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As I was flipping through the mail the other day, I noticed a flier from my medical clinic offering vascular screening. It warned me that "vascular disease often shows no symptoms or warning signs until it's at an advanced stage and difficult to treat." It encouraged me to call the clinic to schedule three tests — an ultrasound of the belly to look for a bulging aorta, another one for blockages in the carotid arteries to my brain and blood pressure readings to check for leg artery blockages — for an out-of pocket cost of only $150.

The mailing did not encourage me to ask my doctor if I needed these tests. But since I am a primary care physician, I know that as a woman who has never smoked and who has no symptoms of any of these conditions, I should not get these tests.

In fact, the only one of the three supported by evidence is the ultrasound for a bulging aorta — but only for men 65 to 75 years old who smoke or used to smoke.

So what's the harm in getting screened? Isn't an ounce of prevention worth a pound of cure? In some situations, absolutely — for example, screening for colon cancer in older adults or for hypothyroidism in newborns. In these cases, evidence has shown that the benefit of screening a population outweighs the harm. But for many other screening tests, including the ones offered in the flier, the harm outweighs the benefits.

You might wonder how a test like an ultrasound could cause harm. Here's how: If that initial harmless test is abnormal, you may be told that you need another test for follow-up. And so begins the testing cascade, often culminating in an invasive confirmatory test like an angiogram. And if that is positive, surgery might be recommended to fix the problem. Angiograms and surgery can cause kidney failure, strokes, bleeding and even death.

You might be willing to accept these risks if you knew that diagnosing the problem and getting it fixed while you are still feeling fine would lead to longer or improved quality of life. But in many situations, people do just as well or better if they don't do anything until they become symptomatic, and many never become symptomatic.

Let's look at the carotid artery ultrasound as an example. The carotid arteries are the main blood vessels supplying the brain with oxygen and nutrients. Significant blockage of a carotid artery can cause a stroke, and these blockages can be seen on an ultrasound and fixed with surgery. And if you have experienced transient strokelike symptoms, known as TIAs, this surgery could prevent a stroke.

But if you haven't had those symptoms, there is good evidence that the surgery itself causes more complications — including strokes, deaths and heart attacks — than it prevents. There are safer ways to prevent strokes for people at risk that don't require ultrasounds, angiograms or surgery, such as medications for high blood pressure and high cholesterol, smoking cessation and, in certain cases, daily aspirin.

So why is my clinic encouraging me to get useless tests that will cost me money and might cause me harm? Because economic pressures in health care are creating intense competition and the need to generate new streams of revenue. We must insist, however, that our health care organizations do not respond to these pressures by promoting dubious programs such as direct-to-consumer marketing of unnecessary and potentially harmful screening tests.

The health and well-being of Minnesota residents should not be a pawn in a game of organizational survival.

(A good place to get unbiased, easy-to-understand, evidence-based information on screening tests is the U.S. Preventive Services Task Force website at http://www.uspreventiveservicestaskforce.org.)

Hanna E. Bloomfield is a physician in St. Louis Park.