Clinical Validity of Negative Helical Computed Tomography for Clinical Suspicion of Pulmonary Embolism

Abstract

Background: Helical computed tomography has been introduced for the diagnosis of pulmonary embolism. Objective: To determine the clinical safety of withholding anticoagulant treatment in patients with suspicion of pulmonary embolism and negative helical computed tomography study. Methods: During a 9-month period, we performed a prospective study including 209 consecutive patients who underwent helical computed tomography for clinical suspicion of pulmonary embolism. In 53 patients (25.5%), helical computed tomography was diagnostic for pulmonary embolism, and in 24 patients (11.5%) it was indeterminate. In 132 patients (63%), the examination was negative for pulmonary embolism and no anticoagulation treatment was given. A clinical 3-month follow-up was carried out. During this period, 29 patients (22%) were excluded because anticoagulation therapy was initiated for other reasons, or because other diagnostic techniques were performed for pulmonary embolism. Four patients were lost in the 3-month period. In the end, 99 patients (75%) were included in the clinical follow-up. Results: Out of the 99 patients, 9 (9%) died during the 9-month follow-up, the cause of death in each case was not due to thromboembolic venous disease. No venous thromboembolic events were detected in the other 90 patients. Negative predictive value of helical computed tomography for pulmonary embolism was 99.09% (95% CI, 95.03–99.97%). Conclusions: In patients with clinical suspicion of pulmonary embolism and initial negative helical computed tomography from whom anticoagulants are withheld, no thromboembolic disease was detected in a 3-month follow-up. We consider helical computed tomography an effective method for ruling out pulmonary embolism as well as a front-line tool for diagnosis.