This is a protocol for a Cochrane Review (Diagnostic test accuracy). The objectives are as follows:

To investigate the ability of the D‐dimer test to rule out a diagnosis of acute PE in patients managed in the hospital outpatient setting who have had a pre‐test probability (PTP) for PE determined using a clinical prediction rule (CPR) but are not already established on anticoagulation at the time of recruitment to the study by estimating sensitivity and specificity.