Hi, my name is George Berdejo and I am Director of Vascular Ultrasound Services at the Moses and Weiler Divisions of the Montefiore Medical Center in New York City. I am also a member of the Society for Vascular Ultrasounds Product Committee along with Billy Zhang and chaired by Terry Case. This program is being supported by an unrestricted educational grant that is provided by the Radiology and Vascular Ultrasound Divisions at GE Healthcare and in cooperation with TIPTV. Today I will be discussing the Society for Vascular Ultrasounds Lower Extremity Venous Duplex Professional Performance Guidelines. Now let's get right into the guidelines. Guideline number one is the patient communication guideline and it's imperative that you establish a dialogue with your patient before the start of the examination. This sort of helps to ease the tension and also eliminates the anxiety that's associated with almost any imaging procedure. In our facility we use an acronym and that's called AIDET, A-I-D-E-T, and the letters stand for acknowledge, introduce, duration, education and explanation, and also thank you. And let's just get right into the guideline and the first part of it, the first component is the introduction component. And you always want to go into the examination room and sort of acknowledge the patient and also introduce yourself. So you might go in and say good morning Mr. Smith, my name is George and I'm here today to perform your lower extremity venous duplex examination. You also want to explain the procedure to the patient, in other words tell them about its non-invasive nature, explain to them that the test is painless, you're there to rule out any thrombus within the veins that might put them at risk for complications such as pulmonary embolus. You also want to respond to questions and concerns that the patient might have. And this is important because the anxiety related to these types of procedures and just about any medical procedure really is related to the patient's lack of information about what might be happening. The other part is to educate and to also explain to the patient what's going on in terms of the risks associated with the disease process that you're trying to diagnose. Finally, the patient may have some questions in terms of diagnostic and also prognostic issues. And those questions really are best referred to either the referring physician or to your medical director when they're relevant. The next guideline is guideline two and that's the patient assessment and physical examination portion of the guideline. And this really is an essential component of the whole process and it really starts with an assessment of any contraindications or limitations to the performance of the lower extremity venous duplex evaluations. One other important thing is also to assess the ability of the patient to tolerate the procedure and that is quite critical. It's important to explain to the patient the components of the examination. One of the biggest components in terms of the diagnosis of deep vein thrombosis is the ability to compress the vein. The inability to perform that procedure really does limit the examination and you're going to have to look for other parameters in order to assess for the presence of deep vein thrombosis. So it's important to explain that to the patient. You want to be able to obtain a very complete and pertinent history relevant to the examination being performed. Another very important component of the assessment piece is to obtain a complete focused physical examination. Now this might include an assessment for the presence of swelling of one or the other extremities or perhaps both, looking for the presence of varicosities in either lower extremity and also might include a measurement of the calf circumference which is quite critical in patients suspected of having deep vein thrombosis. Once all that information has been acquired, you then want to verify that the requested procedure is relevant to the patient's presenting symptoms. In the absence of that, you might need to make a phone call in order to correlate with the referring physician and then perform the procedure that in fact really is indicated in the presence of those symptoms. When directed, you may need to perform adjunctive procedures. One example of that might include a negative examination in the presence of unilateral leg swelling might prompt you also to look at the iliac veins and you might need to make an extra phone call in terms of findings such as that one. The third part of the guidelines really refer now to the examination piece and let's start out with equipment specifications because you need to use the right equipment in order to obtain all the appropriate data. Your equipment specifications in terms of lower extremity venous duplex imaging really should include equipment that's able to offer you the ability to obtain Doppler spectral waveforms and this may be with or without color Doppler imaging. In my experience, it's not absolutely necessary to have color Doppler, however, I will say that it does help both in terms of decreasing the examination time primarily because it allows you to more readily identify the vessels of interest by color. So although you don't absolutely need to have it, it does help. You want to use an imaging carrier frequency in the range of 5 megahertz. Of course, the type of frequency that you use will be dependent on the leg that you're looking at and also on the patient population. In thinner patients or in thinner pediatric patients, you might be able to opt for a higher frequency transducer, but by and large, the 5 megahertz transducer would be most appropriate for most of the patients that you're looking at. Doppler carrying frequency should be in the range of 3 megahertz. And it's also important to be able to document the findings of your examination and you want to do that either with videotape, with film or digital storage or perhaps hard copy images. In my opinion, probably best to do this with some type of real-time imaging capability. So if you have CineLoop capability or videotape, that's probably best because you want to be able to go back if you have to and review these studies in real-time since they are real-time imaging procedures. The examination itself should start out with the patient in the supine position. You want to put the examination table in a reverse Trendelenburg orientation so that the heart is higher than the lower extremities. You want to start out your examination by identifying the common femoral vein at the level of the inguinal ligament, somewhere near the sapheno-femoral junction. And then you want to examine all of the major veins from the level of the groin down to the ankle. You should be performing transverse transducer compressions about 1 to 2 centimeters apart along the length of the entire venous system. When and where you suspect the presence of pathology within the venous system, you should assess for the presence of echoes and also for the appearance of the thrombus in terms of its echogenicity, also in terms of the location and the extent of thrombus when and where you think it's present. You should confirm if you do suspect that there is deep vein thrombosis. That finding really should be confirmed with the presence of a spectral waveform analysis. If you think there's complete occlusion, you really shouldn't be seeing or hearing any flow there, and you might want to supplement that by using some color flow imaging as well. When you're performing unilateral evaluations, and this is key to the examination, and one of the ICAVL guidelines calls for the examination of the contralateral common femoral waveform. This is important because you want to do a side-to-side comparison and assess for asymmetry, and then perform the appropriate adjunctive procedures based on the findings of your Doppler spectral waveform analysis. That takes us now to guideline four, which is a review of the diagnostic exam findings. Once your