Preoperative evaluation of apparently healthy patients is a common activity for internists and other medical specialists. In general, the most important test is a careful medical history to seek elements which may increase perioperative risk above baseline. Individual laboratory and other tests should be ordered selectively based on patient and procedure-related characteristics, and in general, should not be done routinely without a clinical indication. Despite decades of evidence arguing against routine testing, medical culture is such that some of this testing persists. General rationales for ordering preoperative tests are to identify patients at higher risk for particular postoperative complications, to guide anesthetic management, to predict which patients require particular monitoring after surgery, and for medicolegal reasons. In fact, in most instances, testing for any of these indications rarely achieves the desired goals. In this chapter, we discuss the recommended selective indications for testing.
If enough routine tests are ordered, it is likely that one or more tests may be abnormal due to the typical definition of normal as within 2 standard deviations from the mean. This means, by definition, that in 5% of patients without underlying disease, a test will be abnormal. If tests are done routinely, an abnormal test result may result in an unnecessary delay of surgery, patient worry, and additional testing which may be costly, and in some cases, carry risk for the patient. A selective approach to preoperative test ordering avoids this trap.
Commonly, the results of preoperative testing do not actually change perioperative care. Results are more likely to be ignored or overlooked rather than guide perioperative care. An optimal test would be one that accurately identified patients at risk of postoperative complications who would otherwise be characterized as low-risk based on a history and physical, is inexpensive, carries little risk, and has a high sensitivity and specificity. Few tests have these qualities.
Increasingly, surgeons, anesthesiologists, and hospital standards committees have recognized this fact and are requiring fewer routine tests than had been the case historically. For example, in the Choosing Wisely guidelines, national societies were given the chance to list five things that we should question or not do. Many of the relevant surgery and anesthesiology guidelines made a recommendation to avoiding unnecessary preoperative testing.1 At least 13 different societies chose recommendations to limit preoperative testing. Table 2-1 summarizes these recommendations. In 2012, the American Society of Anesthesiologists stated in a practice advisory that “preoperative tests should not be ordered routinely…tests may be ordered, required, or performed on a selective basis for purposes of guiding or optimizing perioperative management.”2
TABLE 2-1Choosing Wisely Campaign. Society Recommendations to Limit Preoperative Testing ||Download (.pdf) TABLE 2-1 Choosing Wisely Campaign. Society Recommendations to Limit Preoperative Testing
American Society of Hematology-American Society of Pediatric Hematology/Oncology
Don't perform routine preoperative hemostatic testing (PT, aPTT) in an otherwise ...