LETTER
Ultrasonography of Leg Veins in Patients Suspected of Having Pulmonary Embolism
Arnaud Perrier, MD, and
Henri Bounameaux, MD
1 February 1998 | Volume 128 Issue 3 | Page 243
TO THE EDITOR:
In their study on the diagnostic utility of lower-limb venous compression ultrasonography in patients suspected of having pulmonary embolism [1], Turkstra and colleagues found that ultrasonography had a sensitivity of 29% (95% CI, 22% to 37%) and a specificity of 97% (CI, 94% to 99%). On the basis of these results (a low sensitivity and a suboptimal positive predictive value), they conclude that "compression ultrasonography should be used with great caution in patients suspected of having pulmonary embolism."
We disagree with that conclusion on several grounds. First, the low sensitivity may be explained by the inclusion of both inpatients and outpatients. In our recent outcome study of 671 consecutive outpatients presenting to an emergency department with suspected pulmonary embolism [2] (in which we used an ultrasonography protocol similar to that used by Turkstra and colleagues), we found a higher sensitivity-51% (CI, 44% to 58%). On the other hand, in an ongoing study of inpatients, sensitivity of ultrasonography seems lower (approximately 30%) in patients hospitalized in medical and surgical wards; this probably reflects a higher proportion of deep venous thrombosis of the calf in this population.
Second, the specificity of ultrasonography (97%) is identical to that of lung scanning [3], which is universally accepted (including by Turkstra and colleagues) as a diagnostic standard for pulmonary embolism. Thus, the proportion of patients inappropriately treated on the basis of ultrasonography results or of a high-probability lung scan are not different. Finally, in a recent economic analysis [4] that was based on the results of a large management trial [5], we showed that combining ultrasonography alone with lung scanning and angiography was marginally cost-effective and that the association of plasma D-dimer measurement and ultrasonography yielded substantial savings.
In conclusion, we believe that ultrasonography is a useful instrument in outpatients suspected of having pulmonary embolism because it yields a highly probable diagnosis of thromboembolic disease in up to 15% of patients in whom this disorder is suspected.
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Author and Article Information
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Geneva University Hospital; CH-1211 Geneva 14, Switzerland
1. Turkstra F, Kuijer PM, van Beek EJ, Brandjes DP, ten Cate JW, Buller HR. Diagnostic utility of ultrasonography of leg veins in patients suspected of having pulmonary embolism. Ann Intern Med. 1997; 126:775-81.
2. Perrier A, Desmarais S, Goehring C, de Moerloose P, Morabia A, Unger PF, et al.D-dimer testing for suspected pulmonary embolism. Am J Resp Crit Care Med. 1997; 156:492-6.
3. Value of the ventilation/perfusion scan in acute pulmonary embolism. Results of the prospective investigation of pulmonary embolism diagnosis (PIOPED). The PIOPED Investigators. JAMA. 1990; 263:2753-9.
4. Perrier A, Buswell L, Bounameaux H, Didier D, Morabia A, de Moerloose P, et al. Cost-effectiveness of noninvasive diagnostic aids in suspected pulmonary embolism. Arch Intern Med. 1997; 157:2309-16.
5. Perrier A, Bounameaux H, Morabia A, et al. Diagnosis of pulmonary embolism by a decision analysis-based strategy including clinical probability, D-dimer levels, and ultrasonography: a management study. Arch Intern Med. 1996; 156:531-6.
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