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Preoperative Evaluation


Paul K. Mohabir

, MD, Stanford University School of Medicine;

André V Coombs

, MBBS, Texas Tech University Health Sciences Center

Last full review/revision Nov 2020| Content last modified Nov 2020
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Before elective surgical procedures, whether done in an outpatient or inpatient setting, the surgical team may consult an internist for a formal preoperative evaluation to minimize risk by identifying correctable abnormalities and by determining whether additional perioperative monitoring and treatment are needed. The goal of a thorough preoperative evaluation should be to provide patients with a personalized surgical plan to minimize operative risk and postoperative complications. In some cases, elective procedures should be delayed when possible so that certain underlying disorders (eg, hypertension, diabetes, hematologic abnormalities) can be optimally controlled. In other cases, patients deemed high risk for major surgery may be identified preoperatively as candidates for less invasive interventions.

A thorough preoperative medical evaluation may require input from nonsurgical consultants (eg, internists, cardiologists, pulmonologists) to help assess surgical risk. Such consultants may also help manage preexisting disease (eg, diabetes) and help prevent and treat perioperative and postoperative complications (eg, cardiac, pulmonary, infectious). Psychiatric consultation is occasionally needed to assess capacity or help deal with underlying psychiatric problems that can interfere with recovery.

Older patients may benefit from involvement of an interdisciplinary geriatric team, which may need to involve social workers, therapists, ethicists, and other practitioners.

Because not all surgical procedures are elective, the acuity and type of proposed operation should be considered as well as the patient's risk with surgery. For example, if an emergency procedure is required (eg, for intra-abdominal hemorrhage, perforated viscus, necrotizing fasciitis), there is usually no time for a full preoperative evaluation. However, the patient's history should be reviewed as expeditiously as possible, particularly for allergies and to help identify factors that increase risk of emergency surgery (eg, history of bleeding problems or adverse anesthetic reactions).


A relevant preoperative history includes information about all of the following:

  • Current symptoms suggesting an active cardiopulmonary disorder (eg, cough, chest pain, dyspnea during exertion, ankle swelling) or infection (eg, fever, dysuria)

  • Risk factors for excessive bleeding (eg, known bleeding disorder, history of bleeding excessively with dental procedures, elective surgeries, or childbirth)

  • Risk factors for thromboembolism (see Deep Venous Thrombosis (DVT))

  • Risk factors for infection

  • Known disorders that increase risk of complications, particularly hypertension, heart disease, kidney disease, liver disease, diabetes, asthma, and COPD (chronic obstructive pulmonary disease)

  • Previous surgery, anesthesia, or both, particularly their complications

  • Allergies

  • Tobacco, alcohol, and illicit drug use

  • Current prescription and nonprescription drug and supplement use

  • History of obstructive sleep apnea or excessive snoring

If an indwelling bladder catheter may be needed, patients should be asked about prior urinary retention and prostate surgery.

Physical examination

Physical examination should address not only areas affected by the surgical procedure but also the cardiopulmonary system, as well as a search for any signs of ongoing infection (eg, upper respiratory tract, skin).

When spinal anesthesia is likely to be used, patients should be evaluated for scoliosis and other anatomic abnormalities that may complicate lumbar puncture.

Any cognitive dysfunction, especially in older patients who will be given a general anesthetic, should be noted. Preexisting dysfunction may become more apparent postoperatively and, if undetected beforehand, may be misinterpreted as a surgical complication.


Because healthy patients undergoing elective surgery have a low prevalence of silent disease that would otherwise influence perioperative management, routine preoperative testing should not be done in those without clinical symptoms or significant underlying disease. Such testing is not cost-effective and results in false-positive tests, unintended patient alarm, and delays in surgery. Preoperative testing should therefore be individualized and based on the patient's clinical presentation, although preoperative beta-hCG (human chorionic gonadotropin) pregnancy testing should be done in all women of childbearing age (1, 2, 3).

In symptomatic patients, those with known underlying disease, or those undergoing operations with a higher risk of significant bleeding or other complications, laboratory evaluation may include the following tests:

  • Complete blood count (CBC) and urinalysis (glucose, protein, and cells) usually are done. CBC is particularly relevant in patients > 65 or in younger patients with significant anticipated blood loss.

  • Serum electrolytes and creatinine and plasma glucose are measured unless patients are extremely healthy and < 50, the procedure is considered very low risk, and use of nephrotoxic drugs is not expected.

  • Liver tests are often measured if abnormalities are suspected based on the patient’s history or examination.

  • Coagulation studies and bleeding time are needed only if patients have a personal or family history of bleeding diathesis or a disorder associated with bleeding.

  • ECG is done for patients at risk of coronary artery disease (CAD), including all men > 45 and women > 50, and for severely obese patients (body mass index ≥ 40 kg/m2) with at least one risk factor for atherosclerotic cardiovascular disease (eg, diabetes, smoking, hypertension, or hyperlipidemia) or poor exercise tolerance (4).

