperative pulmonary risk", section on 'Chest radiographs'.)
This approach is consistent with guidance from the American Society of Anesthesiologists and other advisory organizations [1,36-39].
PULMONARY FUNCTION TESTS —
Routine pulmonary function tests are not indicated for healthy patients before nonpulmonary surgery. (See "Evaluation of perioperative pulmonary risk", section on 'Pulmonary function testing'.)
These tests generally should be reserved for patients who have dyspnea, poor exercise tolerance, or a cough that remains unexplained after careful clinical evaluation, particularly in the presence of risk factors for postoperative pulmonary complications. Clinical findings (eg, decreased breath sounds, prolonged expiratory phase, rales, rhonchi, wheezes) are more predictive of the risk of postoperative pulmonary complications than are spirometric results [40]. The role of preoperative pulmonary function tests is reviewed in detail elsewhere. (See "Evaluation of perioperative pulmonary risk", section on 'Pulmonary function testing'.)
SOCIETY GUIDELINE LINKS —
Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Preoperative medical evaluation and risk assessment".)
SUMMARY AND RECOMMENDATIONS
●Selective testing – Preoperative testing should be performed selectively, based on the patient's medical status, the planned procedure, and the likelihood that test results will change management or help with risk assessment (table 6). (See 'Selective testing' above.)
●Timing of testing – Testing should be performed with enough time before surgery to potentially correct abnormalities or perform further evaluation if necessary. (See 'Timing of laboratory testing' above.)
●Commonly ordered laboratory tests – All laboratory tests should be ordered selectively. Most are not indicated for healthy patients (table 1 and table 3). Indications for commonly ordered tests are as follows: (See 'Commonly ordered tests' above.)
•Hemoglobin – Known anemia or conditions associated with anemia, or undergoing surgery associated with significant blood loss
•Platelet count – History or evidence of a coagulation disorder
•Creatinine – >65 years of age undergoing intermediate- or high-risk surgery; will receive nephrotoxic intravenous (IV) contrast; others based on history or comorbidities
•Electrolytes – Kidney disease; medications that can cause electrolyte abnormalities (eg, diuretics, angiotensin converting enzyme inhibitors, angiotensin receptor blockers)
•Blood glucose – Diabetes mellitus; severe obesity; taking glucocorticoids
•Liver function tests – Some patients with liver disease. (See "Anesthesia for the patient with liver disease", section on 'Liver function tests'.)
•Tests of hemostasis (ie, prothrombin time/international normalized ratio [PT/INR], activated thromboplastin time [aPTT]) – Liver disease; taking warfarin; suspected bleeding disorder
•Urinalysis – Symptoms of urinary tract infection
●Cardiac testing
•Electrocardiogram (ECG) – We do not order preoperative ECGs in healthy patients without signs or symptoms of cardiac disease who are having any type of surgery. We usually only obtain ECGs in patients suspected of arrhythmias or reporting palpitations, tachycardias, syncope, near syncope, new onset chest pain, or worsening angina (table 1). (See 'Electrocardiogram' above.)
•Stress test – Stress testing is rarely useful when performed solely because of surgery, without other indications. Patients who present preoperatively with unevaluated symptoms consistent with ischemia may meet criteria for evaluation with stress testing, depending on the urgency of surgery. (See "Evaluation of cardiac risk prior to noncardiac surgery" and 'Stress testing' above.)
•Echocardiogram – A resting echocardiogram is warranted in patients with undiagnosed murmurs and symptoms of dyspnea, chest pain, syncope, or near-syncope, those with undiagnosed murmurs and an abnormal ECG, and for murmurs in individuals >50 years of age. (See "Preoperative evaluation for noncardiac surgery in adults", section on 'Cardiovascular disease' and 'Echocardiogram' above.)
•Biomarkers – Plasma biomarkers (ie, brain natriuretic peptide [BNP], N-terminal pro-BNP [NT-proBNP], troponin) may be used as part of preoperative risk assessment, particularly for major adverse cardiac events. (See 'Biomarkers' above and "Evaluation of cardiac risk prior to noncardiac surgery", section on 'Subjective assessment'.)
●Chest radiograph – Preoperative chest radiographs are not indicated in adults without symptoms of pulmonary disease, or a change in baseline symptoms in patients with known cardiopulmonary disease, before any type of surgery. (See 'Chest radiographs' above and "Evaluation of perioperative pulmonary risk", section on 'Chest radiographs'.)
●Pulmonary function tests – These tests should not be performed routinely in patients before nonpulmonary surgery. In most cases, clinical findings of pulmonary disease are more predictive of postoperative pulmonary complications than are spirometric results. (See 'Pulmonary function tests' above and "Evaluation of perioperative pulmonary risk", section on 'Pulmonary function testing'.)
