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Thromboembolism Workup

  • Author: Vera A De Palo, MD; Chief Editor: Harris Gellman, MD  more...
Updated: Nov 25, 2015

Laboratory Studies

The arterial blood gas on room air demonstrates hypoxemia (PaO2 < 80 mm Hg) and an elevated alveolar-arterial oxygen gradient. Acid-base status may demonstrate a respiratory alkalosis.

Enzyme-linked immunoassay (ELISA) can be used to quantify the presence of D-dimer, which is a specific degradation product of cross-linked fibrin.[20] This is an important marker of the activation of fibrinolysis. It can be elevated in pneumonia, cancer, sepsis, and surgery.

A plasma D-dimer level of higher than 500 ng/mL has been shown to have a sensitivity of 97% and a specificity of 45%. The value of D-dimer is in its negative predictive value. A plasma D-dimer level of less than 500 ng/mL essentially excludes PE.

Elevated troponins are associated with adverse prognosis in acute PE.[21] Elevated natriuretic peptides, brain natriuretic peptide (BNP), and N-terminal pro-BNP have been shown to be predictive of adverse short-term outcomes in acute PE and can be predictive of mortality.[22, 23] Measurement of both troponin and BNP are important for risk stratification in patients with PE.


Chest Radiography

Chest radiographic findings most often are normal. Radiographs may, however, reveal an enlarged right descending pulmonary artery, decreased pulmonary vascularity (Westermark sign), a wedge-shaped infiltrate, or an elevation of the hemidiaphragm (Hampton hump). If infarction occurs, a pleural effusion may be present.


Helical (Spiral) Computed Tomography

Helical (spiral) computed tomography (CT) allows for the imaging of pulmonary vessels by way of intravenous contrast material as the patient moves through a gantry at a constant rate and the radiography source rotates. PE is diagnosed by filling defects, which are either central or adherent to the wall. The CT scan below shows a filling defect.

Helical CT scan of the pulmonary arteries. A filli Helical CT scan of the pulmonary arteries. A filling defect in the right pulmonary artery is present, consistent with a pulmonary embolism.

The advantage of helical CT scanning is that it is minimally invasive and allows concurrent visualization of the parenchyma, pleura, and mediastinum. When looking at the main, lobar, and segmental veins, the sensitivity of helical scanning is about 93%. Its positive predictive value is approximately 95%.

The limitations of helical CT scanning include the need for contrast and for a higher dose of radiation than that required by some other diagnostic modalities. Obliquely or horizontally oriented vessels like those of the segmental branches of the right middle lobe and lingula are poorly visualized. The scan is technically inadequate or inconclusive in approximately 1-10% of the cases.


Doppler Ultrasonography

Results from Doppler ultrasonography can indicate the presence of thrombus within a vein. A normal vein is free of internal echoes and can be compressed. In acute DVT, however, internal echoes are present and the vessel is not compressible.

Duplex scanning of the venous system uses Doppler flow assessment combined with B-mode ultrasonography. The advantage of color flow Doppler ultrasonography is the ability to determine motion and the direction of flow.



Echocardiography can demonstrate signs of right-sided heart strain. Right ventricular dilatation, right ventricular hypokinesis, or tricuspid regurgitation may be present. Interventricular septum bulging into the left ventricle may be present, and the size of the left ventricle may be reduced. Echocardiography can also be used to identify signs of impending heart failure.


Pulmonary Angiography

Pulmonary angiography has long been the diagnostic criterion standard. Angiography allows for the visualization of the pulmonary vasculature using contrast material, and in the event of PE, it evidences the cutoff of a vein and a lack of flow to the affected area.

It is an invasive procedure that requires the administration of intravenous contrast material, and it is more expensive than other procedures.

Pulmonary angiography leads to increased morbidity in approximately 2-5% of patients; this is related to bleeding and to complications from the use of intravenous contrast material. Mortality occurs in less than 1% of patients in whom this procedure is performed.



Contrast venography is an invasive technique that can provide direct proof of thrombus by demonstrating a filling defect with the aid of contrast medium through the deep venous system. However, it can cause iatrogenic venous thrombosis, tissue sloughing from contrast extravasation, and an allergic contrast reaction.


