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Plasma D-dimer: a useful tool for evaluating suspected pulmonary embolus
K A Harrison1, W D Haire, A A Pappas
1Department of Radiology, University of Nebraska Medical Center, St, Omaha 68198-1045.
Summary
A normal D-dimer blood test is a reliable negative predictor for pulmonary embolus, helping to rule out the condition. This aids in evaluating patients when lung scans are inconclusive for pulmonary embolism.
Area of Science:
- Medical Diagnostics
- Cardiovascular and Respiratory System
Background:
- Ventilation-perfusion lung scanning is a standard diagnostic tool for pulmonary embolism.
- There is a need for rapid screening tests to complement lung scans, especially in indeterminate or clinically discordant cases.
Purpose of the Study:
- To evaluate the utility of the D-dimer assay as a rapid screening test for pulmonary embolism.
Main Methods:
- Prospective study involving patients referred for lung scanning.
- Plasma D-dimer latex agglutination assay performed concurrently with lung scanning.
- Pulmonary angiography used as the gold standard for diagnosis.
Main Results:
- Of 64 patients undergoing pulmonary angiography, 16 had confirmed pulmonary emboli.
- Only one patient with pulmonary embolism had a normal D-dimer.
- A normal D-dimer was observed in 27 of 48 patients without pulmonary embolism.
Conclusions:
- A normal D-dimer level demonstrates a high negative predictive value (0.97) for pulmonary embolism.
- The D-dimer assay can serve as an effective negative predictor, aiding in the exclusion of pulmonary embolism.
- While elevated D-dimer is nonspecific, a normal result is valuable in diagnostic decision-making.