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Lower limb veins color and spectral Doppler ultrasonography examination. An examination protocol

Ann. Ital. Chir., 79, 4, 2008 273

Ann. Ital. Chir., 2008; 79: 273-280

Athanasios N. Chalazonitis*, Nicolas Condilis**, Joannie Tzovara***, Nikolaos Ptohis*, Fotios Laspas*, Ioannis Neofytou*, Eleni Feida****, Artemisia Tzannetaki****

*Department of Radiology, General Hospital of Athens “Hippocration”, Athens, Greece.**General Practitioner, Department of Familiar Medicine, 6th Municipal Health Center of Athens, Greece.***Department of Radiology, “IASO” General Hospital, Athens, Greece****Department of Radiology, General Hospital of Athens “Alexandra”, Greece

Equipment Settings

In the pelvic region and the adductor canal, linear-arraytransducers (ranged 3.5-5MHz) should be used usuallycompressed over the area of interest in order to providebetter depth resolution. For the limb, linear broadbandtransducers (ranged 5-7.5-10MHz) are preferred, becausethe examined veins are superficially located. As a rule the examined vein must always be in the cor-rect focal zone and Color coding and spectral parame-ters have to be adjusted properly to obtain optimal imagefindings. Because of the relatively slow venous flow,velocities ranging from 20 cm/s to less than 1 cm/s mustbe used. Flow direct toward the heart should be adjust-

ed to indicate an upward deflection. Low color wall fil-ter (50 to 100Hz) will give the best visualization of thecolor flow by avoiding wall and/or tissue motion. Colorgain must be low enough to prevent acoustic noise sono artificial flow can be depicted outside the vein, whileat the same time bright color flow should be seen insidethe vein. Color box (or window) must be adjusted inposition and size exactly for the region of interest. Otherwise, by unnecessarily increasing color box width,the frame rate decreases. Beam steering allows the oper-ator to direct the color flow beams at a preset angle.Ultrasonographic beam-to-flow angle, according to theDoppler formula, must be between 00 and 600, in orderto maintain reliable Doppler measurements. Angle cor-rection should be applied in order to determine flowvelocity, and must be kept at approximately the samevalue when following the course of an axis, in order toproduce quantitative measurements. Sample volume mustbe as small as possible and always in the center of thevein. Aliasing can be avoided by increasing pulse repe-tition frequency (PRF), or by lowering the baseline 1.

Pervenuto in Redazione Marzo 2007. Accettato per la pubblicazione inLuglio 2007.For corrispondence: A.N.Chalazonitis MD, PhD, 43 Thessalias str.,15231 Chalandri, Greece, (e-mail: [email protected])


Lower extremity’s venous pathology was traditionally investigated by intravenous venography. Nowadays Color Dopplerflow imaging is widely accepted as a well established, noninvasive method for the evaluation of deep pelvic and lowerextremity’s venous system. The vast majority of authors conclude that the method can safely replace diagnostic venogra-phy in all patients with venous thrombosis, thrombophlebitis and valve or communicating veins insufficiency.Optimal performance of Color Doppler flow imaging as a diagnostic tool for the whole lower limb veins requires:– proper equipment specifications and settings – knowledge of regional venous anatomy – established examination protocols– evaluation of morphological and functional findings– documentation of the findings.All these steps are described as a sequence of guidelines, photographs and multiple ultrasonographic images. Our papercan be useful to all physicians or sonographers involved with color Doppler studies for the evaluation of lower limbvenous diseases and abnormalities.

KEY WORDS: Color Doppler, Ultrasonography, Veins.

CASI CLINICI, SPERIMENTAZIONI, TECNICHE NUOVE

Lower Extremity Venous Anatomy

Deep Venous SystemDeep veins of the leg and pelvis accompany the arter-ies and have the same name as the arteries 1.

Peripheral levelDorsal veins of the foot as well as the medial and lat-eral plantar veins form the deep venous system thatdrains blood from the foot to the leg. These veins areconnected to the superficial root. Anterior and posteri-or tibial and peroneal veins form the deep venous sys-tem of the lower leg. Each venous system is composedof two veins running along either side of the corre-sponding artery finally forming a main trunk, calledthe popliteal vein either distal to the knee joint (in46% of cases), at joint level (in 13% of cases) or prox-imal to it (in 40% of cases) lying superficial to thepopliteal artery. After the popliteal vein enters the adductor canal it becomes the superficial femoralvein 2.Two groups of veins that are classified as belonging tothe deep veins are the gastrocnemic and soleal veinsand these are embedded in the gastrocnemius and thesoleus muscle respectively, and ultimately join thepopliteal vein. They are particularly important from aclinical perspective due to their tendency to form local-ized thrombi 2.

