Diagnostic assessment protocol for PE Diagnosis of PE will be assessed as described; briefly, all patients will undergo Ventilation-perfusion (V/Q) lung scanning or lung CT within 72 hours from the patient referral. In case of not diagnostic imaging, patients undergo ultrasonography of the lower limbs. Patients weill be diagnosed as having PE if they have a high-probability V/Q scan or an abnormal imaging result showing venous thrombi. All diagnostic tests will be performed by operators unaware of D-d assay results or PCP assessment. In cases of a positive diagnostic imaging test results, patients will be managed accordingly and they will receive full dose of anticoagulants.