Venous Evaluation

Lower Extremity Venous Evaluation Workshop William B. Schroedter, BS,RVT,FSVU

For this workshop I have included our protocol for lower extremity venous examination for venous thrombosis. We have evolved to have a somewhat different protocol for venous insufficiency. While this may be useful to you I would suggest that your first course would be to visit the Society for Vascular Ultrasound (SVU) website www.svunet.org There you can obtain the SVU’s “VASCULAR TECHNOLOGY PROFESSIONAL PERFORMANCE GUIDELINES” for Lower Extremity Venous Duplex Evaluation which was was prepared by members of the Society for Vascular Ultrasound (SVU) as a template to aid the vascular technologist/sonographer and other interested parties. It implies a consensus of those substantially concerned with its scope and provisions. It is extremely well conceived, thorough and refined and a great starting point for developing a protocol for your laboratory. I would encourage you to visit the SVU website www.svunet.org for a wealth of information on all aspects of non-invasive vascular testing. Become a member if you are not already, and maintain your valuable membership if you are. The second is from our laboratory. Please remember, the best labs create and refine a laboratory specific protocol that works for them and not try to directly copy someone else’s.

heavily on the clinical acumen of the technologists. The lower extremity venous exam may be ordered unilateral or bilateral according to patient symptoms and clinical assessment. If the clinical presentation suggests extension of the exam to the contralateral limb or the iliac veins, or inferior vena cava, this is performed and subsequently cleared with the referring physician. – Depending upon the indication for the exam, (Obstruction vs. Insufficiency) the focus of the exam will be different but we routinely perform a cursory assessment of valvular competency in the course of ruling out DVT and vice versa. – Generally, 7-4 MHz linear transducer is used for the large majority of the exam in most patients. The C42 curvilinear can also be useful in some patients where an acoustic window is difficult to obtain. If the iliac veins or the IVC are interrogated, the 4-2 MHZ curvilinear is employed. – Hard copy is a combination of video tape and still images. – With the patient in a supine reverse Trendelenberg position, begin by imaging the CFV at the groin. Observe color Doppler for spontaneity, phasicity, augmentation upon distal compression and release, and presence or absence of reflux. While usually easily discernable by color flow characteristics, a confirmatory spectral analysis should also be performed. Color flow pattern analysis should be done throughout the study in longitudinal planes. Spectral analysis confirmation of the flow state should be done in all vein segments and when dictated by color. Special attention should be given to Doppler angle, as it can be more difficult to heel-toe the transducer as that can cause the vein to compress and alter the flow patterns. Additionally, as velocity calculations are not as important to us in venous applications, it is vitally important to obtain a good Doppler waveform. The spectral analysis also allows the duration of reflux to be more accurately quantified. A valsalva maneuver should be performed in order to assess response to increased intra-abdominal pressure and presence of reflux with particular attention to the saphenofemoral junction and the confluence of the femoral vein. Instrument PRF should be in the medium to low flow settings for assessing reflux.

Quality Vascular Imaging Lower Extremity Venous Evaluation Protocol – Verify patient, order and indication for examination. – Explain test procedure to patient in order to minimize anxiety. – A complete history should be obtained from the patient including description of symptoms, including time of onset, duration and progression. Also, any other risk factors present, such as malignancy, chemotherapy, radiation, recent surgery, lack of mobility, etc. should be noted. – A physical exam should consist of observation of the legs noting any swelling, discoloration, mottling, ulcerations, varicosities, etc. Comparison is made to the other leg. Using the tape measure, the largest calf and smallest ankle measurements should be taken bilaterally and recorded on the patient record. – We routinely perform the examination according to the ordered test. This is highly significant for us being an independent facility, which is sometimes required to operate differently than a hospital or physician owned, office based laboratory. We rely

– The CFV, DFV, SFV, and GSV can be followed longitudinally looking for the presence of intra-luminal echoes and complete or partial absence of flow. Distal and, if indicated and possible, proximal aug-

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double/ bifid saphenous veins)

mentation maneuvers, should be performed to check for flow dynamics and/or reflux.

– Repeat on the contralateral limb if indicated according to the algorithm above.