Thigh levelThe superficial femoral vein continues through the thighand joins the deep femoral vein 2-7cm below theinguinal ligament. From this point it is called the com-mon femoral vein and lies medially to the correspond-ing artery. A normal unpaired form of this vessel is foundin 62% of cases and a completely paired superficialfemoral vein occurs in only 3% of cases. In 21% of cas-es there is a division in the distal segment and in 13%of cases multiple veins are found. In patients with deepvenous thrombosis there is a high prevalence of dupli-cated femoral segments 1.

Pelvic levelAbove the inguinal ligament the common femoral veinbecomes the external iliac vein. The junction of the exter-nal ilac vein (which drains the lower extremity) and theinternal iliac vein (which drains the pelvic viscera andmusculature) produces the common iliac vein. It uniteswith the inferior vena cava at the level of the body ofthe fifth lumbar vertebra. Confluence of the two com-mon iliac veins occurs to the right of the spine. Shortlybefore origing the right common femoral vein, is crossedby the right common iliac artery. At this point the socalled “venous spur”, can form a membrane that pro-jects into the lumen and obstruct it. Evaluation of thespur is of great importance since it represents a poten-tial thrombogenic obstruction to blood flow 2.

Superficial Venous System

Great saphenous veinThe great saphenous vein originates from the superficialveins at the medial margin of the dorsum of the footand passes anterior to the medial malleolus to continueto the medial aspect of the leg. It joins the common femoral vein approximately 4cmbelow the inguinal ligament. This junction point is oftendilated into a funnel shape with its diameter measuringup to 2.0 cm.Approximately ten valves are encounteredalong its course and in 27% of cases it is paired 2.

Minor saphenous veinThe minor saphenous vein originates from the lateralmargin of the dorsum of the foot and passes dorsally tothe lateral malleolus and extends along the posterioraspect of the calf between the two heads of the gas-trocnemius muscle. It enters the popliteal vein usually atknee-joint level 3. The most common variant is for thevein to continue up to the thigh and enter the deep sys-tem or the great saphenous vein in the upper thigh 4.

Perforating VeinsThe deep venous system communicates with the super-ficial venous system through the perforating veins.Normal flow of blood is from the superficial to the deepvenous system. This happens when the calf muscles relaxand the pressure in the calf deep veins drops below thatof the superficial system. The valves open allowing theblood to flow from the superficial to deep veins. Thisfunction empties the superficial system and fills the deepveins. When the muscles in the calf contract the perforatingvalves close and blood flows from the high-pressure calfinto the lower-pressure popliteal and superficial femoralveins. Reverse flow is impeded by the valves of the per-forating veins 5.Dodd veins at the medial distal thigh are the most clin-ically important perforating veins. At this point they con-nect the great saphenous vein to the femoral vein. Alsoimportant are the Boyd (proximal lower leg) veins thatare found inferiorly and medial to the knee joint. Finally, Cockett (distal lower leg) veins that lie above thesole of the foot connect the great saphenous vein withthe posterior tibial veins 2.

Examination Protocol

A brief history is taken to define symptoms, previoussurgery and relevant risk factors. The examination isstarted with the patient in the supine position and witha slight elevation of the upper body in the elderly 2,3.Initially the external iliac vein is identified at the groinabove the inguinal ligament. The examination continu-

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Ann. Ital. Chir., 79, 4, 2008 275


