Screening Services

Because screening can be a medically appropriate service, but is not a Medicare benefit and so not paid by Medicare, the clinician must be able to distinguish screening from (for lack of a better phrase) diagnostic services. What follows is an attempt to define screening so that the clinician can better make this distinction. This definition does not claim universal application (a public health worker may have a different one) but is offered to distinguish between screening and diagnostic services for the purpose of resolving Medicare issues. The method by which the definition is made will involve defining what screening is and what it is not, given that the boundaries of a concept are made more clear when both sides of the boundary are described.

Summary of Issues

  • Screening services are those used to detect an undiagnosed disease where early detection may prevent harm, and where the patient has no signs, symptoms, laboratory evidence, radiological evidence or personal history of the disease.
  • Diagnostic services are those used to manage a diagnosed disease or to evaluate symptoms, signs and abnormal laboratory or radiological findings in order to make a diagnosis.
  • Testing the preoperative patient for an undiagnosed disease that may increase the operative risk and testing the patient for a disease for which the patient has a family history are both, in the absence of signs, symptoms, abnormal laboratory or radiological findings, or a personal history, types of screening.
  • Testing a patient for an infectious disease when there has been a recent and significant exposure to that disease is a diagnostic service even though the patient has no symptoms or signs of the disease.
  • While both diagnostic and screening services may be appropriate, screening services are not (with some exceptions) covered by Medicare.
  • A procedure that begins as screening but uncovers significant pathology that requires attention at that time becomes a diagnostic procedure. This is not generally true for screening tests.


A screening service for Disease X is one that is performed for a patient who has neither symptoms, abnormal findings (physical, laboratory or radiological) or any past history of Disease X. The purpose of this service is to determine if the patient has Disease X so that medical care can begin, the aim being to reduce or prevent suffering. The attributes of Disease X that justify screening include 1) the probability that the patient has the disease, 2) the burden of suffering that the untreated disease entails, 3) the probability that medical care will be effective in reducing this suffering and 4) the risk of failing to diagnose and treat. The second, third, and fourth attributes should be of significant intensity to justify screening, although "significant intensity" may vary from modest to profound. Thus, concerning 2) and 4), hearing and vision impairment have a more modest burden of suffering and less risk if not diagnosed than colon cancer. For 3), the probability that treatment will be effective might be low for some cancers, high for some metabolic diseases. In contrast, the first attribute is usually low and need not be high to justify screening.

A diagnostic service is one done for a patient who has Disease X (the probability is 100%, presuming that the diagnosis is correct) or who has symptoms or findings that suggest Disease X. The probability that this patient with these symptoms or findings has Disease X is much higher than that for a patient without these symptoms, findings or past history, i.e., the patient for whom one is performing a screening service to detect Disease X. Further, attributes 2) and 3) above apply to diagnostic as well as screening services and vary from quite modest (the uncomplicated URI) to profound (some leukemias). Thus, one attribute that most clearly distinguishes the screening service from the diagnostic service is the probability that the patient has the disease, high to 100% for the diagnostic services, and low for the screening services.

This claim for probability as the distinguishing feature raises at least three issues. First, preoperative testing to detect and evaluate a disease that may be made worse by the surgery is diagnostic if the patient has the disease, screening if the patient doesn't. Thus, a pre-operative chest film on a patient with COPD and an ECG on a heart patient are diagnostic, but screening if the patient has no signs, symptoms, abnormal laboratory or radiological findings, or personal history for which these tests are relevant. While the risk of failure to diagnose a disease for which the patient has no evidence prior to surgery in the Medicare population may be higher than in the general population, risk alone does not distinguish a screening from a diagnostic test, and does not allow the claim that these tests are not screening and should therefore be billable as diagnostic.

Second, the person with a family history of Disease X has a higher probability of having or getting that disease than the general population, presuming that Disease X is to some degree inherited. Monogenic Mendelian disorders result from one to a few chromosomal abnormalities and will be usually identified long before age 65. In contrast, the "multifactorial disorders," e.g., essential hypertension, that result from multiple genetic and environmental factors may arise after 65. Harrison's Principles of Internal Medicine, Fourteenth Edition, states on Page 387 that the multifactorial disorders "usually affect no more than 5 to 10 percent of first degree relatives." Thus, while a family history of a disease increases the probability of a patient having that disease, the probability is still lower than it is for a patient who presents with a clinical picture compatible with the disease. Accordingly, for the purpose of resolving Medicare issues, and setting aside those screening tests for which Congress has created a Medicare benefit, services aimed at detecting a familial disease in a patient without symptoms, abnormal findings or personal history of that disease are considered screening.