study is completed, you really want to go back and then review all of the data that has been acquired. Now, ideally, you should be performing all of your examinations per some written protocol, and this is important because the presence of a protocol, a very detailed step-by-step protocol really does limit the potential for error in the performance of your examination. When you sit down and review the data that you've acquired, you really want to do that before the patient leaves. It's not uncommon that upon review of your exam findings with your technical director or your medical director, you may have to go back and re-scan a patient or perhaps acquire an image that wasn't acquired when you were doing the examination, and you don't want to have to have to call the patient back in. So best to do your review of your data before your patient leaves. One important thing also is to review any previous examinations that may have been performed either in your laboratory or somewhere else, and the reason you want to do that is because it's nice to provide a comparison from one study to the next in terms of either progression or regression of thrombus in patients who have had previous episodes of deep vein thrombosis. You should record all your technical findings on what we call a preliminary worksheet, and this is important because it's that preliminary worksheet in addition to the images that the interpreting physician will use in order to perform their interpretation of your study. Quite critical to all of the data that's acquired and in terms of writing up your preliminary findings is to include some note of the completeness of your study. If anything has been left out, if the study was limited either by your inability to compress, and not unusual, most of these patients come in with pain, and sometimes your ability to compress the vessels is limited. Another reason your exam might be limited is in a patient who has overlying dressings or perhaps ulceration that doesn't allow you to put the transducer in some of these places. You really need to include that in your report because I would submit that in the absence of being able to image the vessel, you really can't absolutely exclude the presence of thrombus at that site. Finally, your report should include documentation in terms of the examination date, the clinical indications, as well as some notation of the technologist who's performed the evaluation as well as the examination, and that may be more than one person. Section 5 now takes us to the presentation of the examination findings, and again, it's important to present a record of your diagnostic images, your data, any explanations regarding limitations of your findings, and your technical worksheet to the interpreting physician. Occasionally, it may be necessary to provide a preliminary result, and when this is necessary, you probably should work within the guidelines of the scope of practice as well as the guidelines and limitations within your own policies and procedures. In some laboratories, it may be absolutely normal for a technologist to call a referring physician in order to provide a preliminary finding. In other laboratories, that job is done by the medical director or the interpreting physician of the day. Occasionally, especially in the sicker population, it may be necessary to alert the vascular laboratory medical director in terms of medical emergencies, and when that's appropriate, you need to find the appropriate health care provider and provide immediate medical attention when that's indicated. Guideline 6 now takes us to exam time recommendations. Fundamental elements of the lower extremity vein exam really are two, and the total allotment for the overall examination is about 75 minutes, and that's divided between indirect exam components such as writing the study up, acquiring your images, translating all your information to the worksheet, and also the direct exam components, which is really the imaging itself, and we usually allocate about 30 minutes in terms of the worksheet, the indirect component, and about 35 to 45 minutes for the actual imaging itself, for a grand total of 75 minutes. Guideline 7 now takes us to continuing professional education, and I think really it's incumbent upon and very important for the technologist or sonographer to keep him or herself abreast of the current state of affairs in terms of the diagnosis of lower extremity deep vein thrombosis, all of the advances in diagnosis and treatment, changes within lower extremity venous duplex evaluation protocols, advances in ultrasound technology, and also advances in other technology related to the diagnosis of deep vein thrombosis. This can be accomplished through activities such as this one, or also by attending meetings sponsored by the Society for Vascular Ultrasound. And finally, for more details regarding these and some of the other professional performance guidelines, I will refer you to the Society for Vascular Ultrasound's website at www.svunet.org. My name is Dr. Mark Oliver. I am co-director of the Noninvasive Vascular Lab at Morristown Memorial Hospital, and attending physician in internal medicine and vascular medicine at Morristown Memorial Hospital in Morristown, New Jersey. I will be discussing lower extremity venous duplex evaluation for DVT. Venous diseases can be divided into venous thromboembolism and venous insufficiency. Venous thromboembolism, acute, consists of venous thrombosis, superficial or deep, and or pulmonary embolism. This presentation will emphasize the testing for DVT. To start off with, we'll talk about the introduction and background of DVT, or deep vein thrombosis. There are 500,000 cases of DVT annually that have been approximated. Some people feel that this approximation is too low and that it's greater than 2 million cases a year. Greater than 50% of these cases are unrecognized. 200,000 cases of fatal PE occur each year. Most DVT is a cult resolving spontaneously. One person in 20 will develop a DVT. DVT is more common in women. DVT usually does affect individuals older than 40 years. The exact incidence of DVT is unknown. One third of the patients with symptomatic DVT will manifest with pulmonary embolism. Two thirds will manifest DVT alone. Thirty percent will die within 30 days. Twenty percent suffer sudden death due to PE. And 30% develop recurrent DVT within 10 years. The incidence of venous thrombosis is considerably higher in hospitalized patients. Ten to 30% of medically ill patients in the hospital will have a pulmonary embolism. It has been shown that 10 to 12% of patients who die in the hospital will have had pulmonary emboli involved with that. As a result, it's felt that pulmonary embolism is probably the most preventable cause of death in the hospital. The long-term complications related to morbidity of DVT relate to venous ulceration and venous insufficiency, which in the lower leg may affect 0.5% of the entire population. In respect to chronic venous insufficiency as a morbid outcome from DVT, the long-term outcome depends on location, extent of residual thrombus, degree of valvular incompetence, and also the speed at which the thrombus is eliminated. This can be associated with pain and or swelling, pigmentation, varicose veins, ulcerations, or no symptoms at all. In respect to pulmonary embolism, the most immediate concern when DVT is suspected is certainly pulmonary embolism. Normal DVT with major volume involved with the clot is more likely to be fatal. FEM and POP DVT may or may not cause death. This is dependent on other factors, such as pulmonary reserve and other comorbidities. Tibial vein thrombosis rarely causes a significant PE, but it must be remembered that it can still cause PE. It should be also remembered that in CAF DVT that this can propagate to the POPatil FEM level in about 20% of cases. It also should be remembered that in major DVT, which we consider FEM, POP, or above, if those patients are untreated, about 50% of those patients