NICE encourages further research comparing ultrasound-enhanced, catheter-directed thrombolysis for deep vein thrombosis against catheter-directed thrombolysis alone. Patient selection should be documented, including the duration and extent of thrombosis. The dose of thrombolytic agent used and the duration of thrombolysis should be reported, together with all complications. Outcome measures should include the success of thrombolysis (complete, partial or failed) and long-term sequelae. NICE may update the guidance on publication of further evidence.