Another problem with diagnostic tests is that they often lead to unnecessary medical procedures, even surgery. In 1978 the US Office of Technology Assessment estimated that only 10% to 20% of medical procedures were of proven value to patients. As much as 80% to 90% of treatments may make good medical sense but are without scientific proof. It has been estimated that up to 30% of the value of most treatments is due to its placebo effect. (A placebo is a pharmaceutically empty pill or medical procedure that patients believe is an effective cure but actually isn't.) In other words many people with certain health conditions get better even when they receive dummy treatments if they along with their physician believe in its effectiveness. Medical archives are replete with examples of treatments that cured patients at the time only to be proven ineffective later on. For example, several early treatments for herpes infections had positive results in 85% of the patients even though later studies found these treatments to be ineffective. It is possible that the "belief" in some tests, procedures, or treatments is more important than the procedure itself. Some experts suggest that because the placebo effect can heal, patients should demand less invasive remedies and be less eager to accept risky experimental procedures. This is one reason many people are becoming interested in non medical alternative healing methods.

Thus when you go for a physical examination, you can help determine which tests you are willing to be subjected to by asking the right questions:

What do you expect to find? You should start by asking why you need the test. How will it help facilitate a diagnosis? You need to ask about alternatives and the disadvantage of waiting and not testing. Sometimes the best test is the test of time. Agreeing to a test because it is routine procedure is not a satisfactory explanation.

What risks are associated with the test? No test is risk free; therefore you should compare potential benefits and risks.

One problem with tests is that they are not 100% accurate. An inaccurate result can lead to a wrong diagnosis. A false positive may occur in which a test incorrectly reveals an abnormality. That is, a test shows "positive"-a disease exists-when it really isn't present. This often provokes needless anxiety, causing some people to feel and even act sick. Conversely, normal results do not necessarily indicate good health. False negatives may occur in which test results indicate normality even though a person is sick. That is, a test shows "negative"-no disease exists-when it is actually present. These results may lead to a false sense of health and may delay much needed treatment at critical stages of a disease.

Statistically, test results are accurate for about 95% of the population. Thus 5% of patients can be expected to have a false positive or false negative on any laboratory test. Other factors that may cause test errors include certain medications, exercise, stress, eating, time of day, and mistakes in handling or processing specimens.

Another problem with tests is that they may be associated with physical risks. Some of the more common risks are infection, bleeding, damage to vital structures, and reactions to anesthetics, drugs, and dye-contrast materials.

What are the options after the test? If a test is positive, then what? If none of the options is plausible to you, why have the test administered? If it is impossible to treat a disease that a test reveals, the test is not justified. The diagnosis of treatable diseases, on the other hand, usually justifies the test.