Preoperative Evaluation

Preparation for surgery begins long before the day of the operation and involves determining the risk-to-benefit ratio for each individual patient. Understanding how to appropriately evaluate a patient for surgery is an important skill in both the outpatient and inpatient settings. The preoperative evaluation begins with a thorough history and physical, followed by tailored consideration of each patient’s comorbidities and risk factors. Completing this evaluation informs the decision to proceed with surgery while minimizing the patient’s risk of intraoperative and postoperative complications.

This section focuses on how to identify important risk factors from history and laboratory findings that can be modified or optimized in preparation for surgery. The information presented in this section primarily applies to the elective surgery setting but can be adapted for urgent or emergent situations.

The topics in this rotation guide are organized as follows:

• History and Physical Examination

• Laboratory Studies

• Risk Stratification and Optimization

• Perioperative Nutritional Management

• Perioperative Pain Management

• Tobacco, Alcohol, and Drug Use

• Special Circumstances

• Preoperative Preparation

History and Physical Examination

The history and physical examination are critical components of the preoperative evaluation and provide valuable information about the patient’s overall health and any conditions that may increase risk for complications during surgery.

Preoperative History

Ideally, a patient should present for evaluation several weeks before surgery. A thorough history should include:

• history of the presenting illness, with a focus on symptoms, timing, and other therapies related to the condition for which the procedure is planned

• medical history, with specific attention to assessment of chronic conditions that may affect surgery (e.g., diabetes, hypertension, heart disease, or pulmonary disease)

• surgical history, including history of adverse responses to anesthesia

• allergies and medications, particularly medications that may need to be adjusted or held prior to surgery (e.g., antiplatelets and anticoagulants)

• social history, including tobacco, alcohol, and illicit drug use, as well as functional status and social supports

  • Smoking should be stopped at least 8 weeks before surgery to minimize surgical risk.

  • Understanding a patient’s functional status and social support can help identify individuals who may benefit from home services or postprocedural rehabilitation.

• family medical history, with particular attention to bleeding disorders and difficulty with anesthesia

Focused Physical Exam

Information acquired during the history should inform the physical exam.

• As with standard physical exams, the patient’s vital signs and cardiac, pulmonary, and neurologic status should be assessed.

• Perform a thorough exam of the area undergoing surgery (e.g., identify scars on the abdomen that may hint at a past surgical history).

• Note exam findings during the cardiopulmonary evaluation that may warrant additional workup (e.g., elevated blood pressure, cardiac murmurs, signs of heart failure, chronic obstructive pulmonary disease [COPD]).

• Examine the airway to assess potential intubation challenges.

• Note signs of frailty or malnutrition.

The following table summarizes history and physical exam findings that suggest the need for further evaluation.

Laboratory Studies

Laboratory studies can provide additional information about the patient’s overall health and medical conditions that could affect their surgical procedure. However, laboratory tests should be ordered selectively based on the indications in an individual patient.

• Hemoglobin: A hemoglobin measurement is useful for detecting unexpected anemia, or to obtain a baseline for potentially complex surgeries with the potential for significant blood loss.

• Glucose: Preoperative glucose screening is recommended in patients aged ≥40 years. Diabetes mellitus increases perioperative risk.

• Urine pregnancy tests: Consider in patients of childbearing age.

• Coagulation studies: Consider in patients on anticoagulation therapy, with evidence of liver disease, or those with personal or family history of bleeding disorders.

The following table lists indications for additional preoperative tests based on information obtained from the history and physical exam.

(Source: Preoperative Evaluation and Preparation for Anesthesia and Surgery. Hippokratia 2007.)

Risk Stratification and Optimization

Risk stratification involves assessing a patient’s overall risk for complications during and after surgery. The following tools are used to estimate morbidity and mortality risk, identify patients who require further evaluation, and guide discussions around informed consent:

• American Society of Anesthesiologists Physical Status Classification (ASA-PS)

  • This tool assesses and classifies the patient’s fitness for surgery and stratifies surgical risk.

  • It is used to guide appropriate preoperative workup (e.g., patients classified as either class III or class IV who have cardiovascular or renal conditions are advised to undergo renal function testing and a complete blood count [CBC] prior to surgery).

  • The classification does not consider various patient- or procedure-specific factors and thus has limitations in optimizing preoperative preparation.

• Revised Cardiac Risk Index (RCRI)

  • This index is used to specifically assess cardiac risk in noncardiac surgery patients.

  • It incorporates several patient-specific cardiac risk factors to provide an overall risk score for major cardiac events (more risk factors indicate higher risk).

  • Based on the risk score, a patient may require an ECG, left ventricular function assessment, or exercise or pharmacologic stress testing prior to surgery.

• American College of Surgeons National Surgical Quality Improvement Program (NISQIP) Risk Calculator

  • This tool estimates risk of postoperative complications, including cardiac complications, postoperative infections, venous thromboembolism, readmission, reoperation, and death.

  • It enables customization of perioperative management based on specific patient risk factors (e.g., preoperative management in patients with COPD should be tailored to minimize pulmonary complications, including smoking cessation and preoperative respiratory conditioning).

(Source: ACS NSQIP Surgical Risk Calculator.)

(Source: ACS NSQIP Surgical Risk Calculator.)

