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What you need to know about diagnostic tests

Test results are NOT a diagnosis of disease

Despite the availability of numerous sophisticated diagnostic tests and procedures, there are none that can provide with certainty a final answer in diagnosing diseases. This is due to differences in accuracy. There is no guarantee of complete accuracy in any tests and tests results are not indicative of firm diagnoses.

Tests are ordered as they are able to provide valuable information that, when combined with other information your doctor is able to obtain, will lead to a diagnosis and recommendation of treatment.

Trust in your physician to select and interpret tests

With the wide variety and scope of medical tests, it is unrealistic to undergo all of them. Instead, the selection is best left to a trusted physician to decide on the choice of suitable tests pertaining to your medical problem and the interpretation of the results.

Your doctors should know what can and cannot be revealed by the tests that they are ordering and how the results should relate to your medical condition. It is important to realise that differences in interpretation and treatment may occur between doctors even for the same set of results.

What you need to know before undergoing any tests

Diagnostic tests may be costly and you could run risks of exposure to harmful radiation in some cases. Therefore, you should always discuss with your doctor how the diagnostic tests will be performed, the risks if any, and what will be done following the results.

There may not be a real need to go for a test if the action or treatment remains the same regardless of the test result. Knowing what additional information the test is able to provide and may possibly have any impact on your treatment will determine if the test is necessary.

Here are some questions to ask you doctor before you commit to any tests:

Is it an invasive or non-invasive procedure?
What are the risks and possible complications that could occur from the test
What kind of information are you looking for in this test and the benefits for me?
What is the cost of the particular test being ordered and are there other alternatives?
What are the treatment options after the results are known

Risks vs Benefits

Certain tests, especially invasive ones, do carry risks from infections and bleeding to more serious complications such as heart attacks, etc. Your doctor would make you aware of these risks before making you go for the test.

It is for this reason that your doctor sometime chooses other tests over one that could be more accurate in diagnosing a particular problem. Eg. Coronary angiography is the ‘gold standard’ in diagnosing problems in the coronary arteries or blood vessels but is usually reserved as the last line of test performed.

This is because angiography is expensive, require special equipments and a team of specially trained staff. The risks, while small, are still significantly higher than an non-invasive tomographic scan and accidents in some cases could potentially rupture a usually stable plaque leading to a heart attack.

Also, depending on your medical complaint, your doctor will not subject you to an angiography if he does not suspect you of having coronary artery disease that is causing your chest pains. If your condition is related to your heart’s blood and oxygen supply, a thallium scan may be more useful.

The amount of information provided by a diagnostic test that is able to allow your doctor to devise an appropriate treatment plan for you is considered to be ‘beneficial’. Therefore, you should discuss the ‘risks vs benefits’ of undergoing any procedure with your doctor in order to obtain the best possible outcome.