Can these ultrasound tests save your life?
You may already have seen one of the offers on TV or gotten a brochure in the mail.
They're pretty hard-sell, designed to unnerve you. "We can help you AVOID A STROKE in just 10 minutes,"
one brochure says. The cover letter may be signed by a
celebrity, like Peggy Fleming. You're offered "high-quality ultrasound screenings" in a
nearby location for a special reduced price.
If you choose three different tests (for example, for stroke,
abdominal aortic aneurysm, and hardening of the arteries), you
can save a bundle. And more important, according to the testimonials in the ads,
you can save your own life. They don't mention
that insurance seldom pays for this voluntary testing, which costs
up to $300 for the whole package. Still, this may sound like a
good deal -- but maybe it's not.
The ultrasound tests you'll be urged to get are painless and
quick -- the sound waves are safe and there's no radiation, unlike
CT scans. They are legitimate tests, used by doctors and hospitals.
The usual offerings in such packages are these:
- Carotid artery screening. These two large arteries in the neck
supply blood to the brain. Significant blockage, which can be
detected by ultrasound, puts you at increased risk for a stroke.
- Abdominal aortic aneurysm screening. The abdominal portion
of the aorta is the large vessel that supplies blood to the
abdomen, pelvis, and legs. An aneurysm is a weakening and ballooning
in the artery wall. A ruptured aorta is almost always fatal.
Ultrasound can detect aneurysms, and surgery can correct them,
- Peripheral arterial disease screening. Blockage of the arteries
in your legs may indicate that your coronary arteries are also
blocked, and that you are at risk for a heart attack.
- Bone ultrasound. Used to detect bone loss, this is an alternative
to the standard DEXA (dual-energy X-ray absorptiometry)
scan, which uses low-dose X-rays to evaluate bone density. Ultrasound
is not as accurate, but it's cheaper and involves no radiation.
So what could be wrong with this offer?
A lot. We advise against such screenings, for these reasons:
- The false-alarm factor: One drawback of any diagnostic test
is false-positives -- that is, the test suggests there is disease when,
in fact, there is none. When low-risk people are screened, the odds
that a positive result will turn out to be false increase dramatically.
For this reason these tests are usually reserved for people with risk
factors or actual symptoms.
If an ultrasound screening test shows that you have the disease,
you'll have to undergo further tests, such as angiography -- an
invasive and expensive test that has risks of its own, including a
very small risk for stroke. The biggest drawback is that the whole
process may simply have been unnecessary. This is only one example
of why screening low-risk people can do more harm than good.
- The false-assurance factor: Quick tests can fail to discover
real problems -- that is, they can produce false-negatives. In that
case, they can confer a false sense of security.
- The money factor: Though it might seem that a few hundred
dollars is reasonable, it's likely to be money wasted. Also, companies
offering "bargain" tests often urge you to repeat the tests,
sometimes yearly -- a big additional expense. In contrast, if you do
need screening because of risk factors and have a referral from a
doctor, your medical insurance (for example. Medicare) will
cover the cost.
- The quality factor: The tests may not be high-quality or
carefully administered by licensed sonographers. Results may be
reviewed in a hurry or by unqualified technicians. Some centers
take time to talk about results, others simply hand out reports with
no explanations. The FDA has approved these ultrasound tests for
people with symptoms, but not for general screening. There's no
required inspection or supervision of these centers.
- The emotional factor: A round of follow-up tests that turn out
to be needless can cause weeks of worry. Even if some small
problem is detected, the right course of action may be hard to
determine. Some incidental finding may cause you months or
years of anxiety and then turn out to be nothing.
What the Task Force says
The U.S. Preventive Services Task Force is an expert panel that
evaluates screening tests in order to protect the public and con-
serve medical resources. Here's what it says about the kinds of
tests being offered in these packages:
Bottom line: Before you get any test, get medical advice. If
you're under 60, you don't need these tests, unless you have
symptoms or risk factors. In that case, you should see a doctor rather
than referring yourself to some center. These "packages" promise
a lot, but deliver little in the way of benefits. They can, however,
deliver anxiety and even suffering, instead of the "peace of
mind" they promise. The pitch advises you to take charge of your
health care. We urge you to do that by saying no to these offers.
- Carotid artery screening: Recommended only if there are
symptoms. A doctor may think this test worthwhile in people over
60 who smoke, are obese, or have high blood pressure or other
risk factors for stroke.
- Abdominal aortic aneurysm screening: Might be useful
in men over 60, especially smokers, or those with high blood
pressure and/or a family history of aortic aneurysm.
- Peripheral arterial disease screening: Recommended
only for people with symptoms (for example, numbness in the legs).
- Osteoporosis screening: Recommended only for women
65 and older (and for younger women with risk factors, such as
family history). DEXA scans are more accurate than ultrasound.
This is reprinted from the UC Berkeley Wellness Letter from March, 2005.
I agree with their recommendations. I do think that men who smoke or have high blood pressure
should have an abdominal ultrasound around age 60 to look for an abdominal aortic aneurysm
(though your insurance may not cover the cost of this test if done as a screening test). I am not in favor
of general screening for carotid artery narrowing, as I think the data regarding
the benefits of surgery in people without symptoms of TIA or stroke is unclear.
Bone density tests are routinely offerred in this practice to women over age 65, and
to some younger women with certain risk factors for osteoporosis. The best simple
screening test for peripheral artery disease is examination of the feet for
temperature and pulses (done in this practice routinely).