Bedside ultrasound is a valuable tool to detect Deep Vein Thrombosis, DVT, in lower extremities. As 1 in every 1000 people has a thrombosis in their lower leg, it is important to detect the thrombosis so that it can be treated to minimize the onset of a Pulmonary Embolism, PE. A PE is when the clot from the thrombosis travels to the lung. More than 600,000 PEs occur in the United States each year, resulting in 50,000 to 200,000 deaths a year.
So how do we detect a thrombosis using ultrasound??
First, there are three primary places that a thrombosis can occur: the common femoral vein at the saphenous junction; the proximal femoral veins; and the popliteal vein.
While these are the places that a thrombosis is typically detected, a thrombosis can occur anywhere in the veins of the leg. If a patient has swelling or pain in the lower legs, the veins should be checked for a thrombosis.
Secondly, what is a thrombosis: A thrombosis is a reduction or blockage in the vein due to clotting of the blood. A thrombosis occurs due to a pooling of blood in a vein near a backward flow valve or vein junction. Anywhere the normal flow can be interrupted, the blood can pool and create an opportunity for a clot.
And finally, how do we detect a thrombosis using ultrasound. We simply scan the veins, compressing the vein with the ultrasound probe at the typical places a thrombosis might occur. If the vein completely compresses than there is not a thrombosis. If the vein does not completely compress then you are viewing a thrombosis.
There are many references online – simply search “detecting DVT with ultrasound” and you will find detailed descriptions with proper techniques and pictures on probe positioning and resultant ultrasound images. One of my favorites is Joel Turner’s DVT chapter in “Point of Care Ultrasound for Emergency Physicians” ISBN 978-0-9880123-0-1