tor canal until the distal part of the superficial femoralvein is seen. Then compressibility of the popliteal veinin transverse section is confirmed (Fig. 5). It is important to check for popliteal and superficial veinduplication in order to evaluate possible deep venousthrombosis in one channel only of a duplicated system2. Proceeding distally, the division into the three lowerleg veins occurs. It is important to evaluate these veinsbecause asymptomatic high-risk patients usually havesmaller and often non-occlusive thrombi frequently iso-lated to the difficult to visualize calf veins 7. A seatedposition is preferred for improved display of the calfveins, although the supine with head raised position isrecommended for elderly patients 2. The posterior tibialvein is located along the medial aspect of the leg andcan usually be found at the level of the medial malleo-lus. It is scanned cranially to its junction at the tibialtrunk (Fig. 6). From the same medial approach from where the poste-rior tibial vein is seen, the peroneal vein can be seentoo, but deeper in the scan plane (Fig. 7). Peroneal visu-alization sometimes requires a more posterior approach,as it lies on the “stocking seam” of the leg. The anteri-or tibial vein is best visualized from an anterolateralapproach (Fig. 8) with the transducer positioned betweenthe tibia and the fibula 5. Using the corresponding arter-ies as guiding landmarks these veins are examined alongtheir course with longitudinal and transverse sections,with and without compression. Their bifurcations shouldbe also imaged 1,3. Blood flow is generally not sponta-neous in the calf veins, and flow must be augmented byperiodic manual compression of the foot or the lowerportion of the calf 5.When symptoms suggest superficial vein thrombosis,great saphenous and small saphenous vein should beexamined in detail with the patient standing 1-3. These veins are followed along their anatomical courseand their patency is checked with transverse compres-

Fig. 1: Probe positioning along course of the common femoral vein. Fig. 2: Probe positioning in the groin. Common femoral vein is identi-fied directly medial to the common femoral artery.

ous in a cranial direction, with long axis imaging untilthe vessel dives deeply into the pelvis (Fig. 1). Until thislevel the vessel can be well displayed and be easily com-pressed. From this point the transducer is located later-al to the rectus muscle and the external and commoniliac veins are followed with the goal of tracing the ili-ac system all the way to the inferior vena cava. 1,3 Patencyof the iliac veins is usually assessed indirectly by usingpulsed-wave Doppler assessment of the common femoralvein blood flow pattern 5.In a transverse plane in the groin the common femoralvein is identified directly medial to the common femoralartery (Fig. 2). The course of the vein is followed cau-dally in order to find two important landmarks: the greatsaphenous vein and the junction of the superficial anddeep femoral veins. At this point patency of the deepfemoral vein should be confirmed. The common femoralvein is examined in detail; transverse compression is usedfor checking the patency (Fig. 3) and a Doppler spec-trum is used for the evaluation of respiratory fluctua-tions during a Valsalva manouver 3.Evaluation of flow in the common femoral vein and theValsalva response are used to exclude thrombosis of theiliac veins or the inferior vena cava 5. Next the superfi-cial femoral vein is followed all the way to the adduc-tor canal. A full length of the vein must be sampledwith images parallel to the vein and patency of the ves-sel must be checked by transverse compression at approx-imately 2cm intervals 5. The adductor segment of thesuperficial femoral vein is too deep to be effectively com-pressed in most patients, so It is useful to compress thevessel with a hand underneath the lateral thigh duringthe examination, or to use color Doppler imaging 3,7.Evaluation of the popliteal vein can be achieved withthe patient placed in a prone position (Fig. 4) withhis/her ankle slightly elevated and supported suitably.The popliteal vein is imaged at the posterior aspect ofthe knee. It is followed upward all the way to the adduc-


276 Ann. Ital. Chir., 79, 4, 2008

sion. Valvular competence is evaluated with Valsalvamaneuver or compression at a more distal level 3.Perforating veins are usually examined in their typicalanatomical location (Fig. 9) when there is a clinical sus-picion of their insufficiency. The contra lateral extremi-ty should be evaluated if clinically indicated 2.

Evaluation of Morphological and FunctionalFindings

General Ultrasonographic Normal and Abnormal VeinCharacteristicsIn a longitudinal section the venous lumen is anechoicand the interior surface of the vein wall is smooth. Thewall itself is so thin that it cannot be seen and no arte-rial pulsation can be seen. A patent vein lumen can be obliterated by a smallamount of extrinsic pressure. In cases of acute throm-bosis the thrombus can be recognized by its greater echointensity, although the lumen cannot be obliterated withcompression. Visualization of the thrombus itself is nota reliable sign however the echogenity of the thrombusis quite variable ranging from virtually anechoic to moreechogenic than muscle. Using color Doppler flow imag-ing, a thrombus is suspected by the absence of colorhowever sometimes color does not fill the vein becausethe equipment singular settings selected are not sensitiveenough to depict the slow blood flow. On the otherhand “overgaining” may cause color to bleed into sur-rounding tissue and may obscure partial thrombus 5. Themost important aspect of the venous evaluation is todetermine how the vein responds to compression by thetransducer 1,5. Lack of compressibility of the vein is perhaps the singlemost reliable finding for differentiating between throm-bosed and normal veins 1,3. Vein compressibility is bestchecked in a transverse section because a false impres-sion of compressibility may occur with long-axis viewsas the vein may slip out of the image 3. In the case of

