What is Pulmonary Embolism?
To summarize from the main pulmonary embolism article, pulmonary embolism happens when an artery or one of its branches in the lung is blocked. This blockage is usually caused by a blood clot that has traveled from another part of the body through the bloodstream, usually a leg (deep vein thrombosis or venous thromboembolism or DVT). Fat, air, or amniotic fluid can also cause a blockage.
When the blood flow through the lungs is obstructed, pressure is put on the right ventricle of the heart which is when symptoms such as shortness of breath and chest pain will start to appear.
As with many conditions, doctors have been looking for ways to anticipate whether or not a patient has a certain set of risk factors that could result in pulmonary embolism. Some patients may be more susceptible than others. This would aid emergency room and family physicians decide whether further, more-invasive diagnostic tests are required.
In many cases, "pre-diagnosing" patients according to certain protocols has led to a diagnosis when other methods (CT scans or X-rays) tested negative. Investigators into alternative diagnostic protocols have found that 90% of blood tests and ultrafast CT scans used to diagnose pulmonary embolism come back negative.
Doctors and patients have become to rely on X-rays, CT scans, etc. to do the diagnosing. It is important to remember that sometimes a good discussion with your doctor about underlying factors will help him decide the next phase of diagnosis.
Establishing new diagnostic protocols have helped to lower overall costs to the health care system and to patients. A CT scan, for example, can cost up to $2,500.
Types of Pre-X-ray Diagnosis Protocols
There are three methods commonly used by doctors to assess whether or not a patient is a low-, medium-, or high-risk for blood clots and pulmonary embolism.
Pulmonary Embolism Rule-Out Criteria (PERC rule)
This set of criteria is used when a physician has already determined that a patient is at low-risk.