will have pulmonary emboli. It should be remembered that in minor DVT, which is below the POPatil, that about 1% to 5% of those patients will have PE, and again, to remember that 20% could potentially propagate. With respect to anatomy, we can categorize our blood vessels to arteries that move blood away from the heart to the periphery, capillaries that allow exchange of materials between blood and cells, and veins that return blood from the periphery to the heart. In respect to vessel walls, vessels are basically tubes, largest composed of three layers. This is microscopic anatomy. The layers are the same in the veins and the arteries. However, the size and strength and composition is different. In general, the vein vessel walls are thinner, therefore making the vein walls easy to collapse. The adventitia, as you can see here, has vasobasorum, and it is considerably thinner in the vein, as you can see, compared to the artery. The media in the artery is thicker than in the vein and also has elastic fibers, which are much greater in the artery than in the vein, and thus can accommodate the large pulsatile flow from the heart. The intima is a single-celled endothelium that exists in both. As you can see, the endothelial cells here, and the major difference in the arteries and veins in this respect is the presence of venous valves, where there are no valves in the artery. Also, it is important to note these endothelial cells have an antithrombotic component to them, such when there is injury to these cells, there can be a higher risk of clotting. Deep veins lie under both the skin and the fascia. They're surrounded by muscle and aid in blood flow. The major deep veins are named for arteries they accompany in the lower extremity. The venous anatomy consists of three different systems. The deep veins, the superficial veins, the perforating or communicating veins. There are three pairs of deep veins in the calf. There are at least two per artery, but there may be more than two per artery. If you notice here, we have one of them being the posterior tibial, which arises posterior to the tibia and goes along the leg here, and it forms a confluence with the, if you will, a common trunk with the peroneal vein here, which eventually becomes a confluence into the popatial vein. The peroneal vein here is existing medial to the tibia and runs along here, and also as mentioned before, will form a common trunk, which becomes a confluence into the popatial vein. And finally, we have the anterior tibial artery, which arises from the dorsal rete and continues in the anterior lateral segment here between the interosseous membranes, and as you can see, it forms a little bit further up in a common trunk, which becomes the popatial. So thus, these two confluences form the popatial vein that you can see here. In addition to that, there are, in the intramuscular areas, there are gastrocnemius and soleal veins that drain the musculature. There is a lot of variation to the venous anatomy. The gastrocnemius veins, in general, will drain into the popatial, whereas the soleal veins will drain, in general, into the posterior peroneal veins. Again, this is variable. It also should be noted that these veins have clots in these veins. This is one of the most common sites for early clot formation, for clots to form in the leg. As we continue on with our anatomy, we can see that the popatial vein, as you can see here, crosses the knee and becomes the femoral vein at the adductor canal region here. You can see that most of the popatial vein is actually above the knee. You can also see that the femoral vein here joins the profunda vein here to become the common femoral vein. You should also note here that the femoral vein and the common femoral vein are, these veins are, this is medial to the arteries here. To continue on, the common femoral vein, as you can see here, at the level of the inguinal ligament becomes the external iliac vein. The external iliac vein joins the internal iliac vein, as you can see here, to become the common iliac vein. At the area of the umbilicus, the common iliac veins join together to become the IVC. It should be noted in this diagram here that the right common iliac artery here crosses over the left common iliac vein, and that's sort of an accordion, if you will, a compression phenomenon can occur between the spine and the right common iliac artery over the common iliac vein. This is why it is thought that there may be more common left DVT than right DVT and may occur in certain syndromes, such as the Matherner syndrome. The IVC, as noted, is also to the right of and anterior to the aorta in this diagram. The superficial veins are located under the skin above the fascia. They can sometimes be seen under the skin and sometimes used as conduits for revascularization. The following are the superficial veins. The anatomy of the great and small saphenous veins. The great saphenous vein is noted here. It is the longest vein in the body. It starts, as you can see, anterior to the medial malleolus. It runs along the medial aspect of the leg and joins the femoral vein in the sapheno-femoral junction at the level of the fascia ovalis. We can see here the small saphenous vein system where the small saphenous vein begins posterior to the lateral malleolus. It runs along the seam or the posterior aspect of the calf and most of the time will drain into the popliteal vein, although there are variations to that anatomy. The sapheno-femoral junction is an important area because this is a potential area for clot formation. Many patients develop superficial phlebitis, which in and of itself may not be that life-threatening, but it is important to note that we have to follow some of these patients that have more proximal superficial phlebitis because some of these areas may extend into and form a tail into the common femoral vein, which can lead to a pulmonary embolism. So this becomes a very important area to incinate. In respect to the perforating veins, these veins connect the deep and superficial venous systems. They regulate the amount of blood in the superficial veins. They penetrate the fascia at various levels along the leg. Valves direct flow from superficial to deep venous system, and most are abundant below the knee. This is a nice demonstration of showing the relationship between the great saphenous vein and its major perforators. Note that there are perforators above in the thigh and just below the knee, but that most of the perforators, as you can see, are in the area of the lower leg, the distal leg here, and as a result of that, when there are abnormalities in these perforators, such as in chronic venous disease or chronic venous insufficiency, more of the pathology will be noted in this part of the leg. The most significant feature of the venous system are the bicuspid valves that you see in this diagram. They allow the flow of blood in the cephalad direction only. When there is reflux, if these are not working properly, one can develop venous hypertension. As a result, develop complications, pathology. ♪♪♪ In respect to the physiology of the venous system, in respect to physiology of venous flow, veins are collapsible tubes. The shape is determined by transmural pressure. As you can see here, in a system with low transmural pressure, the tissue pressure is greater than the interluminal pressure. As a result, with very little change in pressure, the veins are allowed to move With very little change in pressure, the veins are allowed to accommodate a larger volume of blood, and therefore they can act as a good storage system. Whereas in a situation with a higher transmural pressure, the tissue pressure being greater than the interluminal pressure, the vein walls are very stiff and cannot accommodate as much of the amount of blood with change in pressure. The pressure in a blood vessel is equal to the dynamic pressure, heart, and hydrostatic pressure, which is defined as the weight of a column of blood. You can see