Unlike the anatomy of your arteries, which is consistent in just about everyone, the anatomy of your superficial veins (the veins that are just under your skin) may vary considerably from person to person. The deep veins are usually relatively constant. It is usually easy to diagnose superficial veins, varicose veins and spider veins visually. The only way to achieve an accurate exam of the larger veins and deeper veins is with a duplex ultrasound in order to get a clearer picture of the underlying problem.
Ultrasound imaging, also called ultrasound scanning or sonography or venous duplex, is a non-invasive test that involves exposing part of the body to high-frequency soundwaves to produce pictures of the inside of the body. Ultrasound examinations do not use ionizing radiation (as used in x-ray). Because ultrasound images are captured in real-time, they can show the structure and movement of the body’s internal organs as well as blood flowing through blood vessels. Venous ultrasound (venoud duplex Doppler) provides pictures of the veins throughout the body and Doppler analysis of the blood flow within them.
A Doppler ultrasound study is always a part of a venous ultrasound examination. Doppler ultrasound is a special ultrasound technique that evaluates blood flow through a blood vessel in the abdomen, arms, legs and neck. Doppler ultrasound can be directed to a pinpoint area in the vein for special analysis of the venous blood flow.
Why is this procedure used?
The most common reason for a venous ultrasound exam in the hospital but less often in the office of a vascular specialist, is to search for blood clots in the veins of the legs or arms. This condition is often referred to as deep vein thrombosis or DVT. These clots in the legs may break off and pass into the lungs where they can cause a dangerous condition called pulmonary embolism. Blood clots from the legs to the lungs make up about 90+ percent of the blood clots that go to the lung. Only about 10 percent arise from the arms and are usually not as large as those originating from the legs and are usually not as life threatening.
The most common reason for venous ultrasound in our office is to document chronic venous insufficiency or reversed flow or obstruction in the veins of the legs.
Other reasons a venous ultrasound study is performed are, but not limited to:
- Determine the cause of long-standing leg swelling. In people with a common condition called varicose veins, the valves that keep blood flowing back to the heart in the right direction may be damaged, and venous ultrasound can help the vascular specialist decide how best to deal with this condition. The deep veins may also be blocked because of an old episode of thrombophlebitis (blood clots) which have scarred the veins shut thus keeping blood from returning normally to the heart from the leg.
- Aid in the placement of a catheter (tube) into a vein. Ultrasound can help locate the exact site of the vein and avoid complications, such as bleeding.
- Aid in the pinpoint placement of a needle into a refluxing vein to inject sclerotherapy when the vein cannot be visualized any other way.
- Map out the veins in the leg or arm so that sections of vein may be removed and used to bypass a narrowed or blocked blood vessel. An example is using sections of vein from the leg to surgically bypass narrowed coronary (heart)) arteries.
- Examine a blood vessel to a graft providing flow to a dialysis graft as well as the blood vessels emptying the graft if the graft is not working as expected. For example, the artery to the graft, the graft, or the vein draining the graft may have become narrowed or blocked.
Doppler ultrasound images can also help the physician to see and evaluate:
- Blockages to blood flow (such as clots).
- Narrowing of vessels and in this case the veins (which may be caused by multiple problems but the most common is a blood clot or residual scarring from an old blood clot).
- Tumors and congenital vascular malformation.
Lower extremities exam
Duplex imaging of the lower extremity veins is performed to assess the deep and superficial venous system of the lower extremities from groin to ankle level to determine the presence or absence of deep or superficial vein thrombosis. It also allows one to tell the direction of blood flow normally to the heart and abnormally back toward the foot. It is also used to identify perforating veins 360 degrees around the leg that may have become too large allowing the blood to flow back under the skin.