Ventilation-Perfusion Scanning

Ventilation-perfusion scanning is a common screening technique. This modality provides a probability estimate for PE by evaluation of the size and the number of defects in the perfusion of the lung compared with the areas of ventilation.

The diagnosis of PE is easily made with this modality when the probability estimate is high for PE. With a normal scan finding, the possibility of PE is excluded. However, the test results are nondiagnostic in about 66% of cases. The image below compares normal ventilation findings with a perfusion defect.

Ventilation-perfusion scan. Left image: Posterior Ventilation-perfusion scan. Left image: Posterior view of normal findings on ventilation scan. Right image: Posterior view of a perfusion scan that reveals a perfusion defect in the left upper quadrant. The defect in the middle of the image is due to the position of the heart.


Impedance plethysmography may detect impaired venous emptying of the leg by assessing the volume response to temporary occlusion of the venous system. Emptying is assessed by the rapidity of volume decrease. Slow emptying indicates obstruction.

Impedance plethysmography is a noninvasive method of assessment. Sensitivity and specificity have been reported to be between 92% and 95%. However, it is of limited value when DVT is asymptomatic or distal or when findings are nonocclusive.

Conditions leading to poor forward blood flow, hypotension, or vein compression can be responsible for false-positive results.



Electrocardiography is of greatest value in ruling out myocardial infarction. Sinus tachycardia often is present, and right axis deviation, right bundle branch block, and deeply inverted T waves in V1 -V3 may be found. An S1 Q3 T3 pattern may be seen.

Contributor Information and Disclosures

Vera A De Palo, MD Associate Professor, Department of Medicine, The Warren Alpert Medical School of Brown University; Associate Chief of Medicine, Memorial Hospital of Rhode Island

Vera A De Palo, MD is a member of the following medical societies: American College of Chest Physicians, American College of Physicians, American Medical Association, American Thoracic Society, Rhode Island Medical Society, Society of Critical Care Medicine

Disclosure: Nothing to disclose.


Abdallah E Kharnaf, MD Resident Physician, Department of Medicine, Memorial Hospital of Rhode Island, The Warren Alpert Medical School of Brown University

Abdallah E Kharnaf, MD is a member of the following medical societies: American College of Physicians

Disclosure: Nothing to disclose.

Chief Editor

Harris Gellman, MD Consulting Surgeon, Broward Hand Center; Voluntary Clinical Professor of Orthopedic Surgery and Plastic Surgery, Departments of Orthopedic Surgery and Surgery, University of Miami, Leonard M Miller School of Medicine, Clinical Professor, Surgery, Nova Southeastern School of Medicine

Harris Gellman, MD is a member of the following medical societies: American Academy of Medical Acupuncture, American Academy of Orthopaedic Surgeons, American Orthopaedic Association, American Society for Surgery of the Hand, Arkansas Medical Society

Disclosure: Nothing to disclose.


Michael J Belanger, MD Clinical Instructor, Department of Orthopedics, Harvard Medical School

Disclosure: Nothing to disclose.

Jegan Krishnan, MBBS, FRACS, PhD Professor, Chair, Department of Orthopedic Surgery, Flinders University of South Australia; Senior Clinical Director of Orthopedic Surgery, Repatriation General Hospital; Private Practice, Orthopaedics SA, Flinders Private Hospital

Jegan Krishnan, MBBS, FRACS, PhD, is a member of the following medical societies: Australian Medical Association, Australian Orthopaedic Association, and Royal Australasian College of Surgeons

Disclosure: Nothing to disclose.

Francisco Talavera, PharmD, PhD Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference

Disclosure: Medscape Salary Employment

Jerome D Wiedel, MD Chair, Professor, Department of Orthopedics, University of Colorado Health Sciences Center

Disclosure: Nothing to disclose.

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Pulmonary embolism within the pulmonary artery.
Ventilation-perfusion scan. Left image: Posterior view of normal findings on ventilation scan. Right image: Posterior view of a perfusion scan that reveals a perfusion defect in the left upper quadrant. The defect in the middle of the image is due to the position of the heart.
Helical CT scan of the pulmonary arteries. A filling defect in the right pulmonary artery is present, consistent with a pulmonary embolism.
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