The goal of this study was to prospectively compare the accuracy of transthoracic and transesophageal B-mode and Doppler echocardiography with helical CT for detecting acute pulmonary embolism.

Thirty-five consecutive patients underwent transthoracic and transesophageal echocardiography and contrast-enhanced helical CT. Echocardiographic examinations were analyzed for indirect criteria, including increased main pulmonary artery diameter, tricuspid regurgitation, and dilatation of the right ventricular cavity, as well as for direct thrombus visualization. Sensitivity, specificity, and negative and positive predictive values were calculated.

Pulmonary embolism was revealed by helical CT in 22 of 35 patients; in 11 of these 22 cases, central pulmonary embolism was seen. Transthoracic and transesophageal B-mode echocardiography failed to reveal pulmonary embolism in nine patients, two of whom had central pulmonary embolism. The sensitivity and specificity of the combination of both echocardiographic investigations were 59% and 77% respectively (82% and 92% for central pulmonary embolism). In three patients, pulmonary embolism was diagnosed by direct clot detection with transesophageal echocardiography. In two patients, only the indirect parameters indicated pulmonary embolism. Overall indirect echocardiographic parameters were characterized by a low sensitivity that ranged from 50% for tricuspid regurgitation to 21% for main pulmonary artery diameter.

In comparison with helical CT, transthoracic and transesophageal echocardiography had limited accuracy for detecting pulmonary embolism.