Third, a person with a recent and significant exposure to an infectious agent may have no symptoms or findings that suggest infection. Still, with a recent (the incubation period hasn't ended) and significant exposure, the probability of the patient having this infection is much higher than that for the general population, although this probability depends on how contagious the agent is and the degree of exposure, and so may vary over a wide range. Accordingly, testing for an infection in this situation may be considered diagnostic and not screening.

Because some services (evaluation and management services and procedures such as endoscopies) take place over time, in contrast to tests (laboratory, physiological, imaging) that report a condition at a point in time, these services may begin as screening but uncover a significant medical problem which should be addressed at that time. These services become diagnostic (or perhaps therapeutic) though they began as screening. Thus, a significant symptom elicited on system review or an abnormal physical finding discovered during what began as a routine annual screening examination changes that encounter to diagnostic. In contrast, a test that began as screening remains screening even though it is reported some time later as abnormal.

The services that may be either diagnostic or screening include (E/M) services, clinical laboratory tests, physiologic tests (ECGs, EEGs, etc.) and imaging studies. Because Medicare chart reviews commonly encounter records that do not clearly distinguish between diagnostic and screening services, it may be necessary to ask why the service was given. There are many reasons for performing a service and so one needs to distinguish between at least two different uses of "reason."

First, a "justifying reason" is a reason that results from accurate data and logical analysis of the data and justifies the action taken. Thus a history of bloody stools, plus a confirmatory positive occult blood test, justify a colonoscopy. An "explanatory reason," one that merely explains why but does not justify an action, may involve incomplete or inaccurate data and either faulty or no logic. Thus, one may claim that the CBC and Chem 19 tests were ordered because the patient complained, over the phone, of fatigue, a symptom without a diagnosis. But in the absence of a history and examination (when done properly, these will give a diagnosis in the great majority of encounters), this reason, the need to make a diagnosis, explains but does not justify the tests.

Reasons for Performing or Ordering a Service or Test

  • Symptoms: The patient's symptoms suggested a significant medical problem that was not resolved by the history and physical examination and the service in question may give an answer.
  • Signs: On physical examination, the physician found a significant and new abnormality, that may be explained by the service ordered.
  • Past History:
    • Past symptoms, no longer present, may require reevaluation
    • Past abnormal physical findings, no longer present, may require reevaluation
    • Patient had a disease that may be asymptomatic but requires periodic monitoring
    • Patient was taking a drug or some other therapy that required periodic monitoring
    • Patient was in postoperative period of a diagnostic or therapeutic procedure and a service was ordered or given to monitor the patient's progress or to assess possible complications
  • Abnormal Findings on Laboratory or Radiological Tests: In the absence of symptoms, signs or abnormal significant past history, abnormal test results may require further testing.
  • Screening: None of the above conditions applies, but because a disease may have no early symptoms or signs, and because early diagnosis may improve the clinical outcome, a service to rule in or out that diagnosis is ordered.
  • Liability: Though none of the above reasons apply, the physician may wish to limit liability (defensive medicine) and so performs the service.
  • Error: The physician or an assistant ordered the wrong test by mistake.
  • Habit: Though none of the above apply, the physician has always performed or offered this service.
  • Faulty Reasoning: The physician believed that a test result might have some bearing on the clinical picture, but this belief was incorrect.
  • Curiosity: The physician or patient "just wanted to know" and none of the above apply.
  • Patient Demand: The patient is more than curious. He or she demands that the test be done because of some belief (perhaps well founded) that it will benefit him or her.
  • Financial Gain: Because the provider is paid for the service, and in spite of the fact that none of the above reasons applies, the service is performed.

The first five reasons, and perhaps the sixth, are justifying reasons. Medicare considers only the first four reasons as meeting the requirement of "reasonable and medically necessary" and so qualifying for coverage. These reasons identify those services that are diagnostic. While screening is good medical practice, it is, with some exceptions, not covered by statute. Reasons 7) through 12) are not justifying reasons, i.e., they do not justify the service as either diagnostic or screening. They explain why the physician ordered or gave the service (I goofed, I always do it, I was mistaken, I was curious, the patient insisted, I am greedy) but do not justify the service.

Evaluation and Management services, like tests, may be either diagnostic or screening. The "yearly exam" of, or any visit by an asymptomatic person whose past history contains none of the items listed under 3) above and who has no record of abnormal tests, is a screening service.

To summarize, in considering the screening/diagnostic distinction, Medicare covers those services that are medically necessary, defined here by Reasons 1-4, and labeled diagnostic services. They address either known or highly probable diseases. Screening services are defined by Reason 5, and address diseases of low probability, and for which the patient has no signs, symptoms or history. The remaining seven reasons identify services that are neither diagnostic nor screening and have little (Reason 6) or no justification.


Last Updated Dec 09 , 2022