Perioperative Nutritional Management

Nutritional status is an important factor to consider when preparing patients for surgery. After surgery, patients often enter a high catabolic state as a result of increased nutritional needs for healing and occasional reduced gastrointestinal function. Thus, patients may be at risk for malnutrition, which is associated with increased risk of complications after surgery, including poor wound healing, infection, and even death. (For in-depth information, see Nutritional Support in Surgical Patients in this rotation guide.)

• Consider assessment for malnutrition in high-risk patients, including patients with cancer, elderly patients, and patients with recent weight loss.

• Preoperative nutritional evaluation includes obtaining a serum albumin level.

  • A serum albumin of <3 mg/dL is associated with increased postoperative morbidity.

• Serum transferrin and pre-albumin measures can be used as short-term markers for nutritional status.

• Consider preoperative nutritional supplementation in patients with some or moderate levels of malnutrition.

• Preoperative full nutritional support is typically reserved only for severely malnourished patients.

Perioperative Pain Management

Surgery is an invasive procedure, and patients often require postoperative pain medication to ease discomfort and minimize movement and breathing limitations. Patients should be counseled about anticipated pain levels after surgery and the expected pain control regimen. Other factors to consider when deciding on perioperative pain control include the following:

• In patients who are already receiving long-term opioid regimens or have a history of opioid use disorder:

  • Preoperative opioid use is associated with increased risk of postoperative complications, more-challenging pain management, and longer hospital stay following surgery.

  • Patients using methadone or buprenorphine for management of opioid use disorder may have difficulty with adequate postoperative pain control.

  • Acute pain specialists should be involved in postoperative care of this patient population to assure adequate pain control.

• Set expectations about pain and pain medication during the preoperative evaluation:

  • Discuss typical postoperative pain medication requirements, opioid needs, alternative pain regimens, and risks of prolonged opioid use.

  • Counsel patients about the possibility of prolonged opioid use after major surgery and the increased risk of dependence and overdose.

  • Use institutional postoperative opioid prescribing guidelines as a reference if available.

Tobacco, Alcohol, and Drug Use

Tobacco, alcohol, and illicit drug use can each increase the risk of complications during and after surgery. An understanding of the risks of substance use is critical to preventing certain complications.

• Cigarette smoking is considered a chronic disease in the ASA-PS classification.

• Smoking increases risk of pulmonary complications and poor wound healing.

  • Smoking cessation 4 to 8 weeks prior to surgery successfully mitigates the increased risk of complications.

  • Smoking after surgery is associated with impaired healing. Patients should be counseled to not smoke for at least 8 weeks postoperatively.

• Alcohol use disorder predisposes patients to postoperative delirium and alcohol withdrawal, as well as infectious, cardiac, and pulmonary complications.

  • Patients at risk of these complications should be prescribed postoperative benzodiazepines or phenobarbital for withdrawal, thiamine to prevent Wernicke encephalopathy, and multivitamins for possible malnutrition.

• Several illicit drugs can lead to increased perioperative risks.

  • Cocaine toxicity can lead to cardiac ischemia, arrhythmias, and stroke.

  • Opioid abuse can lead to respiratory depression and prolonged ileus.

Special Circumstances

For certain patient populations, additional considerations for the preoperative evaluation include:

Elderly patients:

• Frailty should be evaluated when considering surgery in an older patient.

  • Frailty is a measure of a patient’s physiologic reserve and is most commonly assessed using the frailty phenotype, which requires three of the following five characteristics:

    • weight loss

    • self-reported exhaustion

    • low physical activity

    • slow walking speed

    • weakness

• Increased frailty has been shown to be a better predictor than chronologic age of postoperative complications, length of hospital stay, and discharge to a skilled nursing or assisted-living facility.

Pregnancy:

• Elective surgeries are usually postponed until after birth in pregnant patients unless urgent or emergent surgery is required.

• Postoperative morbidity and mortality in pregnant patients are generally the same as in nonpregnant patients.

  • However, pregnant patients are at increased risk of obstetric complications, including preterm labor and miscarriage.

  • To reduce the risk of obstetric complications, surgeries are preferentially performed laparoscopically and scheduled during the second trimester.

Preoperative Preparation

Once the patient has undergone appropriate workup and the decision has been made to proceed with surgery, the following additional steps in the immediate preoperative period can reduce surgical risk.

Bowel preparation:

• Bowel preparation is typically performed for colorectal procedures and decreases risk of wound infection and anastomotic leak and increases intraoperative mobility of the bowel.

• Bowel prep typically involves the use of mechanical bowel preparation with stimulant or osmotic laxatives to decrease stool burden in the colon and antibiotics (e.g., neomycin and erythromycin) to reduce the risk of infective complications.

Preoperative prophylactic antibiotics:

• Preoperative prophylactic systemic antibiotics should be administered within 60 minutes of incision.

• The choice of antibiotics is guided by the anticipated wound classification based on level of contamination and the potential organisms that may cause infection after a specific procedure.

Evaluation of venous thromboembolism (VTE) risk:

• Reduced mobility after surgery increases the risk of VTE. (See Mobilization in this rotation guide.)

• The body’s inflammatory response after surgery places patients in a transient hypercoagulable state that increases the risk of VTE.

• The Caprini Risk Assessment Model can be utilized to determine a patient’s VTE risk after surgery and during hospitalization, with higher scores associated with increased risk.

The following table outlines the VTE prophylaxis recommendations for patients undergoing general, abdominal, pelvic, bariatric, vascular, and plastic surgery based on their Caprini risk scores.