acute thrombosis the vein is substantially larger than thecorresponding artery (because thrombus distends the veinlumen) and there is not a visible modulation due to res-piration. This distending pressure is the source of someof the pain that is experienced by the patient with acutethrombosis. Venous size may also be increased by back-pressure from congestive heart failure or venous reflux.Enlargement shows therefore, once again not be the solecriterion for the diagnosis of venous thrombosis 1. Themajor veins of the thigh are somewhat larger in diam-eter than their corresponding arteries and their size varieswith respiration. Also the diameter of large leg veins increases with res-piration. However, veins with chronic deep venous thrombosistend not to be dilated, may have irregular channels, col-or-encoded blood flow within the lumen, and will oftenhave thickened, poorly compressible vein walls (even ifthe lumen is completely recanalized) 7.

Fig. 3: Junction of the superficial and deep femoral veins.

Fig. 4: Evaluation of the popliteal vein can be achieved with the patientplaced in a prone position.

Ann. Ital. Chir., 79, 4, 2008 277


Doppler Characteristics and Diagnostic MannipulationNormal venous flow is phasic (Fig. 10) and the velocityof flow changes in response to respiration. Expiration caus-es an increase of venous flow in the lower limb, while analmost complete cessation of blood flow follows in thelate respiratory phase (Fig. 11). On occasion, loss of thisnormal respiratory change may be due to low blood vol-ume or increased right-sided heart pressures 1.However, many times a continuous flow will indicate thepresence of substantial obstruction proximally, or some-times distally, to the site of Doppler examination. A pha-sic pattern may persist when thrombus does not sub-stantially obstruct the vein lumen;3 therefore the identi-fication of a phasic flow pattern does not exclude throm-bosis entirely but only excludes thrombus that occludesthe vein lumen. After the obstructed segment is local-ized and checked with compression, presence or absenceof blood-flow signals may be interrogated with colorDoppler.Manual compression of the extremity distal to the site ofthe examination increases venous flow (Fig. 12 a-b). Thisresponse (signal augmentation) confirms substantial paten-cy of the veins between the site of Doppler examinationand the site of venous compression. Proximal compressionis used to check valvular function. Sufficient valves pro-duce a cessation of blood flow during compression. Thismaneuver is used mostly for the calf veins 2.Valsalva manipulation is principally used to documentthe sufficiency of valves of thigh veins. Deep inspirationfollowed by bearing down increases thoracic and abdom-inal pressure and can result in an abrupt cessation ofblood flow in large and medium-sized veins. Theresponse profile documents the patency of the venoussystem and is particularly useful whith segments that can-not be directly examined 2,3. Loss of normal responsemay be secondary to either acute vein thrombosis orextrinsic obstruction of the iliac venous system (pelvicmalignancy or pregnancy) 5. Valvular incompetence isdiagnosed by demonstrating retrograde flow in responseto the Valsalva maneuver.

Fig. 5: Compressibility of the popliteal vein should be confirmed in trans-verse scan.

Fig. 6: Posterior tibial vein is located along the medial aspect of the leg.

Fig. 7: Peroneal vein can be seen too, but deeper in the same scan planefor the posterior tibial vein.

cient valve of the perforating vein toward the surfaceand approaching the probe 2.

Documentation

All images taken should be marked with the examina-tion date, patient identification, image location andprobe orientation. For the documentation of the normalleg veins, an attempt should be made to evaluate the fulllength of the distal inferior vena cava, femoral, poplitealand calf veins as well as the great saphenofemoral junc-tion and the proximal segment of the great saphenousvein. Images, with and without compression should berecorded at each of the following levels:


278 Ann. Ital. Chir., 79, 4, 2008

Fig. 8: Anterior tibial vein is best visualized from an anterolateral approachwith the transducer positioned between the tibia and the fibula.

Fig. 9: Typical anatomical location of perforating veins.

Fig. 10: Normal venus flow Doppler characteristics.

Fig. 11: Expiration causes an increase of venous flow in the lower limb,while an almost complete cessation of blood flow follows in the late res-piratory phase.