here, as a result, in the supine position, the dynamic pressure will be the major pressure component and the hydrostatic pressure will not be, being very negligible. However, the opposite occurs in the standing position, when now, in the venous side, the hydrostatic pressure becomes a major component in addition to dynamic pressure. In respect to physiology of flow and respiration, respiration is the driving force for phasic flow in the supine position. In inspiration, there's an increase in intra-abdominal pressure and a decrease in the intra-thoracic pressure. The end result is little or no flow from the lower extremities on inspiration, whereas there is a greater flow in the upper extremities on expiration, the opposite will occur. In the standing position, the return of flow from the legs is facilitated by properly functioning calf muscle pump mechanisms and valves. Thus, the calf muscle pump, when working properly, is to the veins, as the heart as a pump, working properly, is to the arteries. In respect to normal dynamics of the muscle pump mechanism in a normal limb, we can see at rest that normally blood flow will be in an antegrade fashion. We can see the perforating valves will be closed, and so therefore the flow will go into the superficial venous system into the deep system. With contraction, we can see the flow again into the superficial system to the deep system in an antegrade fashion. And on relaxation, we can see that the flow is antegrade, although the perforated valves will be open, which allows a little blood flow in this situation in a normal limb with normal muscle pump mechanisms. In an abnormal example, we can see here the dynamics of the muscle pump mechanism with primary varicose veins. With primary varicose veins, the problem is going to be in the superficial veins, in the valves of the superficial veins. So as we can see here at rest, and in contraction, we can see we have antegrade flow. However, in relaxation, we can see that we're getting a leakage or retrograde flow back, and as a result of that, the retrograde flow may lead to venous hypertension, which also may create further problems with respect to pathology in the lower extremity. With respect to pathogenesis and pathophysiology, Virchow's triad was actually discovered by Virchow over 100 years ago. It consists of stasis, vessel wall injury, and hypercoagulability. All of these factors lead to the risk factors that we can explain to be causing clots. In the clotting system in our body, there's a tug-of-war that goes on of increasing clotting and of also lysing of the clots. In the situation where we develop RDBT, the increasing clotting overrides this lytic mechanism, and that's consistent and related to things that cause stasis, for example, such as immobility in a hospitalized patient. In that setting, the coagulation factors will stay around longer and therefore increased clots will form. In respect to vessel wall injury, as we talked about before, we can affect the endothelial cell layer and therefore affect our antithrombotic layer, and as a result, we'll have an increased risk of clotting, such as you might see in trauma patients and or orthopedic patients, etc. The hypercoagulability type of patients are patients that have higher risk of clotting, whether this be a genetic modality or hormonal, etc. The origin of the thrombus that we talked about previously varies in size. It forms in the medium-sized veins, usually in the calf, and it begins as sort of a microscopic nidus, and then it grows. This clot, as you can see in the diagram here, can start and can potentially grow into a totally occlusive clot or a non-occlusive clot. This clot may remain small, remain large, and cause more havoc and more pathology in the leg and more swelling in the leg, or the possibility exists that this clot actually may flip and cause the potential of life-threatening pulmonary emboli. With respect to the major risk factors related to Bertschow's triad, we know that this can occur in patients over 40 years of age. There's a higher risk in those patients. There's a higher risk in patients where there's a personal family history of blood clots. A higher risk, especially in patients that suffer or have had treatment for cancer, again related to hypercoagulability, certain blood diseases, being treated for congestive failure and circulation problems, that may create stasis, and as a result, again, part of Bertschow's triad, increase our risk. Patients who have had recent orthosurgery, as we talked about before, trauma related to the endothelial cell, and those who have had inherited clotting tendencies, such as the newly discovered factor V Leiden, prothrombin gene mutation, etc. DVT, it turns out, is more common in women who are pregnant, again, probably related to hormonal hypercoagulability, have recently had a baby in a postpartum state, certainly within about 4 weeks postpartum, are taking contraceptive pills, or are on hormone replacement therapy. If we understand the mechanisms, we can understand the signs and symptoms of DVT and PE. The mechanisms relate to obstruction, as we talked before about an obstructing clot. The potential of valvular insufficiency that may occur after the clot may affect the valves, and resulting, again, both of those may result in venous hypertension leading to pathology. There also, in the initial DVT, there is actually inflammation, inflammation around the vessel wall that will give you signs of erythema and tenderness, etc. And also there's the potential, as we mentioned before, of embolization. What are some of the signs of DVT? Well, as we mentioned, swelling. Again, the venous hypertension, by Starling's Law, may increase swelling in the leg. We talked about pain related to inflammation, tenderness, redness. This may be different from the mild ankle swelling. DVT usually affects only one leg. And there has been a sign in the literature which relates to the pain being worse on bending the foot upwards towards the knee called the Hohmann sign, which is really not a very reliable sign of DVT clinically. The problem is, with DVT, there may be no signs or symptoms. Sometimes the problems are only obvious when PE develops. Pulmonary embolism is rare, but can cause shortness of breath and chest pain. In severe cases, patients may collapse and die immediately. Thirty to fifty percent is the amount of death rate if it's undiagnosed, whereas if treated immediately, that goes down to a significant three percent or less. And therefore, with DVT and PE, we need urgent investigation and treatment. With respect to the diagnosis of DVT, because of the unreliability of our clinical evaluation of DVT, duplex ultrasound has emerged as the initial diagnostic test of choice. ♪ The standard treatment for DVT still remains anticoagulation. These are agents that are blood thinners that do not lyse the clot, but prevent the formation of new clot and thus prevent the progression of the clot. The most common ones and the most common way that we treat these patients are with heparin or low-microate heparins and then on to Coumadin when it reaches the therapeutic level. The listing here of anticoagulation presently is heparin, low-microate heparins, synthetic pentosaccharide in selected instances, and warfarin. With respect to thrombolysis, this is a pharmacological removal or dissolution of the thrombus. This offers rapid resolution and does and can preserve valve function. IBC filters is a mechanical interruption, and also ultrasound can be utilized in placing the filter and also to follow where the filter is placed and remains. Surgically, in respect to treatment, we have thrombectomy and the cable interruption, as mentioned previously. Treatment is conservative. Observation with follow-up scans, especially in the patients who may have CAF-DVT, in which we know that within a two-week period, if the clot has not propagated, that clot will probably stay, and also those are patients that we cannot use anticoagulation. In addition