Is pulmonary angiography essential for the diagnosis of acute pulmonary embolism?

The records of 158 patients who underwent pulmonary angiography for the presumed diagnosis of acute pulmonary embolism were retrospectively reviewed. Of the 111 patients in the category of high probability for pulmonary embolism based on clinical impression, 60 patients (54 per cent) had a positive pulmonary angiogram. Of the forty-seven patients in the low probability group, ten (21 per cent) had a positive angiogram. Forty-eight of the seventy-three patients (66 per cent) with a high probability lung scan had a positive pulmonary angiogram. Eleven of twelve patients (92 per cent) with a high probability ventilation-perfusion scan had a positive pulmonary angiogram, and two of eight patients (25 per cent) with a low probability ventilation-perfusion scan had a positive pulmonary angiogram. The mean PO2 of patients with a positive pulmonary angiogram was 64 mm Hg, and the mean PCO2 30 mm Hg. The mean PO2 of patients with a negative pulmonary angiogram was 63 mm Hg and the mean PCO2 34 mm Hg. Based on these data, we believe that the accuracy of pulmonary angiography in diagnosing acute pulmonary embolism is much higher than that of the clinical impression, arterial blood gas determinations, and lung scanning technics.