Information for Patients

VENOUS ULTRASOUND

A venous ultrasound provides images of the veins throughout the body. The most common reason for a venous ultrasound is to search for blood clots, especially in the veins of the leg. This condition is often referred to as Deep Vein Thrombosis or DVT.

These blood clots can break off and pass into the lungs, where they can cause a dangerous condition called pulmonary embolism. However, if the blood clot in the leg is found early enough, treatment can be started to prevent it from passing to the lung.

A venous ultrasound study is also performed to:

• Determine the cause of leg swelling. In people with varicose veins, the valves that keep blood flowing back to the heart in the right direction may be damaged, and a venous ultrasound can help the specialist decide how best to deal with this condition.
• Aid in the placement of a needle or catheter into a vein. A venous ultrasound can help locate the exact site of the vein and avoid complications such as bleeding.
• Map out the veins in the leg or arm so that pieces of vein may be removed and used to bypass a narrowed or blocked blood vessel. An example is using pieces of vein from the leg to surgically bypass narrowed heart (coronary) arteries.
• Examine a blood vessel graft used for dialysis if it is not working as expected e.g. the graft may be narrowed or blocked.

A Doppler ultrasound study may be part of a venous ultrasound examination. Doppler ultrasound is a special ultrasound technique that evaluates blood flow through a blood vessel, including the body's major arteries and veins in the abdomen, arms, legs and neck.

Doppler ultrasound images can help the physician to see and evaluate:

• Blockages to blood flow (such as clots) 
• Narrowing of vessels (which may be caused by plaque)
• Tumors and congenital malformation