to that, elastic gradient stockings are utilized as a non-pharmacologic approach to conservative treatment in these patients. With respect to interpretation on B-mode imaging, in the normal situation, you will have compressibility with no clot, you'll have compressibility with probe pressure with no thrombocene. When seen, you will see normal valve motion and may see blood flow. As you can see on the cartoon here, we have a probe with the beginning of compression, and as you can see in the normal situation, since the vein is very compressible and collapsible, you see normal compression. Here you can see a normal compression in the right common femoral vein. As you can see here, there is a clot inside the axial iliac vein, and therefore we're not able to compress fully. We can only compress to the area where the clot is. Therefore, this is our consistent diagnosis of a DVT with abnormal compressibility with probe pressure. In respect to our interpretation, we can distinguish between an acute or more recent thrombus and a chronic thrombus. It is more difficult to distinguish the exact age of the clot in between acute and chronic, but there are some signs that we can utilize with respect to an acute versus chronic. They are such as lightly echogenic, poorly attached to the wall, spongy texture to the clot, dilated vein, smooth borders. In the chronic thrombus, more we would see brightly echogenic, well-attached, rigid texture, contracted vein, irregular borders, and collateral veins. As you can see here, this is an example of a clot which has a tail, as noted here, with blood flowing around this tail. This clot here, as you can see, has a tail portion moving up and down that is unattached. Also notice there is somewhat of a smoother border here, although that is not always the most accurate way of telling about an acute clot. But in addition, there is a smooth border. There is some movement. There is a tail here that is not inherent, and certainly this is consistent with an acute thrombus. We become very concerned about this acute thrombus because this will have a greater risk of causing that potential life-threatening pulmonary embolism. This is an example of a very unique case in which we have an isolated chronic thrombus in a deep femoral vein. If you notice here, there is good flow around this area, which almost fills in completely. We notice that it is hyper-ecogenic, and we also know that this is very irregular, and thus this is consistent with more of a chronic thrombus formation. With respect to the Doppler examination or interpretation, we have phasicity, that is, flow that waxes and wanes with respiration. In the normal examination, we will have normal phasic flow that varies with respirations. We can see here in the abnormal Doppler examination, we lose the phasicity of flow and have more of a continuous flow signal, which implies some form of obstruction which can be secondary to a very significant clot. The remainder of the Doppler examination will show a spontaneity, that is, flow is present without need for prerogative maneuvers, the absence or presence of reflux, which may relate to valvular insufficiency, augmentation, increasing the flow with distal compression, and a valsalva maneuver, where, as we know from the low extremity, flow should cease with the valsalva. When we do these examinations, we may find some incidental findings which actually are similar to the differential diagnosis of the signs and symptoms that these patients have when they present to us. In respect to the avascular, we can have cysts and hematomas, which are the most common, congestive failure, lymphedema, cellulitis, abscess, lymphadenopathy, and or tumors. The vascular side, aneurysm, fistula, and significant arterial disease, atherosclerotic or non-atherosclerotic. These are excellent examples of a Baker's cyst. As you can see here, being hypoecogenic, these are avascular. In addition to that, we have a shot here, which shows sort of a wider shot, which can show us the, with this particular view, we can see the extent of the Baker's cyst, or this popatial cyst, that may extend below the knee into the upper calf. As in everything else, there are some pitfalls in our interpretation related to technical dependence, anatomic variation, obesity, edema, acoustic shadowing, and chronic DVT, which may blend into the surrounding tissue, making it difficult for us to interpret this. Let's get into the scanning. Again, all of your scanning should be done per your vascular laboratory protocols. So what I'll be describing here today really are general guidelines. You really need to tailor these to what you're doing in the lab, but these will be really some minimal requirements. Again, here's your transducer. We're using a 5 MHz transducer. It typically allows for visualization of all the vessels of interest from the level of the groin and down to the ankle. We'll take a little bit of gel and apply it to the transducer. And another important thing, what I forgot to mention, is you really need to have the patient's leg positioned properly in order to visualize all the vessels of interest. Now, most of the action will be happening on the medial aspect of the leg. One thing that we didn't mention during the guidelines is that in addition to looking at all the vessels of interest, it's also important to look at any specific areas of pain that the patient is complaining about. You don't want to look at the whole venous system and exclude DVT, but not look at some portion of the anterior calf where the patient has some specific complaints of pain. So this is what we'll do. We'll have the patient bend his knee a little bit, and then kind of just drop the leg towards you. And this gives you access to all of the vessels of interest from the level of the inguinal ligament and all the way down to the ankle. You want to take your transducer now, and in a transverse orientation, at the level of the groin, right in the femoral crease, just place your transducer right in here and identify the common femoral vein and artery. And this is a transverse shot that I'm looking at now. You'll note that the common femoral artery is to my left and the common femoral vein to the right. Now, typically what I would do at this level is just do a quick what I like to call a scout compression, just make sure that everything is okay. You want to make sure that you look at the lumen of the vessel for the presence of any echoes that might be representative of thrombus. You don't want to be doing a lot of compression in a patient who has thrombus within the femoral vein. At this point, typically what I do now is just start to work my way proximally and follow that vein as far up as I can. And you'll notice that the vessel is not as well visualized at this level, and that's because it starts to take a dive into the pelvis. So what I do typically is you'll note that I'm taking my transducer now, and I'm kind of angling it now corded or toward the feet. That gives you a more perpendicular approach to the vessel. It's much easier to visualize, and it also allows for better compression of that vessel. Again, once I follow it up, I follow it up all the way as far as I can, I'll start to do my compressions now. And you'll note now that as I press, it doesn't take a lot of pressure. The idea here is to press and to make sure that those walls touch. And this takes, it's not so easy as you might think it is. It really does take good technique. Poor compression technique is one of the pitfalls. Now, there will be some areas along the segment of the venous system that are naturally very hard to compress or may be incompressible just because of the surrounding anatomy. That doesn't usually happen at the common femoral vein, but note as you look at the ultrasound image here, I'm releasing the pressure here really at the level of a valve, and now I'm starting to push down. Those walls come together, the vein disappears, but the artery does not. The artery remains