Current methods in the diagnosis of deep venous thrombosis of the lower limbs

The diagnosis of lower limb deep vein thrombosis requires to use of complementary diagnostic tests. For a long time phlebography has been the only reliable examination and is always regarded as the gold standard by many people. In recent years, non invasive diagnostic modalities have been developed. Most significantly scintigraphy, plethysmography, color Doppler ultrasound and MR imaging. MRI is as reliable as venography but, at the present time, it is time-consuming and far less available than the other modalities. Scintigraphy and plethysmography may be useful but are less accurate and yield a somewhat higher rate of false positive and negative examinations. Color Doppler ultrasound has proved its effectiveness and is currently recommended as the diagnostic modality of choice. Venography is still a significant diagnostic tool for questionable cases or for technically inadequate Doppler ultrasound examinations.     

Diagnostic imaging in deep vein thrombosis of the limbs

The clinically suspected deep vein thrombosis (DVT) should always be confirmed by instrumental procedures. In fact, about 70% of patients with clinically suspected DVT are shown to be negative on instrumental investigations. Phlebography is still the gold standard in the diagnosis of peripheral DVT. Main phlebographic findings are: persistent filling defect; abrupt interruption of contrast in a vein; lack of opacification in all or some deep veins; flow diversion with opacification of collateral branches. At present, peripheral phlebography is performed when the other noninvasive exams (Color Doppler US and Duplex Doppler) are doubtful, technically limited or when thrombosis of innominate veins or superior vena cava, is suspected. Real-time US enables direct visualization of the limb proximal veins. The venous wall, the venous valves, the thrombus and its development, the anatomic variants, the perivenous structures which may impact on the normal physiology of venous return, are depicted. However, the distal veins of the leg and arm and deep veins (the iliac veins, the superficial femoral vein in the adductor canal) are not accurately visualized. The US findings in DVT include: the presence of echoes within the vascular lumen; the veins in axial scans are not compressible. Pulsed Doppler and duplex Doppler combine the morphologic and functional study. Injury caused by DVT at the valvular level (postphlebitic syndrome) is visualized. Primary deep vein thrombosis caused by valvular disorders (valvular aplasia) is identified. Inadequate superficial and perforating veins to be treated with surgery are mapped. Color Doppler US depicts directly superficial and deep limb veins combining the morphologic with the functional assessment represented by the visualization of the map of flow velocity and direction. Recently, a new diagnostic procedure, the color Doppler Energy (CDE) or Power Doppler has been introduced. Together with mean flow velocity and spectral variance, the signal energy or power is also analyzed. The CDE is independent of the US incidence angle, it does not shows the flow direction, detects particularly slow flows, early canalization of thrombi and non occlusive thrombosis. Color Doppler diagnosis of thrombosis is prompt because an area with absence of color is visualized. Collateral vessels and flow direction within them, is well depicted. Beside the site and extension of thrombosis, color Doppler US is able to directly visualize the distal end of the thrombus, which when floating is at high risk for embolism. CT allows an adequate study of the iliocaval axis and is useful if phlebography or color Doppler US are not diagnostic. Iliocaval thrombosis represents a not infrequent finding during abdominal CT. The thrombus appears as a hypodense mass encircled by the hyperdense rim of contrast medium.     

Ultrasound screening for deep venous thrombosis after total knee arthroplasty. 2-year reassessment

The efficacy of ultrasound compared with ascending venography for the detection of deep venous thrombosis immediately after total knee arthroplasty was assessed after a 2-year interval. One hundred thirty-seven patients were eligible for the study; however, 31 patients received only one of the screening methods and a color Doppler examination was inconclusive in six patients. Therefore, 100 patients had a Doppler examination and a venogram. Overall, the sensitivity of ultrasound was 85%, the specificity 97%, the positive predictive value 85%, the negative predictive value 97%, and the accuracy 95%. The sensitivity in the calf was 83%, in the popliteal vein 86%, and in the femoral vein 100%. Two years ago, the initial assessment of ultrasound for the detection of deep venous thrombosis after surgery in patients who had total joint arthroplasty revealed a 75% sensitivity, 99% specificity, 91% positive predictive value, 97% negative predictive value, and 97% accuracy. The sensitivity in the calf was 83%; the sensitivity in the popliteal vein was 40%; and the sensitivity in the femoral vein was 50%. After 2 years of using this screening test with one technician and one radiologist, an improvement with this noninvasive technique was shown. However, it was found that Doppler imaging is not as sensitive as venography for detecting calf thrombi. Any imaging technique should be validated by each institution to determine the validity of the instrument and the learning curve of the technician administering the examination.     

