5 medical tests that could save your life (and 5 to skip)

These days, doctors are offering all sorts of screening and diagnostic tests. Some are proven to save lives - others, not so much. And inappropriate testing does more than waste your time and money. It can cause anxiety and necessitate additional, follow-up tests - which sometimes lead to needless surgery.

To protect yourself, Dr. Orly Avitzur says it's important to ask your doctor about the medical evidence behind each test he/she recommends. Keep clicking as Dr. Avitzur, medical advisor at Consumer Reports, reveals five tests that you should consider getting - and five you should avoid at all costs.

Full-body CT scan

Skip it. Full-body computed-tomography (CT) scans, which can cost $1,000, have been touted as a way to detect early signs of cancer and heart disease. But if you're healthy, they're of no proven benefit. The American College of Radiology warns that they can lead to costly and potentially risky follow-up exams to check out harmless abnormalities that otherwise would have gone undetected.

And then there's the risk of radiation. "The average radiation dose from medical imaging has increased more than six-fold over the last 30 years, with CT scans being the largest contributor," says Dr. David J. Brenner, director of the Center for Radiological Research at Columbia University. "We've found that full body CT scans expose patients to far more radiation than conventional plain film X-rays and consequently a higher lifetime risk of cancer deaths, about one in 1,250 for a 45-year-old adult and one in 1,700 for a 65-year-old adult," he said.

Screening tests for heart disease

Skip it. Feeling fine, but your doctor is recommending an electrocardiogram (ECG) or exercise stress test? If you don't have any heart risks, it's probably best to take a pass.

The American College of Preventive Medicine does not recommend routine screening of adults using ECG, stress testing, or the blood test for C-reactive protein, a marker for inflammation.

To find whether you should have a particular cardiovascular screening test, depending on your risk category, age and gender, check out this tool.

Sleep apnea testing

Get it. Loud snoring, choking or gasping for air in your sleep, and suffering from morning headaches or daytime sleepiness are symptoms of obstructive sleep apnea - a potentially dangerous sleep disorder that affects up to one in four men and one in 10 women (including many who are overweight). Besides affecting your quality of sleep, apnea can trigger the release of stress hormones that elevate heart rate and raise your risk for high blood pressure, heart attack, stroke, and type 2 diabetes.

Problem is, fewer than 15 percent of apnea sufferers know they have the disorder. If you fail to mention your symptoms to your doctors, they may not ask about it during your routine exams. An overnight sleep study called a polysomnogram can determine if you have it, and allow you to start treatment.

Automated nerve testing

Skip it. Some doctors use hand-held "nerve conduction" devices to check for nerve damage caused by diabetes, pinched nerves, and other ailments. But Dr. John D. England, a neuromuscular specialist at Louisiana State University School of Medicine, says that if testing using one of these automated devices is suggested, it's best to politely refuse. Instead, he says, ask that electromyography/nerve conduction studies be performed by a doctor - typically a neurologist or physiatrist - with training in electrodiagnostic medicine. "Several well-controlled studies have demonstrated that the automated nerve conduction tests have poor diagnostic accuracy," he said, adding that the patient risks receiving an incorrect diagnosis, which could lead to needless and risky surgery.

Virtual colonoscopy

Skip it. Colonoscopy can spot colon cancer at its earliest stages, when it's still treatable. But because some people think conventional colonoscopy - in which the doctor looks for tumors or polyps with a long, flexible viewing scope inserted into the rectum - is too unpleasant, they opt for so-called virtual colonoscopy. That's a procedure in which the colon is inspected not visually but with computed tomography (CT) scans.

But virtual colonoscopy, a.k.a. CT colonography, requires the same preparation as conventional colonoscopy - taking laxatives to clean out the colon. And if virtual colonoscopy does turn up a polyp, odds are you'll need to follow up with a conventional colonoscopy, says Dr. Mark B. Pochapin, director of the Jay Monahan Center for Gastrointestinal Health. And then there's the matter of radiation exposure. Unlike conventional colonoscopy, CT colonography exposes the body to cancer-causing X-rays.

Blood pressure check

Get it. One in three adults in the U.S. has high blood pressure, a leading cause of heart attack, heart failure, stroke, kidney trouble, and vision loss. But since high blood pressure typically causes no obvious symptoms, up to one in five people who have the problem don't know they do. The key to detection is having your blood pressure tested.

The American Heart Association recommends checking it at least once every two years - but Dr. Avitzur says it might be better to do so annually, especially if high blood pressure runs in your family.

Mammogram

Get it. Mammography can detect breast cancer in its early stages - well before a lump is big enough to be felt. Health experts recommend annual mammograms - but for whom, and how often? The American Cancer Society recommends annual screening mammograms for all women beginning at age 40. The U.S. Preventive Services Task Force revised its guidelines in 2009 to recommend screening mammography for women aged 50 to 74 years every other year and against screening women in their 40's of average risk.

Given the conflicting guidelines, it's hard to know what to do. If you're a healthy woman in your 40's, ask your doctor about whether mammography is right for you.

Screening for stroke

Skip it. Blockages in the carotid arteries in the neck can lead to stroke, and some doctors use ultrasound testing to look for those blockages. But the U.S. Preventive Services Task Force recommends against routine screening for these blockages in the general population. So does the American College of Preventive Medicine.

The test can generate both false-positive and false-negative results - which can lead to needless additional testing or risky surgery. Addressing other risk factors for stroke - like high blood pressure, high cholesterol levels, and smoking - is a better way to reduce your chances of having a stroke, Dr. Avitzur says.

Cholesterol testing

Get it. It's no secret that cholesterol that builds up in the blood vessels of the heart can trigger a heart attack - and the higher your level of low-density lipoprotein (LDL) cholesterol, the greater your risk. But high cholesterol causes no symptoms, so the only way you can find out you have it is to have it checked via a simple blood test.

If you're a man over the age of 35, or a woman who's 45 or older who smokes, has high blood pressure or diabetes, or has other risk factors for coronary artery disease, U.S. Preventive Services Task Force strongly recommends cholesterol screening.

Pap smear

Get it. Pap smear testing is strongly recommended for women age 65 or under who are sexually active and whose cervix is intact. But the U.S. Preventive Services Task Force cautions against routine pap screening for women over 65, those who have had recent screening with normal Pap smears and are not otherwise at high risk for cervical cancer, and those who have undergone total hysterectomy for conditions other than cancer.

Cervical cancer rates have fallen in recent decades, but cervical cancer remains the 10th-leading cause of cancer death in the U.S. Sadly, about 60 percent of women with invasive cervical cancer have not undergone a Pap test in the five years prior to their diagnosis.