pulsatile. Now, what I'll do is I'll work my way down the common femoral vein to the level of its bifurcation. Here's the saphenal femoral junction. Now, I'm just doing compression maneuvers about one to two centimeters length at a time. Again, here's a compression. Now, the compression, the femoral artery has already bifurcated. I'll show you that again. Note the bifurcation of the femoral artery. The femoral vein will typically bifurcate just below this level, the common femoral vein, that is. So here we go, and you'll note just right there at that level, the common femoral vein has divided into the deep femoral and the femoral vein in the thigh. Now, once I've evaluated the whole length of the common femoral vein, I'm just going to freeze my image now. What I do is I go back now, and in the long axis, I start to assess the vein for flow dynamics, and this is important because the flow dynamics at the level of the common femoral vein can give you indirect information about what's going on above and below it, and there will be certain provocative maneuvers that you want to perform at this level. So here we are. Here is the saphenous vein, and you can see that here on the screen, and here to the left of it, or proximal, left is always proximal, you see your common femoral vein. Now, once you acquire a good image, here's a nice image of the common femoral vein, you just put your Doppler on, steer it appropriately, and you can hear the venous flow here. See, most of that flow is below the baseline. Now, there are a couple of things you can do when you're here. The first thing I like to do is just push on the belly, just have you move your arm here, and pushing on the belly really should result in cessation of flow, sometimes a little bit of flow reversal. So let's just take a peek at that. As I'm pushing down, you see there's a little bit short duration of reversal of flow, but then really cessation. Then when I release it, you should get a nice augmentation. And that really is a normal response to a proximal compression. The other provocative maneuver you can do here, and this really is a little bit dependent on the patient, is you can have the patient do a Valsalva maneuver. So what I'm going to ask you to do is just take a deep breath and bear down. And again, you see that cessation of flow, a short duration of flow reversal. Then as he resumes his breathing, you can see that the flow resumes. Again, that's a normal response to Valsalva's maneuver. Now let's take a quick look at what the normal flow pattern should be. So those are normal responses to provocative maneuvers. Now let's take a quick look at what a normal flow pattern should look like. Now the things that we like to look at, as we noted earlier, are phasicity, or that is that the flow should wax and wane with the patient's respiration. And that's demonstrated very nicely in this waveform. You can see there a little bit of flow reversal. Then a resumption of flow, cessation of flow, flow reversal. Very normal. This is a nice, normal response to the patient's breathing. One thing I want to note while we're here is that, especially in patients where you're doing a unilateral examination, you should always go to the contralateral side and assess the flow dynamics in the contralateral, common femoral vein, looking for things, for asymmetric flow changes. Then based on the changes, you need to make a determination about whether you think there may be cloudy, the proximal, or distal to the site that you're looking. In this patient, for instance, if I had seen a continuous waveform here, a contralateral to a normal flow waveform on the left, that really should prompt me to look at the iliac veins to exclude either a thrombotic process or some kind of a compression syndrome that could be affecting the flow. So let's just add a little bit of gel to the transducer. What I'll do now is I'm going to pick up at that spot. Actually, there's one other thing that I want to do in terms of a provocative maneuver. Let me just get a nice image of that femoral vein again. Again, here's your pulse wave signal. The other thing you can do is you can do distal augmentation. Simply by squeezing anywhere distal to the level of the transducer, such as I will do right now, you should get an augmentation of flow. I'll do that again. Let's take another quick look at that. Again, here's your femoral vein, your common femoral vein. Put your pulse wave Doppler on. Place your sample volume. Let's squeeze. You can hear this as well as see it on the screen, but listen to this. That's a normal response to distal augmentation. In the absence of that response, you really have to be highly suspicious of some type of obstruction in between where you squeeze the leg and where your transducer is. The opposite, however, may not necessarily be true. The presence of that augmentation does not necessarily exclude the presence of thrombus. You could always have some partial obstruction in between those two sites. It's nice to know that you have flow, but it doesn't absolutely exclude the presence of thrombus when you see that augmentation. A better sign is lack of augmentation. That's useful in patients where you can't, for whatever reason, visualize a particular area. Again, let's take it back now to the level of the inguinal ligament. What I'll do now is once I've completed this part of the examination, typically I like to break this examination down into three separate zones, the first one being the proximal part where you look at the external iliac vein, the common femoral vein down to its bifurcation and do the flow dynamics, second part being the evaluation of the thigh and the popliteal vein, and then zone three where I look at the tibial veins. Let's go back now. What I like to do is just pick up where I left off. Again, here is the sapheno-femoral junction, and I'll do my compressions. One other thing that I didn't note and that you haven't seen me do is that you really should be annotating as you're doing this. All of those images properly should have been annotated, should have said right, common femoral vein, with or without compression. Sometimes some of these ultrasound equipment have the capability of doing split-screen images. You can take a normal image at rest. As a matter of fact, let me just show you what that looks like. Here we have at rest this split image, normal. You can go and freeze that, go to the other side and push down again, do your compression, freeze the image, so that what you'll see here is the artery and the vein under normal conditions and then the artery and the vein with compression, and that would be normal. It's nice technology if you have it. Here we are again, and I'll work my way down now from the level of the sapheno-femoral junction. Again, compressing every one to two CMs. Here we are now in the femoral vein. Again, every one to two CMs, observing both the ability to compress the vessel as well as looking within the lumen of the vessel for the presence of echoes that might represent thrombus. Now, the inability to compress that vessel could be due to one of two things. Either you're using poor technique or there's thrombus within the lumen of that vein. So again, I'm just going to work my way down the length of the femoral vein, and you can see if you look at my hand here, I'm just a very easy compression every one to two CMs. Now, as you get to about this level, the distal two-thirds of the thigh, what you'll note is that the femoral vein starts to take a dive deep into the musculature. It can be hard to visualize, and it can be hard to compress. One of the things that you can do at this level is, you know, this is the typical approach. Just work your transducer anteriorly for a better image. And this is a much better image, and as a matter of fact, it allows for a little bit of an easier compression. Or the other option is you can take your transducer. Note that I'm pointing this transducer pretty much perpendicular to the leg here. If you take a