When venous valves are insufficient, flow fails to stopduring this maneuver and it has a centrifugal directionof varying duration. During the Valsalva maneuver a blood flow reversal ofless than 0.5 second is normal and related to the timerequired for valve closure. Blood flow reversal of greaterthan 0.5 second is suggestive of valvular incompetence,whereas flow reversal exceeding 2 seconds is definitelypathologic.7When testing the sufficiency of perforating veins thepatient is seated in an upright position and a tourniquetis placed to compress and obstruct the venous flowthrough the epifascial veins. The tissue distal or proxi-mal to the tourniquet, is compressed. During the com-pression, venous flow is registered through the insuffi-

– common femoral– mid – femoral– mid – popliteal veins– saphenofemoral junctionAny other abnormality (e.g. lymph node, haematoma,pseudoaneurysm or other mass) should be document-ed.Areas of focal tenderness should be documented aswell.Documentation of an abnormal area anywhere in theleg venous system includes: location and length ofthrombosed lumens and Doppler flow recordings dur-ing deepened respiration, as well as during Valsalvamaneuver. A medical report must be made.

Conclusion

This review will provide assistance to practitionersperforming examinations of the lower limb venoussystem by the use of color and spectral Doppler utra-sonography. In our paper we describe the techniquefor the evaluation of the deep and peripheral venoussystem and we provide diagnostic criteria for detect-ing abnormalities that occur in these veins.

Riassunto

La patologia del tratto venoso delle estremità inferiorivenne tradizionalmente investigata con l’uso dellavenografia intravenosa. Oggi il doppler di flusso acolori è una tecnica diagnostica per immaggini lar-gamente accettabile per lo studio del sistema venosodella profondità della pelvi e delle estremità inferio-ri, in quanto come tecnica risulta essere non invasi-va, a basso costo e facilmente ormai ripetibile e repe-ribile nella maggior parte dei centri ospedalieri. La

maggior patre degli Autori infatti conclude che la sud-detta tecnica può sostituire la venografia, in modosicuro dal punto di vista della credibilità dei risulta-ti, per la diagnosi delle problematiche legate allatrombosi venosa, alla tromboflebite ed alla insuffi-cienza delle valvole venose o/e dei vasi venosi comu-nicanti. Per avere un risultato ottimale per lo studiodella patologia del sistema venoso dell’intero trattoinferiore del corpo dalla tecnica diagnostica per imma-gini del doppler di flusso a colori, occorrono i seguen-ti: adeguate specificazioni per l’uso e la messa a pun-to dell’equipaggiamento utilizzato buona conoscenzadell’anatomia del sistema venoso della regione corpo-rea che interessa studiare, uso di certificati ed accre-ditati, protocolli d’esame, buona valutazione deireperti morfologici e funzionali buona documentazio-ne dei risultati reperiti. Tutti questi passi vengonodescritti in questo articolo attraverso una sequenza diguidelines, di fotografie e di multiple immagini ultra-suonografiche. In questo modo pensiamo che il nostroarticolo potrà essere utile, quale punto di riferimen-to, a tutti i medici coinvolti all’utilizzo del dopplerdi flusso a colori, quale tecnica diagnostica perimmaggini, per la valutazione delle anormalità e del-le patologie del sistema venoso della parte inferioredel corpo.

References

1) Polak JF: Peripheral Vascular Sonography. A Practical Guide.Baltimore, Williams & Wilkins, 1992.

2) Hennerici M, Neuerburg-Heusler D: Vascular Diagnosis withUltrasound. Stuttgart: Theme, 1998.

3) Zwiebel W: Introduction to Vascular Ultrasonography.Philadelphia: W.B. Saunders, 2000.

4) Goldberg BB, Merton DA, Dean CR: An Atlas of UltrasoundColor Flow Imaging. St. Louis: Mosby, 1997.

Ann. Ital. Chir., 79, 4, 2008 279


Fig. 12: Manual compression of the extremity distal to the site of the examination increases venous flow (signal augmentation).

5) Needleman R: Peripheral Venous US. In: Rifkin MD (ed)RSNA Sylllabus: Ultrasound, RSNA, 1991; 201-10.

6) Jonson MS, Lalka SG: Role of US in the Diagnosis of PeripheralVascular Disease. In: Ferris EJ, Waltman AC, Fisman EK, Polak JF,Potchen EJ (eds) RSNA Syllabus: Vascular Imaging, RSNA, 1998;183-90.

7) American College of Radiology Standards. ACR Standard for the:Performance of Peripheral Venous Ultrasound Examination. ACR,Reston, 1997; 311-15.


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