Pulmonary embolism (or "PE") is the blockage of the main artery of the lung. It is often a result of a blockage in the leg (deep vein thrombosis, DVT) which travels through the blood to the lung.
Pulmonary embolism and DVT are two manifestations of venous thromboembolism which has a reported annual incidence of 100-300 per 100,000 in Western countries. It is ranked as the third most prevalent cardiovascular disorder. Incidence is equal between men and women. Incidence is higher in women of child-bearing age due to the associated risk of pulmonary embolism with pregnancy and with some birth control medications, but it is higher in older men compared to older women. Incidence increases with age, from a rate of 5 per 100,000 in childhood to 500-600 per 100,000 in individuals 75> years of age.
Pulmonary embolism may result in irreversible damage to the affected lung, reduced oxygen in the blood, organ damage due to lack of oxygen, or in the case of a large clot, death may occur. It is estimated that only 1 in 5 individuals suspected to have pulmonary embolism have the diagnosis confirmed.
Diagnosis is complicated as the presentation of pulmonary embolism varies from no symptoms to cardiogenic shock. If symptoms do occur they may include chest pain, shortness of breath or coughing up blood. Blood clot symptoms in the leg include swelling, pain, tenderness or redness of the affected location.
Diagnosis is based on clinical symptoms and laboratory tests (e.g. D-dimer test) and imaging (e.g. Computed tomographic pulmonary angiography (CTPA)). CTPA is becoming the standard of care to evaluate subjects with suspected pulmonary embolism. Treatment usually includes anticoagulant medication.
In a study published in May of 2011, researchers analyzed the Nationwide Inpatient Sample and Multiple Cause-of-Death databases and compared incidence, mortality and complications of pulmonary embolism in the United States. Data was analyzed prior to (1993-1998) and after CTPA introduction (1998 to 2006). After the introduction of CTPA, the incidence of pulmonary embolism increased from 62.1 per 100,000 to 112.3 per 100,000. Mortality from pulmonary embolism has been steadily decreasing in recent years. From 1993 to 1998, mortality rates dropped from 13.4 to 12.3 per 100,000 and reduced to 11.9 per 100,000 after the introduction of CTPA. CTPA has led to the identification of more emboli, however, this has also led to over diagnosis of pulmonary embolism and unnecessary treatment. Further, complication rates due to the use of anticoagulants increased by 71% after introduction of CTPA. However, if left untreated, pulmonary embolism can have a mortality rate as high as 25%.Misdiagnosis of a Pulmonary Embolism
The sobering truth of PE cases is that the majority of patients who die from pulmonary embolism are patients who are never treated for pulmonary embolism.
There is no question that a pulmonary embolism can sometimes be tough to diagnose. Doctors have a lot of sometimes confounding variables to consider in figuring out the cause of the patient's difficulties. In some cases, a doctor can miss a pulmonary embolism and still render reasonable treatment consistent with the standard of care.
But, too often, patients with shortness of breath and obvious risk factors for PE that read like a billboard end up with a diagnosis of panic attack, anxiety, or something else less serious.
That seems to be the problem, really, with many misdiagnosis cases. Doctors fail to rule out the more serious of the potential problems and then arrive at the less serious diagnosis. It is easier. It takes time and energy to take the appropriate steps to rule out more serious life threatening problems. A chest x-ray might help a doctor rule out pulmonary embolism because there are no changes in the blood vessel patterns after embolism and signs of pulmonary infarction. So might a blood test, an electrocardiogram, d-dimer, and ultrasound, pulmonary angiography, lung perfusion scan, or a CT angiogram. Sometimes the easy answer, "Oh, she's anxious and hyperventilating, there is no need to look any further" leads to medical malpractice failure to properly diagnose lawsuits.
A study published in the Archives of Internal Medicine (2000), explored physicians' attitudes toward the misdiagnosis of pulmonary embolism and treatment of patients. The results of the study indicated that physicians may provide treatment for pulmonary embolism without confirmation of an embolus rather than take a chance in missing a case of pulmonary embolism.
Sometimes doctors don't appreciate the significance of the risk factor they ignore. The main reasons for misdiagnosis of pulmonary embolism include low awareness of risk factors by physicians, variability in patient symptoms, misinterpretation of tests, and atypical clinical manifestations. Radiologists must ensure the quality of the CTPA study and if pulmonary embolism is actually present. Any uncertainty should be stated as such and additional imaging should be requested if appropriate.
Another study published in 2009 evaluated the use of diagnostic flow-charts used in the management of pulmonary embolism, pointing to its potential in misdiagnosis. The authors commented on the complexity of the algorithm which includes several consecutive tests. The algorithm states that chest X-rays found to be normal are generally followed by ventilation perfusion (V/Q). Where non-high V/Q is reported, patients should receive a CTPA. The study found that this algorithm was only used properly in 74% of patients studied. Misuse of the algorithm may lead to delay in establishing or excluding pulmonary embolism, delays in treatment or unnecessary treatment.
Here is a simpler statistics that puts the PE misdiagnosis problem in even better context. Approximately 21 percent of otherwise healthy young people with pleuritic chest pain -- sudden sharp, stabbing, burning or dull pain -- without no known risk factors for pulmonary embolism that present to an emergency department just with onlythat type of pain in fact have a pulmonary embolism. With a greater than 1 in 5 chance, you really want to rule out a PE, right?