look at this, the transducer is pretty much at a 90-degree angle. The vessel is starting to take a dive deep into the musculature here, so what you can do is take the transducer and literally point it toward the head or cephalad. Now, that allows for a more perpendicular approach to the vessel, better visualization, as you can see on this image, and if you do a little bit of support with your free hand, a much easier compression. You probably don't feel that at all right now. Just a very easy compression. And what I'll do is from this approach, just work my way down as far as I can using a medial approach. Now, what I'll do when I pick up the rest of actually, we're in the above-knee popliteal vein here. If you think anatomically, the proximal two-thirds of the thigh is where the femoral vein is located. The distal third of the thigh is really the above-knee popliteal. So as a matter of fact, when I'm looking at this area, I'm really looking at the above-knee popliteal vein. I'm going to resume looking at the rest of the popliteal vein from a posterior approach, but what I want to do before I get there is assess the flow dynamics in the femoral vein. So after having assessed it for my ability to compress it, I'll then just go and get a long-axis image. And again, I can use the color or I can use a spectral Doppler. I'm just going to use spectral Doppler here for a second. There's the artery. Steer this appropriately and place it within the lumen of the vein. And again, nice, normal flow dynamics. We're just going to squeeze this calf here. And again, we're getting a nice, normal augmentation of flow with calf compression. Let's just do that one more time. There you go, nice and normal. We can freeze this image. Now, what I'm going to do now is I'm going to use a posterior approach to examine the balance of the popliteal vein. So from the back of the leg here, I'm just going to ask you to bend your knee just a little bit. That's fine. We can find here the popliteal vein and artery. And there it is. And what I'll do now is I'll start to work my way up the back of the thigh. Again, compressing one, every one to two CMs, making sure those vein walls touch. Until I get to the level, again, there it is, compression, those vein walls touch, that I left off from the medial approach. So again, scan medially to this level. Scan posteriorly up the back of the leg to that same level that you left off from the medial approach. It's what I call an overlapping technique, and that allows you to make sure that you've seen the whole length of the femoral vein. This is really feasible in most patients. You see, I would say probably 95% of the patients that you look at, you should be able to visualize the whole length using a combination of those two approaches. Once I'm done with the compression piece, I'll then go back and get a long axis image of the popliteal vein. And you want to assess, again, the flow dynamics in the popliteal vein. Now, one thing I did not mention earlier was one of the other characteristics of flow within the femoral vein is the presence, is the ability to elicit flow within it without the need for a provocative maneuver. That's called spontaneity. And you should always have that in the common femoral vein, and you should almost always see that in the femoral vein in the thigh. Now, you may not always get that in the tibial veins, but you probably should see it in the popliteal vein. And we do have some spontaneous flow here. I'm just going to optimize this image a little bit because I want you to see that a little bit better. Here's a nice image. There's the popliteal vein. And what I'll do now, again, with my free hand, there's a compression and a nice normal response to a distal compression. You see the augmentation of flow. There it is again. And that's what you should see when you squeeze the calf, when you're trying to get that augmentation to happen in the popliteal vein. Again, more important with the augmentation is the inability to elicit flow than the presence of flow. Now, what I'm going to do now is I will scan the remainder of the below-knee popliteal vein. So I've scanned it from a medial approach above the knee. I've scanned it to about the level of the knee from the posterior approach. Now what I'll do is I'll scan it to the below-knee segment using, again, this posterior approach. And what I'm looking for is that level where the popliteal vein divides and becomes the perineal and the posterior tibial veins. And I know you're probably saying we don't do this often and you probably can't see it, but in fact you're going to see this in most of the patients that you scan. So let's try it. Again, here is your popliteal vein transversely. So I'm scanning, again, compressions every one to two cms, taking special care to make sure that those vein walls touch. There you go. They're touching. I'm working my way down into his proximal calf using a posterior approach. And right here you'll see that vessel bifurcate. You'll see one set of veins working its way toward the fibula. That will be in the bottom half of the screen. I'm just going to release the compression a little bit. And the other set of veins core syncs superficially to the tibia. Again, I'm going to work my way back. That's where they come together right here. Now I'm working my way distally, and this is where they divide. So that set of veins that works its way toward the fibula would be the peroneal veins. That other set would be the posterior tibial veins. So again, we're going to do the overlapping technique posteriorly. Now I'm going to go to the medial aspect of the leg. I'm just going to make sure that this machine is close enough to me so that I can operate it and still have access to the area of interest in his leg. So now, here we have a medial approach. I'm just going to add a little bit of depth here. And what you can see in this image here is both the peroneal veins. This is the fibula. Here are your peroneal veins. This is your posterior tibial vein. I'll compress them again from a medial approach. The vessel walls touch. I will then start to work my way proximally up, up, and compress, up, and compress, up. And you'll see that they join together to form the popliteal vein. So what I've done in this patient is I've confirmed that they're patent by compression using the medial approach from this way up, using a posterior approach from this way down. The overlapping technique gives you lots of confidence in terms of your ability to say that you've seen the whole length of those vessels. At this point, what I'll do now is we'll start to evaluate the calf veins. Now, a good way to do this, if you don't have a lot of experience looking at calf veins, is probably to go to the level of the ankle. Those vessels tend to be very superficial and much easier to see. So what we'll do is go right here just a little bit medial to the medial malleolus. I'm going to adjust my depth here. And you can see very easily in this image, right here, you have an artery and you have the two veins. And remember we said that for every artery below the knee, you should have at least two veins that accompany it. So here you can see in a transverse approach, I'm compressing the tibial veins right at the level of the ankle. Now, once I've identified this image, my job now is to move proximally. Again, compressing every one to two CMs at a time. There's a perforator vein that comes off right there, as a matter of fact. And at this level, there are about three or four vessels. Let's just put the color flow on and steer this. Now what I want to do is I will squeeze his foot. And you can see that as I augment, at least three or four vessels there have been filled by the color flow image. We have at least three or four patent posterior tibial veins associated with that tibial artery. But again, I'll work my way up. And I want to do that to the level that I left off when I was imaging those veins proximally. Here we are in the mid-calf. Just add a little