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Having a battery of medical tests may seem like a good idea — it seems as though your doctor is leaving no stone unturned in the quest for hidden disease. And getting the right test at the right time can be lifesaving.

But undergoing testing that you don’t need not only is a waste of time and money but also can cause harm. “It can expose you to radiation, cause unnecessary anxiety and lead to expensive follow-up tests and treatments that themselves carry risks, sometimes even more so than the disease you’re screening for,” says Tanveer Mir, chair of the Board of Regents of the American College of Physicians.

Here are five examples of common tests that are done more often than necessary.

Stress tests for heart disease

Why you usually don’t need one: Many people get the test — also called a treadmill or exercise test — as part of their routine checkup. But if you’re at low risk, the tests, which involve having you walk on a treadmill while connected to an electrocardiogram to measure your heart health, aren’t recommended. And they can produce misleading results that may require further testing, says Mark Creager, president of the American Heart Association and director of the Heart and Vascular Center at the Dartmouth Hitchcock Medical Center in Hanover, N.H.

When it’s warranted: An exercise stress test may be necessary if you have symptoms of heart disease, such as chest pain or shortness of breath, or if your doctor determines that you’re at increased risk of a heart attack because of high blood pressure or cholesterol levels, diabetes, smoking or other risk factors.

Chest X-rays before surgery

Why you usually don’t need one: Many hospitals routinely order pre-surgery X-rays. But for low-risk patients, those tests find something that requires your surgeon or anesthesiologist to change your care only about 2 percent of the time, according to a study published last year in JAMA Internal Medicine. In most cases, a medical history and physical exam will give your doctors all of the information they need.

When it’s warranted: A chest X-ray before surgery is necessary if you have a history of heart or lung disease, or symptoms of those conditions. You should also have a chest X-ray if you’re older than 70 and haven’t had one in the past six months or if you’re having surgery on your heart, lungs or any other part of your chest.

CT scans for headaches and concussions

Why you usually don’t need one: If you’re suffering from a bad headache or you hit your head hard, getting a CT scan — which combines multiple X-ray images to create 3-D images — may seem to make sense. But the test is often not needed.

In fact, 1 in 3 CT scans for minor head injuries aren’t useful, according to a 2015 study. “Concussions can’t be seen on a CT scan,” explains the lead author, Edward Melnick, an assistant professor of emergency medicine at Yale University.

In addition, 1 in 8 visits to a doctor for a headache or migraine leads to a CT or MRI scan, according to a 2014 study from the University of Michigan’s medical school. But even for people with recurring headaches, only 1 to 3 percent of scans finds a significant abnormality.

When it’s warranted: In most cases, a neurological exam that includes questions about the injury and symptoms can determine whether you or your child has had a concussion. Expect a CT scan only after a car crash, a fall from a bike when you’re not wearing a helmet, or another serious accident, or if you have worrisome symptoms, such as confusion, loss of consciousness, weakness or tingling on one side of the body or loss of hearing or vision.

For headaches, imaging tests may be appropriate if you have unusual symptoms or an abnormal neurological exam or if your doctor can’t diagnose the problem based on your symptoms.

Carotid artery ultrasounds

Why you usually don’t need one: Pitched as a simple, painless way to assess your risk of a stroke, the test checks for clogging in the carotid arteries, which are on either side of your neck. But among people who don’t have any symptoms, fewer than 2 percent of those who have blockages of those arteries end up having a stroke.

The test doesn’t expose people to radiation, but it often suggests that they have a blockage when in fact they don’t, according to a 2014 review in Annals of Internal Medicine.

When it’s warranted: The benefits of the test outweigh the risks if you have a history of stroke or mini-stroke (also known as a transient ischemic attack), which is often marked by sudden numbness or weakness on one side of the face or difficulty speaking or understanding.

Pelvic exams for women

Why you usually don’t need one: There’s no good evidence that pelvic exams help detect ovarian cancer or allow doctors to ease benign problems such as fibroids or cysts by treating them earlier, according to a 2015 review in JAMA Internal Medicine. On the other hand, they can make women feel uncomfortable and anxious — and slightly increase the risk of unnecessary surgery. For that reason, the American College of Physicians no longer recommends routine pelvic exams.

When it’s warranted: A pelvic exam may be necessary if you’re experiencing possible warning signs of ovarian cancer, fibroids or cysts, such as unusual vaginal discharge, abnormal bleeding, persistent bloating, pelvic pain, discomfort during sex or urinary problems such as leakage or incontinence. Even if you don’t need a full pelvic exam, most women do need to undergo routine screening for cervical cancer.

Copyright 2016. Consumers Union of United States Inc.

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