Emergency Medicine Pulmonary Embolism Testing Multicentre Study

Inclusion Criteria: * Emergency department patient who is tested by an emergency physician for PE Exclusion Criteria: * Patient is \< 18 years of age * No documentation of whether PE is the most likely diagnosis * D-dimer is not tested or else not resulted during the emergency visit * The D-dimer level is known before documentation of whether PE is the most likely diagnosis * The D-dimer is ordered prior to the physician assessing the patient * The patient has previously registered that they opt out of all research at the participating site * The patient leaves against medical advice * The patient has had PE or deep vein thrombosis imaging (CT pulmonary angiogram, ventilation-perfusion scan or lower limb ultrasound) within prior 30 days * There is a new (non-PE) indication for anticoagulation * The patient was initiated on treatment for presumed PE prior to PE testing * The patient has previously been enrolled into the study * The patient has a prior history of lower extremity deep vein thrombosis without availability of a baseline ultrasound scan * The patient was transferred from another hospital organization * The patient does not reside in Ontario * The patient has no valid Ontario Health Insurance Plan card