Emergency department nurse-based outpatient diagnosis of DVT using an evidence-based protocol

Objectives: To investigate the clinical validity of a nurse practitioner emergency department-based service for investigating outpatients with suspected deep vein thrombosis. Methods: A prospective management study was undertaken to investigate the safety of withholding anticoagulant treatment in patients who were negative for testing after application of an evidence-based protocol. The protocol involved a nurse assessment using the Wells pretest score followed by investigations tailored to the risk category ( variable combinations of strain gauge plethysmography, D-dimer and ultrasound). The main outcome assessed was the venothromboembolic complication rate in patients deemed to have deep vein thrombosis excluded by the protocol. Results: A total of 625 consecutive patients were evaluated between March 2003 and January 2007. Of these, 435 were eligible and 190 were ineligible. Four patients in the negative cohort were confirmed to have venous thromboembolism on follow-up. The incidence of venous thromboembolism in the 6-month follow-up period was therefore 1.04% ( 95% CI 0.41% to 2.65%). Conclusion: The evidence-based protocol used in this study can reliably exclude deep vein thrombosis in an outpatient population when applied as part of a nursebased evaluation.