NEW YORK (Reuters Health) - A diagnostic strategy that combines clinical assessment, D-dimer testing, venous ultrasound, and helical CT appears to be a safe and effective method of detecting pulmonary embolism in outpatients, European researchers report.

The findings, which appear in the March 1st issue of The American Journal of Medicine, are based on a study of 1290 patients who presented to the ER and were screened for pulmonary embolism. Of these patients, 965 met clinical criteria for suspected pulmonary embolism and were evaluated with the diagnostic strategy. The patients were followed for 3 months.

After clinical assessment, the next step in the strategy is D-dimer testing, lead author Dr. Arnaud Perrier, from Geneva University Hospital, and colleagues note. A value below 500 micrograms per liter suggests no pulmonary embolism and indicates no further testing is necessary, while a higher value indicates the need for venous ultrasound.

If ultrasound shows a DVT then appropriate treatment is instituted. If not, then helical CT scanning is performed. If helical CT shows a pulmonary embolism, then treatment is given, if pulmonary embolism is not present then the clinical probability of pulmonary embolism is reconsidered.

With a low or intermediate probability pulmonary embolism is considered unlikely and no treatment is given, whereas high probability cases are referred for angiography to formally rule out pulmonary embolism.

D-dimer testing ruled out DVT in 280 patients (29%) and ultrasound diagnosed DVT in 92 patients (9.5%), the researchers note. Helical CT diagnosed pulmonary embolism in 124 (12.8%) of the 593 patients who required this test. Of the remaining 469 patients, 458 had no pulmonary embolism on CT and 11 had inconclusive findings (V/Q scanning or angiography diagnosed pulmonary embolism in 7 and no pulmonary embolism in 4).

Of the 458 patients with no pulmonary embolism on CT, 450 (46.6%) were judged to have a low or intermediate probability of pulmonary embolism. The remaining 8 patients, thought to have a high risk of pulmonary embolism, underwent angiography and 2 were ruled in for pulmonary embolism.

Overall, pulmonary embolism was identified in 23% of patients, the authors state. The 3-month thromboembolic risk for patients classified as having "no pulmonary embolism " was 1.0%.

The current diagnostic strategy "yielded a diagnosis in 99% of outpatients suspected of pulmonary embolism, and appeared to be safe, provided that CT was combined with ultrasonography to rule out the disease," the researchers state.

Am J Med 2004;116:291-299.

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