The purpose of this research is to measure changes in venous blood flow with an air-filled bladder under an intermittent pneumatic compression device cuff (used to prevent deep venous thrombosis) or venous diagnostic device cuff (used to detect deep venous thrombosis). The devices being used in the study are investigational and not FDA-cleared.

Inclusion Criteria:

• Venous ultrasound study to evaluate for lower extremity DVT unilateral and/or bilateral within previous 72 hours.

Exclusion Criteria:

• Patients with inaccessible target limb (ultrasound limb) due to bandages (wound, burn, lesion, etc) or cast.
• Patients with leg trauma, fracture, above or below knee amputation, or other condition in which compressing on the calf is medically inappropriate or not possible.
• Patients unable to provide informed written consent.

Subjects with venous ultrasound evaluation performed to rule out deep vein thrombosis