  • Chest x-ray only in patients with symptoms of or risk factors for underlying cardiopulmonary disease.

  • Pulmonary function testing may be done if patients have a known chronic pulmonary disorder or symptoms or signs of pulmonary disease.

Patients with symptomatic CAD need additional tests (eg, stress testing, coronary angiography) before surgery.

Testing references

  • 1. Fleisher LA, Fleischmann KE, Auerbach AD, et al: ACC/AHA 2014 guideline on perioperative cardiovascular evaluation and management of patients undergoing noncardiac surgery (executive summary); a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines. Circulation 130:2215-2245, 2014. doi: 10.1161/CIR.0000000000000105

  • 2. O'Neill F, Carter E, Pink N, et al: Routine preoperative tests for elective surgery: summary of updated NICE guidance. BMJ 354:i3292, 2016. doi:10.1136/bmj.i3292

  • 3. Feely MA, Collins CS, Daniels PR, et al: Preoperative testing before noncardiac surgery: guidelines and recommendations. Am Fam Physician 87(6):414-418, 2013.

  • 4. Poirier P, Alpert MA, Fleisher LA, et al: Cardiovascular evaluation and management of severely obese patients undergoing surgery: a science advisory from the American Heart Association. Circulation 120(1):86-95, 2009. doi:10.1161/CIRCULATIONAHA.109.192575

Procedural Risk Factors

Procedural risk is highest with the following:

  • Heart or lung surgery

  • Hepatic resection

  • Intra-abdominal surgeries that are estimated to require a prolonged operative time or that have a risk of large-volume hemorrhage (eg, Whipple procedure, aortic surgery, retroperitoneal surgery)

  • Open prostatectomy

  • Major orthopedic procedures (eg, hip replacement)

Patients undergoing elective surgery that has a significant risk of hemorrhage should consider banking blood for autologous transfusion should it be needed. Autologous transfusion decreases the risks of infection and transfusion reactions.

Emergency surgery has a higher risk of morbidity and mortality than the same surgery done electively.

Patient Risk Factors

The contribution of patient risk factors to perioperative morbidity and mortality is best estimated by validated quantitative risk calculators. For example, the American College of Surgeons National Surgical Quality Improvement Program (ACS NSQIP) has developed a risk calculator to predict perioperative adverse events (see ACS NSQIP Surgical Risk Calculator). Use of these tools not only allows uniformity in interpreting surgeons' outcomes data but also contributes to better shared decision-making and informed consent for patients and family members (1).

Older age is associated with decreased physiologic reserve and greater morbidity if a complication occurs. However, chronic disorders are more closely associated with increased postoperative morbidity and mortality than is age alone. Older age is not an absolute contraindication to surgery.

Cardiac risk factors

Cardiac risk factors dramatically increase surgical risk. Perioperative cardiac risk is typically assessed using the American College of Cardiology/American Heart Association's Revised Cardiac Risk Index (see Figure: Algorithm for risk stratification for noncardiac surgery). It considers the following independent predictors of cardiac risk:

  • History of coronary artery disease (CAD)

  • History of heart failure

  • History of cerebrovascular disease

  • Diabetes requiring treatment with insulin

  • Serum creatinine (2.0 mg/dL)

Risk of cardiac complications increases with increasing risk factors:

  • No risk factors: 0.4% (95% confidence interval 0.1 to 0.8%)

  • 1 risk factor: 1.0% (95% confidence interval 0.5 to 1.4%)

  • 2 risk factors: 2.4% (95% confidence interval 1.3 to 3.5%)

  • ≥ 3 risk factors: 5.4% (95% confidence interval 2.8 to 7.9%)

A high-risk surgical procedure (eg, vascular surgery, open intrathoracic or intraperitoneal procedure) also independently predicts a high cardiac perioperative risk.

Patients with active cardiac symptoms (eg, of heart failure or unstable angina) have a particularly high perioperative risk. Patients with unstable angina have about a 28% risk of perioperative myocardial infarction. In patients with stable angina, risk is proportional to their degree of exercise tolerance. Patients with active cardiac symptoms thus require thorough evaluation. For example, the cause of heart failure should be determined so that perioperative cardiac monitoring and treatment can be optimized before elective surgery. Other cardiac testing, such as stress echocardiography or even angiography, should be considered if there is evidence of reversible cardiac ischemia on preoperative evaluation.

