Clinically suspected pulmonary embolism: is it safe to withhold anticoagulation after a negative spiral CT?

The goal of this study was 3-month clinical outcome in nonanticoagulated pa tients with clinically suspected acute pulmonary embolism (PE) following a negative spiral CT. During a 6-month period 305 patients underwent spiral C T, of whom only 8 also had a lung scintigraphy. In patients with a final CT report read as not positive for acute PE, all hospital records and answers to a patient questionnaire were analyzed for episodes of venous thrombembo lism (VTE). Acute PE was diagnosed at spiral CT in 61 patients (20 %). Twen ty-six of the remaining 244 patients were excluded from further analysis be cause of (a) longterm anticoagulation due to symptomatic acute deep venous thrombosis (n = 5), clinically diagnosed acute PE (n = 2), chronic recurren t VTE (n = 4), and cardiac disorders (n = 5); and (b) a normal perfusion sc intigram (n = 4) or a negative pulmonary arteriogram (n = 6). Three patient s were lost to follow-up. Among the remaining 215 patients only 10 had unde rgone a negative lower extremity venous study. Sixteen patients (7 %) died during the follow-up period, 6 of whom underwent autopsy. Venous thrombembo lism was diagnosed in three of the 215 patients (1.4%, 95 % confidence limi ts: 0.5-4.0 %), one causing the patient's death. Two patients had advanced thoracic malignancies and the third severe chronic obstructive pulmonary di sease (84 years old). A negative spiral CT may be able to exclude clinicall y significant acute PE with the same accuracy as a normal lung scintigraphy or a negative pulmonary arteriography.