Pulmonary Embolism Diagnosis

A comprehensive overview of pulmonary embolism covering subjects as: treatment, symptoms, diagnostics, research, causes, pictures and images
Pulmonary Embolism Diagnosis

Pulmonary embolism diagnosis

     Pulmonary embolism diagnosis is based on clear identification of risk factors, of deep vein thrombophlebitis, of signs and symptoms and imaging tests (venous Doppler ultrasound, echocardiography, chest radiography, computed tomography, CT, MRI, pulmonary angiography, lung scintigraphy), ECG- ECG determination (PDF of fibrin degradation products) or D-dimers in blood.

Pulmonary scintigraphy

     Is administered IV or albumin microspheres labeled Y. They arrive in the pulmonary capillaries and fix preferential in areas with good perfusion. A Y camera is used to scan the lungs in different incidents detecting segmental perfusion defects. A separate ventilation examination can determine if the perfusion defect corresponds to an athelectasy. Perfusion scintigraphy can give false results in case of chronic pulmonary disease, pulmonary edema or pleural exudates. Regarding the probability of pulmonary embolism scans are graded as: normal, low (<20%), intermediate or high (> 80%), depending on the number and size of the observed infusion defects.

     Infusion scintigraphy must be interpreted in clinical context, when a pulmonary embolism is suspected. A careful and proper medical history and clinical examination but with a low probability scan for pulmonary embolism may correspond to the pulmonary embolism diagnosis in 40% of cases.

Pulmonary angiography

     This is an invasive diagnostic method performed by catheterization of the straight cavities and placing a catheter in each pulmonary artery. Although it involves the risk of intervention in the right cavities and hypotension to the contrast substance it has some advantages over other diagnostic methods, namely: to allow measurement of pulmonary artery pressure, help to differentiate secondary pulmonary hypertension of pulmonary embolism to pulmonary primitive hypertension, allows mechanical fragmentation of thrombus present in the pulmonary artery. Occlusions of the vascular branches can be observed or intraventricular filling defects in acute pulmonary embolism, in the chronic disease revealing the artery dilatation with small distal vessels. It requires a very precise knowledge of the pulmonary circulation to detect small pulmonary embolisms.

Pulmonary CT or the contrast substance

     It is a new pulmonary embolism diagnosis method, non-invasive, the technique involving peripheral injection of contrast substance quickly followed by a spiral CT lung scan. It is useful to detect proximal pulmonary embolism because the small peripheral embolism can be omitted.

Pulmonary MRI

     It allows the detection of pulmonary embolism without using the contrast substance. It requires a vast experience of the examiner and it is not a first line method of diagnosis.

     Diagnosis of pulmonary embolism is difficult because symptoms can be attributed to other causes such as heart attacks or panic.

     Correct diagnosis is based on a well-performed history and the exclusion of other diseases.

     The doctor should be informed about the symptoms and other risk factors such as history and physiological hypercoagulability or recent surgery. This information, combined with a well done exam, can lead to finding the best solutions for diagnosis of deep vein thrombosis or pulmonary embolism.

     The tests which are performed if the patient accuses the absence of air (dyspnea) or stabbing chest are:

  • Chest radiography: its outcome removes the suspicion of dilated heart or lung injury, leading to other examinations
  • Electrocardiogram (ECG) follows the electrical activity of the heart and can exclude a possible heart attack
  • Blood gas measurements: rapid decrease of oxygen level may suggest a pulmonary embolism.

     The results of these initial tests may rule out other causes such as heart attack and pneumonia.

     The tests made for pulmonary embolism diagnosis are:

  • D-dimer measurement: this is a test that measures a substance that is released when the thrombus is off; usually in patients with pulmonary embolism the D-dimer level is increased
  • CT scan: is often used to diagnose pulmonary embolism
  • Perfusion lung scan: This test detects an abnormal blood flow in the lungs after intravenous injection of a tracer and inspired a radioactive gas
  • Pulmonary angiogram: is the surest way of diagnosing a pulmonary embolism, it is not available in smaller hospitals and is more invasive than other methods of diagnosis
  • Echocardiogram: This test detects abnormalities of right ventricular size and function, which may be due to pulmonary embolism
  • Doppler ultrasound: uses reflected waves to determine the presence of a thrombus in a vein of the lower limb
  • Magnetic resonance imaging (MRI) may be useful in detecting thrombus in deep veins and lungs.