Common indications for the performance of lower extremity venous duplex imaging include, but are not limited to:
- Document new blood clots in the leg
- Document the source for pulmonary embolism (PE)
- Palpate leg cord (hard, thickened palpable vein)
- Determine the reason for dark pigmentation around your ankles
- Examine an ulcer on your ankle
- Document reversal of some blood flow that should go to the heart that now goes back to the foot
- Examine large veins visualized on your legs
- Examine extensive small veins around the ankles
- Document the development of abnormal veins after a previous blood clot in the leg
- Monitor post-venous interventional procedure (stenting, graft, endovenous laser ablation, radiofrequency ablation, sclerotherapy)
For deep vein thrombosis (DVT)
Duplex Doppler ultrasound for deep vein thrombosis (DVT) shows if there is a blockage in a leg vein. Such blockages are usually caused by blood clots, which can be dangerous and even life-threatening if they break loose and travel through the venous system to the lungs. If you have pain or swelling in one leg, your doctor may order an ultrasound to determine whether your symptoms are caused by a blockage.
For venous reflux
Duplex Doppler ultrasound for reflux is used to evaluate the valves inside the veins of the legs. If a patient requires a venous reflux exam because of vascular problems, this is nearly always done with the patient standing. The test is designed to identify problems inside leg veins (the one-way valves no longer work) that can cause problems with the direction of blood flow and the velocity of the blood flow in the leg. Identifying the cause of these problems is important to prevent damage caused by poor circulation and to plan appropriate treatment.
Upper extremities exam
Duplex imaging of the upper extremity veins is performed to assess the deep and superficial venous system of the upper extremities to determine the presence or absence of structural and functional changes that result from disease processes and to plan clinical management.
Some of the common indications for performance of upper extremity venous duplex imaging include, but are not limited to:
- Palpable arm cord (hard, thickened palpable vein)
- Document a sudden occlusion (blood clot) of the vein that drains your arm so that it can be treated before it becomes a permanent problem
How is the examination performed?
For a leg exam you will be asked to lie on your back with your head elevated slightly at approximately 30 to 45 degrees. For an exam of the upper extremities you will lie flat. A hand-held instrument, called a transducer, is used in the test. It looks like a microphone and sends and receives silent, high-frequency soundwaves. A gel will be spread on your arms or legs on the area to be examined. Applying a gel to the skin during an ultrasound procedure allows the transducer to pass over the skin more easily so that it makes better contact with the body. Also, during an ultrasound exam the transducer emits high-frequency soundwaves to obtain images of the inside of the body and the gel allows the soundwaves to pass through with little interference.
The person doing the test, the sonographer, will move the transducer down the length of the legs or arms while listening, looking, and putting slight pressure on the vein. The limb may need to be lightly squeezed at various times to check for the flow of blood in the vein. The transducer sends soundwaves that pass through the skin into the body. The soundwaves are reflected back to the transducer by the internal organs. These soundwaves contain information that is changed into a picture of the area being examined and the picture of the image is recorded and interpreted by your vascular specialist.
To test the blood flow, a second method is used. You will stand on a platform and the ultrasound probe will be over your upper leg, your calf muscle will be compressed and then the compression released. Flow should stay above the functioning valve and not fall back down your leg. The veins are examined with you standing to test for chronic venous insufficiency (fuctioning valves are lost or do not work properly). The deep veins of the legs that carry the majority of blood flow of your leg are also examined. Reflux greater than 1.0 seconds (1000 msec) is considered abnormal. For the great saphenous vein and small saphenous vein that are superficial under the skin, reflux of 0.5 seconds (500 msec) is considered abnormal. Perforating veins that go from superficial to deep in your leg may become enlarged and reflux of greater than 0.35 seconds (350 msec) is considered abnormal.
After all the above is done, if the reason for your varicose veins has not been identified, we may look for the origin 360 degrees around your leg using compression and release of compression maneuvers while watching the varicose veins. These can come from perforating veins as high as your buttocks muscles and go all the way to the ankle. This vein must be treated before or at the same time as the veins going all the way down your leg are treated.
There is another specific problem that occurs in women. There can be loss of the one-way valves in the ovarian veins down to the ovaries. This blood will then go around the rectum and vagina and be manifest as hemorrhoidal veins or large vulvar veins. These can then go all the way to your ankles. This may require special tests for diagnosis and these will be discussed with you. This problem can be treated and treatment is recommended before beginning treatment of the veins of your lower legs.