– In a transverse view identify the saphenofemoral junction, CFV and check for compressibility by applying manual pressure with the transducer. The vessel walls must coapt completely. Continue down the CFV compressing at 1-2 cm intervals. Interrogate the CFV, Profunda vein for at least several centimeters, and SFV in their entirety. Watch for a bifid SFV. The gray scale image should be observed for intraluminal echoes. Be cognizant of a dominant profunda femoris system. This is usually seen best from a posterior approach with the patient positioned as described.

– Evaluation of the inferior vena cava/iliac veins - if indicated. This is not routinely performed in all patients referred to the lab to r/o DVT. If not urgent, this exam is usually performed after a fast in order to minimize bowel gas. – The patient is placed in a supine position and the exam is begun at the midline just below the xiphoid process. Abdominal exams generally require various acoustic windows and patient positions in order to optimize the data available from a patient. These vary from patient to patient depending upon anatomy, body habitus, recent (or even remote) surgery, and mostly the presence and location of bowel gas. Sonographer persistence is perhaps the most important requirement as gas can sometimes be moved by steady transducer pressure.

– Turn the patient on their side away from the leg being examined (Rt leg > Lt lateral). Provide support for the knee so that the patient can relax in comfort without the knee being flexed sideways. – Image the distal SFV being certain that its most distal segment imaged from the medial approach has been overlapped. Follow the SFV through the popliteal. The tibioperoneal trunk can be followed to its bifurcation from a posterior lateral approach. The PTV courses medially and will be lost behind the fibula. The peroneal runs more or less straight down the leg and can be seen in its entirety from this position. These vessels should be imaged in both longitudinal and transverse planes, assessing for obstruction and particularly flow dynamics longitudinally and for obstruction (transducer compression) transversely.

– The abdominal aorta is identified and then the IVC to the right. The IVC can usually be imaged from the right lateral side utilizing the liver as an acoustic window. Color and spectral Doppler are used to assess patency and direction of blood flow. Imaging can be used to detect partially obstructing thrombus. – The IVC is then followed distally to its confluence of the common iliac veins. Each CIV is followed distally noting the confluence of the internal and external iliac vein. The external iliac vein is then followed to the inguinal ligament. Color and spectral Doppler are used to assess patency and direction of blood flow. Imaging can be used to detect partially obstructing thrombus.

– The patient is returned to a supine position with care taken to prevent the calf muscle from being compressed from contact with the exam table. Usually an external rotation of the leg with a towel propping the knee is preferred. The distal PTV can be found at the medial malleolus and followed proximally to its origin. Often the peroneal can also be visualized for this approach as well. Similarly, these vessels should be imaged in both the longitudinal and transverse planes.

– If difficulty is encountered, the EIV can be located at the groin and followed proximally to the CIV and the IVC. In practice, both techniques are usually employed. – Venous recovery times (VRT’s) are not routinely obtained. However if indicated, the photoplethysmography (PPG) sensor is placed approximately 10 cm above the medial malleolus. After sufficient rest and a steady baseline is verified by the instrument, the patient is instructed to vigorously dorsiflex the foot. When maximum emptying is obtained by noting the instrument tracing, the patient is instructed to relax and the tracing monitored for refill. Calculations are made using the instrument and times are reported.

– The ATV can be visualized from an anterior lateral approach at the level of the tibial tuberosity as it arises through the interosseous fossa. It can be followed distally from here although the ATV's tend to be small and rarely thrombose. – On patients referred to us for evaluation of reflux and perforator vein incompetence the entire protocol is followed above to include checking the GSV, LSV, and any notable varicosities. This is initially performed with the patient in the reverse Trendelenberg position. If negative (no reflux) then the vein segments are also examined in the standing position. This allows for maximal vein expansion and therefore aids in identification of incompetent perforators. Distal compression maneuvers are employed in locating the level of reflux. Spectral analysis allows for grading severity of reflux as explained above. Measurements of the GSV, LSV, and incompetent perforators are noted. Anatomical variants are also noted (i.e. LSV proximal junction,

– The room is then cleaned and trash properly disposed. The exam table, instrument(s), including control panel and transducers are cleaned and/or sterilized as necessary with appropriate cleaner(s) when finished with exam. Paper linens are replaced in preparation for the next exam.

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