When is a “diagnostic test” actually a “medical procedure”?

Dear Readers, What is the difference between a “medical test” and a “diagnostic procedure”? According to Wikipedia,[1] “a medical test is a kind of medical procedure performed to detect, diagnose, or evaluate disease, disease processes, susceptibility, and determine a course of treatment.” However, physicians do not use the terms “test” and “procedure” interchangeably. The word “procedure” usually implies something invasive. But what is the definition of invasive? A medical test is typically a noninvasive diagnostic test that is not associated with “significant risk” to the patient. An example is an electrocardiogram. When ordering a medical test, the physician must consider the appropriateness and cost of the test but not the risks of the test; a physician orders a test. A diagnostic procedure, on the other hand, usually implies an invasive procedure that carries some risk. When considering a diagnostic procedure for a patient, the physician must weigh the risks and benefits of the procedure with the patient. A physician usually does not order an invasive procedure, but typically refers the patient to another physician who will be performing the procedure. The physician who will be performing the procedure evaluates the patient before the procedure, takes responsibility for obtaining consent and completes the procedure. An example of a procedure is a diagnostic EP study for risk stratification of sudden death. Occasionally, the physician who performs the diagnostic procedure does not meet the patient until immediately before the procedure. The culture in the coronary catheterization laboratory usually is one where the referring physician schedules the procedure, and the cardiologist meets the patient on the day of the procedure. In electrophysiology, most patients are evaluated before the day of the procedure by the physician who will be performing the procedure. Three recent encounters with different Radiology Departments highlight the problem that occurs when a non-invasive procedure that is associated with significant risks is considered a test rather than a procedure. The first encounter was with a Radiology Department scheduler, who was calling to inform the ordering physician that the task of obtaining preauthorization from the insurance company was the responsibility of the ordering physician. Insurance companies restrict access for medical imaging in some cases by requiring a physician phone call when preauthorization is denied. This can be time consuming. It seems unreasonable that the burden of obtaining preauthorization for payment is on anyone other than the physician who will be performing and billing for the procedure. The second encounter was from a Radiology Department trainee regarding a patient scheduled for cardiac magnetic resonance imaging (MRI) who had a mildly elevated serum creatinine. The Radiology Department policy at that institution apparently states that, because gadolinium contrast can be nephrotoxic, when a patient who is scheduled for an MRI with contrast has a low serum creatinine clearance, the referring physician must determine if hemodialysis is needed immediately after contrast is given. This particular patient had symptomatic persistent atrial fibrillation and a complication from a transesophageal echo (TEE) performed previously at an outside hospital with esophageal perforation. The TEE showed a left atrial appendage thrombus. It was determined after a discussion with the patient in clinic that an MRI would be a useful procedure to exclude a left atrial appendage thrombus prior to an attempt at cardioversion. She had mild renal insufficiency. When it was suggested that it should be the responsibility of the physician administering the contrast to have a conversation with the patient regarding the risks and benefits of the procedure, the only response was invocation of the policy. The third contact was from a nurse performing a cardiac MRI in a patient with claustrophobia. The ordering physician had scheduled the procedure with an anesthesiologist in advance of the procedure. When it was determined that 1mg of midazolam was insufficient for sedation after the anesthesiologist left, the nurse supervising the procedure notified the ordering physician for further direction. When asked who the radiology attending was who was performing the procedure that was requiring sedation, the nurse was unable to provide that information. There will always be disagreements between various groups within the health care field over issues like this. However, it should be fairly obvious that a test with significant risks, or a test that might require sedation to complete, is more than just a test. The term “diagnostic procedure” rather than “test” should be used when there is the potential for significant risks. The term “significant risk” is already familiar to physicians. The Investigational Device Exemption (IDE) regulations of the U.S. Food and Drug Administration describe two types of device studies, “significant risk” (SR) and “non-significant risk” (NSR). A diagnostic procedure, even a noninvasive diagnostic procedure, is not the same as a test when it carries significant risks, and at times requires sedation to complete. As such, the physician who is performing and billing for a diagnostic procedure should be responsible for obtaining preauthorization, determining if the risk/benefit ratio of the procedure is favorable, and taking responsibility for providing or arranging for sedation to complete the procedure.