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The role of testing in the preoperative evaluation

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ABSTRACT

Preoperative laboratory and electrocardiographic testing should be driven by the patient’s history and physical examination and the risk of the surgical procedure. A test is likely to be indicated only if it can correctly identify abnormalities and will change the diagnosis, the management plan, or the patient’s outcome. Needless testing is expensive, may unnecessarily delay the operation, and puts the patient at risk for unnecessary interventions. Preoperative evaluation centers can help hospitals standardize and optimize preoperative testing while fostering more consistent regulatory documentation and appropriate coding for reimbursement.

KEY POINTS

  • Age-based criteria for preoperative testing are controversial because test abnormalities are common in older people but are not as predictive of complications as information gained from the history and physical exam.
  • Pregnancy testing is an example of an appropriate pre­operative test because pregnancy is often not detectable by the history and physical exam and a positive result would affect case management.
  • Routine ordering of preoperative electrocardiograms is not recommended because they are unlikely to offer predictive value beyond the history and physical exam and are costly to an institution over time.
  • Routine and aged-based preoperative tests are no longer reimbursed by the Centers for Medicare and Medicaid Services.


 

References

Routine presurgical assessment of patients with a standard battery of tests not only is wasteful but can lead to more unnecessary expense, delay, and even risk to the patient and physician. Any abnormal tests results, even if likely to be clinically unimportant to the upcoming surgery, will need to be followed up to rule out a significant abnormality that may have later implications. This review will outline strategies for making decisions about which tests are clinically useful for preoperative assessment of a given patient and also discuss the value of preoperative evaluation centers in promoting appropriate preoperative testing.

PREOPERATIVE EVALUATION SHOULD BE CLEARLY DIRECTED

Most patients scheduled for surgery at Brigham and Women’s Hospital are assessed by the staff at our preoperative evaluation center. We take a medical history and conduct a physical examination, review the medical records, order laboratory tests or other studies as indicated, and determine which patients need further work-up or consultations. The goals are to evaluate patient readiness for anesthesia and surgery, optimize patient health before surgery, enhance the quality of perioperative care, reduce the morbidity of surgery and length of stay, and return the patient to normal functioning.1,2

The above goals are generally achieved by directed laboratory testing, managing the patient’s medications, stabilizing disorders when possible, and creating plans for postoperative care and pain management. Communication among the surgeon, the anesthesiology team, and the preoperative medical consultant (if there is one) is critical.1,2

In contrast, “clearing the patient for surgery” is not a legitimate goal of consultation. The real issues to be taken up in a consult are:

  • What is the patient’s risk of complications (cardiac and noncardiac)?
  • Would further risk stratification alter patient management?
  • Can anything be done to reduce the patient’s risk?

If indicated, a consult should cover the entire perioperative period, offering opinions on operative risk and suggesting treatments that affect long-term patient outcomes. Rarely is preoperative intervention necessary just to lower the risk of surgery. Most interventions that are needed should be done regardless of the surgery.

Everyone on the medical team should have the goal of efficient resource utilization, including avoidance of unnecessary visits, laboratory testing, and consultations.

PREOPERATIVE TESTING: WHAT IS NEEDED?

Preoperative testing is extremely expensive: even more than 20 years ago, preoperative medical testing for all types of surgery accounted for approximately $30 billion in US health care costs annually.3 The likelihood of abnormal test results increases with age, and the more tests performed, the more likely a false positive will occur, further driving up costs.

Preoperative testing should generally be directed by a targeted history and physical examination, and the relevance of any tests should be considered in light of the type of procedure that is planned, particularly the hemodynamic changes and blood loss involved. Before ordering a test, physicians should be sure that there is a good reason for the test, that it is consistent with established guidelines, and that the results will be useful (ie, have the potential to change management).

Case study: Inguinal surgery in a healthy elderly man

A 72-year-old man is being evaluated prior to a right inguinal herniorrhaphy. He has osteoarthritis but is otherwise healthy and jogs 3 to 5 miles several times a week. He takes no medications and has no known drug allergies.

Question: Which of the following tests is necessary prior to surgery?

A. Complete blood cell count (CBC)

B. Prothrombin time and partial thromboplastin time

C. Electrocardiogram (ECG)

D. All of the above

E. None of the above

The correct answer is E (none of the above), for the reasons laid out in the following section.

Unnecessary testing may cause more harm than good

Untargeted testing should be avoided. An unexpected result will probably not be clinically significant for the surgery and will only lead to more needless testing, unnecessary anxiety for the patient, and delays in proceeding to the operating room.4 The more tests that are ordered, the higher the likelihood of having an abnormal result by chance: for a test with 95% specificity, results for 1 out of 13 ordered tests will likely be abnormal without there being a true underlying physiologic abnormality.

Researchers at Johns Hopkins University assessed the value of routine preoperative medical testing in a randomized study of nearly 20,000 patients undergoing elective cataract surgery whose preoperative history and physical examination was either preceded or not preceded by a standard battery of tests, including ECG, CBC, electrolytes, urea nitrogen, creatinine, and glucose.5 This was an ideal study population, given the relatively noninvasive nature of the procedure (with minimal hemodynamic changes) and cataract patients’ relatively advanced age and resulting likelihood of comorbidities. Notably, there were no differences between the two groups in the overall rate of complications (approximately 3%), which led the researchers to conclude that routine preoperative medical testing does not increase the safety of cataract procedures. These results could be applied to other low-risk cases.

Unnecessary testing is also expensive. Researchers at Stanford University Hospital retrospectively compared preoperative test orders during 6-month periods before and 1 year after development of an anesthesia preoperative evaluation clinic.6 They found a 55% reduction in the number of preoperative tests ordered from the period before the clinic was established, when tests were ordered by surgeons and primary care physicians, to the period after the clinic was established, when test ordering was transferred to anesthesiologists at the clinic. This reduction in the number of tests ordered resulted in a 59% reduction in the hospital’s expenditures for preoperative tests, yielding $112 in cost savings per patient. No operating room cancellations, delays, or adverse patient events were reported as a result of the change.

Similar results were reported more recently by researchers at a Canadian hospital, who found that selective preoperative test ordering by staff anesthesiologists reduced the number and cost of preoperative studies compared with usual practice without a resulting increase in complications.7

What are the real legal risks?

Many surgeons express the fear that they will be sued if they do not routinely order preoperative tests. My view is that from a medicolegal standpoint, it is usually better not to order an unnecessary test if the next step to take in the event of an abnormal result would be unclear. The legal risk is greater for not following an abnormal test result than for not ordering a test that was not indicated. One may uncover an abnormal laboratory test finding that is not likely to be clinically significant but that could result in legal action if it were not evaluated further. A complication that may not be related to the abnormal result may develop at some point in the future and be blamed on the lack of follow-up. At our center, we insist that when a physician orders a test, he or she is responsible for the results and for following up on abnormalities.

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