The result is over diagnosing and over treatment of PEs, thanks to the mainstream medical establishment's rapid, enthusiastic acceptance and massive usage of high tech computed tomography (CT) pulmonary angiography (CTPA) -- without evidence that every clot it revealed was a killer, or even anything worth treating.

Here's the background: CT scans use a contrast dye and x-rays to produce cross-sectional images or "slices" of areas of the body. Introduced in l998, the version of this test called a CTPA was hailed as a super duper new medical tool that could zero in on the pulmonary arteries. That was supposedly a huge diagnostic breakthrough because the test revealed blood clots quickly, allowing doctors to spot pulmonary PEs early so they could be treated before they caused life-threatening problems.

It's important to keep in mind that, like most diseases and conditions, blood clots don't usually come out of the blue and are often related to lifestyle and choices. They are more likely to form in your legs during periods of inactivity, such a long cramped airplane trip (if you don't get up and stretch and walk the aisles frequently), and prolonged bed rest.

Dehydration, joint replacement and other types of surgery, cancer, heart disease, and taking certain drugs such as tamoxifen (to prevent breast cancer recurrence), smoking and obesity also up the risk of these clots which can travel to the lungs causing potentially deadly PEs.

PEs usually produce warning symptoms, including shortness of breath, chest pain, wheezing, light headedness and pallor, which should be treated as an emergency. But expensive CTPA testing rapidly spread into mainstream medical practice as a screening tool to catch PEs, whether there were clear symptoms or not.

They became so popular (and such money-makers) they soon replaced other tests for PE such as ventilation-perfusion scans and pulmonary angiography. In fact, many major medical centers reported their use of the CTPA test had increased seven to 13 times by 2006. Overall, between 2001 and 2006 alone there was a 11-fold rise in CTPA tests ordered for people covered by Medicare.

Because pulmonary emboli can stop your from breathing, go to the heart or brain and kill, improved detection of any PEs had to be a good thing for everyone, right? After all, the medical community assumed using the highly sensitive CTPA test for screening would improve outcomes of this potentially deadly condition by detecting and treating emboli (blood clots) that were previously missed.

Not so fast.

Researchers from Boston University School of Medicine (BUSM) have found that the widespread use of CTPAs led to over-diagnosis and over treatment of this condition. And the consequences are anything but minor.

The BUSM research team investigated the incidence rate, death rate and numbers of treatment complications (including gastrointestinal tract or intracranial bleeding from the use of blood thinners) of PE among US adults before (1993-1998) and after (1998-2006) the introduction of the CTPA test. They found the number of people diagnosed with pulmonary embolism was unchanged before CTPA testing became common. However, the numbers of people diagnosed with PE skyrocketed after CTPA - there was an astounding 81 percent increase in PE cases.

Did people suddenly start to develop more blood clots in their lungs? Not at all. As the new study points out, this "epidemic" of PEs was the result of more emboli being spotted due to more CTPA screening. Finding blood clots sounds like it should always be a good thing, but as so often happens in mainstream medicine, it turns out that assumptions were made about the benefits of this type of screening -- and the dangers of any and all clots -- without looking at the whole picture.

So consider these facts: the BUSM scientists documented that fewer people were dying from PEs even before CTPA was on the scene (8 percent decrease, from 13.2 percent to 12.1 percent). Fatalities dropped even more when CTPA was introduced (36 percent decrease (from 12.1 percent to 7.8 percent).

While that fact in itself would appear to vindicate the widespread use of the test, the PE fatality statistics don't tell the whole story. It turns out there has been a downright dangerous side to massive CTPA screening.

According to the researchers, CTPA detects blood clots that are so small they are clinically insignificant. That means the clots will never cause symptoms or death. Yet these over diagnosed PEs have led to a huge increase in serious complications because of the anticoagulation treatment that's used routinely for PEs.

Before CTPA was a common diagnostic test, the complication rate for emboli was considered stable. But after CTPA was widely used, side effects -- sometimes deadly -- from the use of blood thinners soared by 71 percent.

"Over-diagnosis matters because it can lead to iatrogenic (medical treatment-caused) harm. While a clinically insignificant PE is by definition not harmful, treating such an embolism can cause harm such as bleeding from anticoagulation, which can in the worst case, be fatal," explained lead author Renda Soylemez Wiener, MD, MPH, an assistant professor of medicine at BUSM, in a statement to the media.

"Because the harm of treatment can be substantial, including in the worst case death, it is imperative that we do not turn the problem of under-diagnosis into one of over-diagnosis," the study concluded.

Moreover, the study findings, published in the May 9 issue of the Archives of Internal Medicine warn the ramifications of the widespread use of CTPAs may continue to grow as the use of the test keeps rising.

The scientists are calling for a study to find out what common sense might suggest should have been investigated long ago -- they want a trial randomizing stable patients with small emboli to observation vs. anticoagulation to see if there's any evidence at all that everyone with a PE even requires treatment.

"Better technology allows us to diagnose more emboli, but to minimize harms of over-diagnosis we must learn which ones matter," Dr. Soylemez Wiener stated.

There are other compelling reasons to look at the widespread use of CTPA to consider if using the test for screening is worth additional known dangers associated with the scan, too. For example, the FDA lists possible allergic reactions or even kidney failure due to the contrast agent, or "dye" used in the test. There's also an increased lifetime risk of cancer linked to x-ray radiation exposure from CTPAs.

A study published in the journal Current Opinion in Pulmonary Medicine concluded the radiation dose of CTPA for women undergoing a single 64-slice CTPA procedure increases the risk of breast cancer and lung cancer. For a young 20-year-old woman this would be estimated to increase the relative lifetime risk of breast or lung cancer substantially, up to 5.5 percent.

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