There is another congenital or acquired condition that causes problems that occur in the left leg. The right iliac artery that goes to your right leg at about the level of the umbilicus crosses the left iliac vein that drains your left leg. Many times this can be identified when examining your leg veins and will require special studies.
You may feel some mild discomfort as pressure is applied to your arm or leg, but in general the test is painless.
How should I prepare?
You should wear comfortable, loose-fitting clothing for your ultrasound exam. You may need to remove all clothing and jewelry in the area to be examined and will be given a gown to wear or disposable paper clothing that can be split up the sides.
A period of fasting is necessary only if you are to have an examination of veins in your abdomen. In this case, you will probably be asked to fast before your exam except for water and clear liquids 6 to 24 hours ahead of your appointment time. You will be asked to be n.p.o. (nothing by mouth) after midnight prior to the morning of your exam except for taking your medications. Your appointment will be scheduled for early morning. Otherwise, there is no other special preparation for a venous ultrasound of your legs or arms.
When will I know the results?
Once your exam is complete, you and Dr. Brazil will discuss the findings of your exam and treatment recommendations. Your options will be discussed in detail and you will be given plenty of opportunity to ask any questions or voice any concerns. A signed report will be sent to the physician who referred you and/or to your primary care physician.
Follow-up examinations are often necessary and the exact reasons for this will be explained to you. Sometimes a follow-up exam is done because:
- A suspicious or questionable finding needs clarification with additional tests or a special imaging technique.
- A follow-up examination may be necessary to monitor any chronic condition, such as an old blood clot from months or years ago, that has formed scar tissue in the vein.
- A follow-up examination will be necessary if you have an acute or recent blood clot to monitor that your treatment (anticoagulation) is effective. You may be seen in a few days to weeks and then again in a few months before stopping your blood thinner (anticoagulation).
- A follow-up examination may be necessary to monitor any change in a known abnormality.
- Follow-up examinations are many times the best way to monitor treatment to see if it is working or if an abnormality is stable or if an abnormality has progressed to where further treatment is needed.
What are the benefits and risks?
- Most ultrasound scanning is noninvasive (no needles or injections) and is usually painless.
- Ultrasound is widely available, easy to use and less expensive than other imaging methods.
- Ultrasound imaging does not use any ionizing radiation as in x-rays.
- Ultrasound scanning gives a clearer picture of soft tissues that do not show up well on x-ray images.
- Venous ultrasound helps to detect blood clots in the veins of the legs before they become dislodged and pass to the lungs. It may be able to tell the age of the clot and this is particularly true when it becomes chronic or scarred.
- It can also show the movement of blood within blood vessels.
- Collateral vessels (new vessels) will develop around chronic blockage and it is also important to know what veins remain to drain the leg back to the heart. This will help in protecting your leg from ulceration in later years.
- Compared to venography, which requires injecting contrast material into a vein, venous ultrasound is accurate for detecting blood clots in the veins of the thigh to the knee. A limitation to benefits is that in the calf, because the veins are small, ultrasound is less accurate unless an obvoius clot is seen. It is also less accurate above the inguinal ligament or groin in determining how far up into the abdomen they go. However, potentially most dangerous clots are lodged in the larger veins of your leg and in the large veins in your pelvis.
- It is helpful in diagnosing certain congenital abnormalities that involve the veins, such as Klippel-Trenaunay Syndrome, mixed venous arterial abnormalities, such as Parkes-Weber Syndrome, or other similar abnormalities.
- It is helpful in diagnosing other abnormal artery-to-vein communications following trauma, most notably stab wounds and gunshot wounds.
- For standard diagnostic ultrasound there are no known harmful effects.
We hope the information on these pages is both informative and helpful, but it is intended for education only. Please do note that no web site, no matter how much information is shared, can replace a consultation with your doctor and a vascular specialist. Medical technology and treatment are continually improving and evolving so before making any decision on treatment, it is always advisable to see your doctor first for a comprehensive evaluation of your vascular disease and other medical conditions.
At the Vascular Center of Wichita Falls, we work closely with your other physicians. If you have concerns about your arteries or veins, contact us. A referral is not necessary to make an appointment.