bit of depth here. And I'll work my way up. There you go. And I'm happy now that I've been able to image all of the length of the posterior tibial veins. We're going to use the same technique to look at the peroneal veins. Now, in some cases, you may be able to, in this projection, see both the posterior tibial and the peroneal veins. But I would probably recommend, at least for the beginner, somebody who's not been doing this a long time, probably you should look at the posterior tibial veins first and then the peroneals. So here we are. One thing to keep in mind is that although the posterior tibial veins, again seen in this image up here superficially, will usually course all the way down to the level of the ankle, the peroneal veins you may not be able to visualize much past the level of the distal calf because they tend to terminate then to very small terminal branches. But if you look at this image here, you can see the peroneal veins at the very bottom of the image. And again, you compress it. Here's your peroneal artery. And as I release the compression, you can see the peroneal veins around it. And I will work my way proximally, again, to the level of the proximal calf. There's your compression. Here's your compression all the way up using this medial approach, making sure those vessel walls touch until I get to the level of the proximal calf, which is where I left off when I used the overlapping technique earlier. Now, I just want to give you a couple of techniques, a couple of tips, in terms of being able to identify the tibial veins because I have to say that there are a lot of labs out there that typically will only look at the veins from the groin to the knee. The reason a lot of labs won't do the tibial veins is because it does add significant time to the examination, and there is a little bit of a learning curve. There are a couple of tips you can use. One is to identify the vessels at the ankle because, again, they tend to be very superficial and easy to see there. The other thing you can do, and I've done in the past, is you can go to the mid-calf. You can find the bone right here. There's a little bit of a groove in this area. Just go here, turn your transducer transverse, put it down. In his case, we got a pretty nice image of the posterior tibial veins. But if you didn't see that, it takes a little bit of time for the eye to get used to recognizing the sonographic structures. You can just press a little bit. And what pressing does is that it accentuates the pulsatility of the arteries that are adjacent to the veins. And in this image, as I press down, I won't see the veins, but I can see a pulsatile tibial artery, and I can see a pulsatile peroneal artery. Now, as I release the pressure, you'll see that the veins show up. So there's one tip. The other tip is you can identify the bony structures. In this image, we see the tibia, and you can see that just immediately medial to that right here are your posterior tibial veins. So again, here's the tibia, and here are the tibial veins. And if I add a little bit of depth to this image, you can look for the fibula, which is right here. And immediately superior to that, or basically right above it, you can see your peroneal veins. There's your peroneal artery. And as I release the compression, those are the peroneal veins. And they're usually pretty close to each other. And then lastly, you can feel for that little groove, which is right in here. There's a little groove in between the muscle and the bone, which you'll feel here. You can feel that right there. You can literally just put the transducer right into that groove, and in many cases, you'll get a nice long-axis view of the vessels of interest. For instance, in this image, you can see the posterior tibial veins very nicely. And to prove that, I'll just show you by color. There is the artery. Once you've identified the artery, you can take the color flow off, turn your transducer transversely, and those are your posterior tibial veins. So those are a couple of tips in terms of finding the calf veins. One of the other things also to be aware of is that many patients will come in, and the most common indication for these patients will be pain and swelling. But I find that most of my patients, in fact, we have about a 10% yield for positive studies. That means they have some other cause for their pain. You want to be careful in terms of looking for things such as Baker's cysts, hematomas, other calf collections in the area where the patient's complaining of pain. Many times that can lead the patient to have other imaging procedures that might help the patient or at least explain the patient's symptomatology. The other thing you want to do is take a quick scan in the popliteal fossa. I'll just have you bend your knee a little bit again. Looking at the gastrocnemius veins quickly. You also want to go into the calf and take a quick scan of the calf looking for soleovanes. These are notorious sites for the formation of thrombus, de novo thrombus. So take a quick look in those areas. Commonly find things like Baker's cysts in the popliteal fossa. And then finally what I do is I go back up to the groin now, and I will look at the greater saphenous vein. We don't want to leave out the great saphenous vein. Great saphenous vein in the thigh, short saphenous vein in the leg. So you go up, and you want to look here. Again, we're at the level of the saphenofemoral junction, and you can see here in the image the saphenous vein taking off at that level. And you just, again, want to use the same compression technique. You want to use very light pressure. This vessel is very superficial. A lot less pressure within this vessel than you have in the deep veins, and it tends to compress very easily. So if you have any pressure at all, you may not be able to visualize this vessel. So you just want to work your way down. And in this case, the saphenous vein is relatively small, almost not seen, but again, very light pressure here. You can see it. Push down on it, and that vessel compresses very nicely. And work your way back up to the junction until you get to the level of the saphenofemoral junction. And you want to use that same compression technique from the level of the groin all the way down through the leg, looking at the entirety of the greater saphenous vein, the great saphenous vein. In our lab, our protocol calls for evaluating the first 10 to 15 CMs of the great saphenous vein. We don't usually look at the balance of the saphenous vein unless the patient has symptoms referable to the great saphenous vein distribution. One other technical tip before we leave is I'm going to have you put this leg down. I'm going to take a quick look at his left leg. An alternative way to look at the peroneal veins, you can actually have the patient bend his knee, put his foot flat on the bed. And then let's take a quick look at the peroneal vein. Just go right out here to the lateral portion of the leg. And you can see on the ultrasound image that the peroneal vein is very easily visualized from this approach. Matter of fact, those veins are huge. And again, very easily compressible around that artery. There's the peroneal artery. This is the peroneal vein. And again, you want to work your way distally, looking at the entirety of the vessel in the distal calf and work your way proximally to its confluence with the posterior tibial artery where it becomes the popliteal vein. And you can do that from this approach or you can do that from the medial approach. That is the evaluation of the patient with suspected deep vein thrombosis. And again, if you need more details, I'll refer you to the Society for Vascular Ultrasounds website. That's www.svunet.org. ♪♪♪

George Berdejo

Lower Extremity Venous Duplex

Professional Performance Guidelines

patient communication

deep vein thrombosis

diagnostic exam findings

exam time recommendations

continuing professional education

Mark Oliver

DVT

ultrasound examination process