According to post-mortem results, it has been seen that the diagnosis of pulmonary embolism, even in cases of important extension, is often not performed, so researchers have wondered whether pulmonary embolism screening should be performed in patients with deep venous thrombosis (DVT), even in the absence of respiratory symptoms. A systematic review has been performed on 28 prospective trials to verify the prevalence of pulmonary embolism in patients with DVP. Researches have been stratified into two groups: in the first one, all the cases where pulmonary embolism has been diagnosed with a “high probability” through an investigation on ventilation/perfusion relation (according PIOPED criteria) or through pulmonary angiography has been included; in the second one, all the cases where diagnosis has been performed through the determination of ventilation/perfusion relation not using PIOPED criteria. In the overall, silent pulmonary embolism has been diagnosed in 32% of 5233 patients affected by DVP (27% in the first group, 37% in the second one). Prevalence has been higher in subjects affected by proximal DVP(36% vs. 13% in distal DVP). The presence of silent pulmonary embolism has been also associated with a greater risk of recurrent pulmonary embolism.