Preoperative care should aim to control active disorders (eg, heart failure, diabetes) using standard treatments. Also, measures should be taken to minimize perioperative tachycardia, which can worsen heart failure and increase risk of myocardial infarction; for example, pain control should be optimized and beta-blocker therapy should be considered, especially if patients are already taking beta-blockers. Coronary revascularization should be considered for patients with unstable angina. If a heart disorder cannot be corrected before surgery or if a patient is at high risk of cardiac complications, intraoperative and sometimes preoperative monitoring with pulmonary artery catheterization may be advised. Sometimes the cardiac risk outweighs the benefit of surgery. In such cases, a less invasive procedure may provide or serve as a bridge to definitive treatment (eg, tube cholecystostomy for cholecystitis) and decrease morbidity and mortality.

Algorithm for risk stratification for noncardiac surgery

*Active clinical conditions include unstable coronary syndromes, decompensated heart failure, significant arrhythmias, and severe valvular disorders.

See the ACC/AHA

Clinical risk factors include coronary artery disease, history of heart failure, history of cerebrovascular disease, diabetes mellitus, and preoperative creatinine > 2.0 mg/dL.

ACC = American College of Cardiology; AHA = American Heart Association; HR = heart rate; MET = metabolic equivalent.

Adapted from Fleisher LA, Beckman JA, Brown KA, et al: ACC/AHA 2007 guidelines on perioperative cardiovascular evaluation and care for noncardiac surgery; a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines. Fleisher LA, Fleischmann KE, Auerbach AD, et al

Algorithm for risk stratification for noncardiac surgery


Incidental bacterial infections discovered preoperatively should be treated with antibiotics. However, infections should not delay surgery unless prosthetic material is being implanted; in such cases, surgery should be postponed until the infection is controlled or eliminated.

Patients with respiratory infections should be treated and have evidence that the infection has resolved before receiving inhalational anesthesia.

Viral infections with or without fever should be resolved before elective surgery is done, especially if a general anesthetic is going to be used.

Fluid and electrolyte imbalances

Fluid and electrolyte imbalances should be corrected before surgery. Hypokalemia, hyperkalemia, hypocalcemia, and hypomagnesemia must be corrected before general anesthesia to decrease risk of potentially lethal arrhythmias. Dehydration and hypovolemia should be treated with IV fluids before general anesthesia to prevent severe hypotension on induction—blood pressure tends to fall when general anesthesia is induced.

Nutritional disorders

Undernutrition and obesity increase the risk of postoperative complications in adults. Nutritional status is assessed preoperatively using history, physical examination, and laboratory tests.

Severe nutritional risk factors include the following:

  • A body mass index < 18.5 kg/m2 or a history of unintentional weight loss > 10% of body weight over 6 months or 5% over 1 month

  • Suggestive physical examination findings (eg, muscle wasting, signs of specific nutritional deficiencies)

  • Low serum albumin levels (< 3 g/dL without evidence of renal or hepatic dysfunction)

It is important to ask whether weight loss was intentional, because unintentional weight loss may reflect a catabolic state refractory to nutritional repletion, suggesting serious underlying pathology such as cancer.

Serum albumin is an inexpensive, widely available, and reliable indicator of undernutrition; it should be measured preoperatively in patients who may be undernourished. Values < 2.8 g/dL predict increased morbidity (including poor wound healing) and mortality. Because the half-life of serum albumin is 18 to 20 days, levels may not reflect acute undernutrition. If more acute undernutrition is suspected, a protein with a shorter half-life can be measured; for example transferrin (half-life 7 days) or transthyretin (pre-albumin; half-life 3 to 5 days). Preoperative and perioperative nutritional support with the aid of a dietitian to prevent and treat specific nutritional and electrolyte deficiencies is most likely to improve outcomes in patients whose histories of weight loss and protein levels indicate severe undernutrition (2). In some cases, surgery can be delayed so patients can receive nutritional support, sometimes for several weeks (eg, in chronically undernourished patients, to help prevent the refeeding syndrome).

Significant obesity (body mass index > 40 kg/m2) increases perioperative mortality risk because such patients have increased risk of cardiac and pulmonary disorders (eg, hypertension, pulmonary hypertension, left ventricular hypertrophy, heart failure, coronary artery disease). Obesity is an independent risk factor for deep venous thrombosis and pulmonary embolism; preoperative venous thromboembolism prophylaxis is indicated in most obese patients. Obesity also increases risk of postoperative wound complications (eg, fat necrosis, infection, dehiscence, and abdominal wall hernias).

Patient risk factor references

  • 1. Bilimoria KY, Liu Y, Paruch JL, et al: Development and evaluation of the universal ACS NSQIP surgical risk calculator: A decision aid and informed consent tool for patients and surgeons. J Am Coll Surg 217(5):833-42.e423, 2013. doi:10.1016/j.jamcollsurg.2013.07.385

  • 2. Weimann A, Braga M, Harsanyi L, et al: ESPEN guidelines on enteral nutrition: Surgery including organ transplantation. Clin Nutr 25:224–244, 2006. doi: 10.1016/j.clnu.2006.01.015

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