Duplex ultrasound is a form of ultrasound that incorporates two elements:
1) B-mode, pulsed-doppler display to visualize the blood flow within a vessel;
2) Color-doppler display to visualize the structure and hemodynamics within a vessel. Both displays are presented on the same screen ("duplex") to facilitate interpretation.
Vascular ultrasound is the main branch of radiology that uses duplex. Vascular ultrasound, a subspeciality within ultrasound, helps determine multiple factors within the circulatory system. It can evaluate central (abdominal) and peripheral arteries and veins, it helps determine the amount of vascular stenosis (narrowing) or occlusion (complete blockage) within an artery, it assists in ruling out aneurysmal disease as well as being the main aid to rule out thrombotic events. Duplex is an inexpensive, non-invasive way to determine pathology. Duplex evaluation is usually done prior to any invasive testing or surgical procedure.