In our office we use photoplethysmography to help assess reflux in your leg veins.  A small light emitting (and receiving) probe is applied to the skin of your leg.  We then ask you to pump your foot up and down about five times.  This activates the venous pump of your leg.  The blood should exit your leg.  The light that is transmitted through your skin reflects off the red blood cells in the tissue.  As the number of red cells decreases the amount of light that is reflected back decreases.  After you stop pumping your foot, blood again enters your leg.  It normally takes about 20 or so seconds for the blood to refill coming down your arteries.  If the blood refills too quickly, we know it is coming the wrong way, backwards, refluxing down your veins.  This information is automatically displayed and recorded on paper. Click to see the photoplethysmograph machine and probe.