Sonographic incidence of deep venous thrombosis contralateral to hip or knee replacement surgery

PURPOSE: This study assesses the sonographic incidence of deep venous thrombosis (DVT) contralateral to and the venographic incidence ipsilateral to hip or knee replacement surgery and the role of sonography in routine surveillance. METHODS: We prospectively evaluated 178 consecutive patients with sonography of the femoropopliteal venous systems of the contralateral lower extremity and venography of the ipsilateral lower extremity on days 3 and 4, respectively, after total hip or knee replacement surgery. RESULTS: No cases of acute DVT and only 1 case of chronic DVT isolated to the popliteal system were identified by sonography in the contralateral extremity. In the ipsilateral extremity, venography identified 26 patients with acute DVT (3 femoropopliteal, 21 calf, and 2 concurrent femoropopliteal and calf). CONCLUSIONS: Routine sonographic evaluation of the lower extremity contralateral to hip or knee replacement surgery is not cost-effective because of the extremely low incidence of detectable acute thrombus.     

Minimally invasive cardiac surgery: current status and perspective

This study investigated the features of calf deep vein thrombosis (DVT) as a pulmonary embolic source. Fifty-eight lower limbs in 29 patients who were suspected of having DVT distal to the popliteal vein were screened by ultrasonography. Then, ascending venography was performed to confirm the diagnosis. Pulmonary embolism (PE) was diagnosed in suspected patients by use of pulmonary perfusion scanning or pulmonary angiography. Venography revealed calf DVT in 33 limbs in 28 patients. Of 28 patients, six had symptomatic PE. Thrombosis was found in the muscle veins in 18 limbs, the trunk veins in 11, and both veins in four. Isolated single vein thrombosis was found in the soleal vein in 14 limbs (42%), the posterior tibial vein in eight, the peroneal vein in two, and the gastrocnemius vein in two. The overall percentage of soleal vein thrombi was 61%. All six patients with symptomatic PE had isolated soleal vein thromboses. Calf DVT was a pulmonary embolic source when isolated thrombosis of the large soleal vein was more than 7 mm in diameter. Soleal veins were the most frequent and important location of calf DVT, suggesting that these were an occasional embolic source of critical PE.     

Comparison of immunofiltration assay of plasma D-dimer with diagnostic imaging in deep vein thrombosis

This prospective study was designed to assess the diagnostic sensitivity, specificity and negative predictive value of the NycoCard D-dimer plasma immunofiltration assay in patients with suspected deep vein thrombosis (DVT) confirmed by ultrasonography/venography. 84 medical patients were recruited: 43 patients (51%) had proven venous thrombosis, 33 by venography and 10 by ultrasonography. The sensitivity of NycoCard D-dimer in patients with DVT was 95.3%, the specificity was 22.0% and the negative predictive value was 81.8%. An algorithm including the NycoCard D-dimer test for the acute management of DVT is proposed. This would enable low-risk patients to be discharged early from hospital, without imaging or anticoagulant therapy.     

Role of radionuclide venography in the detection of proximal deep vein thrombosis: a prospective comparative study

The role of radionuclide techniques in the investigation of thromboembolic disease has been re-evaluated. Forty-eight patients suspected of having embolic lung disease (PE) or deep venous thrombosis (DVT) were studied prospectively and investigated with radionuclide venography and ventilation/perfusion lung scintigraphy. Thirty-two also underwent contrast venography and peripheral 99Tcm-labelled red blood cell scintigraphy. Both radionuclide techniques were compared to each other and against the 'gold-standard'. The overall agreement and disagreement rates were 89 and 11% for radionuclide venography and 88 and 12% for radionuclide blood pool venography. The overall sensitivity and specificity were 90 and 73% for radionuclide venography and 88 and 82% for radionuclide blood pool venography. The blood pool technique did not perform better than radionuclide venography which was valuable in the detection of DVT and confirmation of PE. Radionuclide venography appears useful especially in patients suspected of having PE and DVT.     

Diagnosis of venous thrombosis in the legs using 81Krm venography

Contrast venography, the accepted gold standard for the diagnosis of venous thrombosis of the leg, is a painful and invasive procedure with late side effects. There is controversy in literature reports about the sensitivity of 99Tcm-macroaggregated albumin (MAA) phlebography: indeed, using 99Tcm-MAA, poor results are obtained when one has to detect calf vein thrombosis. As with other isotopic procedures requiring a pedal injection of the tracer, the use of an injectable solution of 81Krm is a nonspecific method, based upon the abnormality in flow in the deep venous system which results from a deep venous thrombosis. However, when compared with 99Tcm-MAA, 81Krm offers theoretical advantages for phlebographic studies of the lower limbs. In this work 24 patients were studied both with contrast phlebography and with 81Krm. Although 81Krm provided images of high quality, there was a lack of sensitivity below the knee, where false negative results were observed. This could be explained by the fact that the radionuclide venographic procedures usually visualize only one or, in some cases, two of the three deep veins of the calf. Moreover, accurate differentiation between superficial and deep veins in the calf often appears difficult, even using a tourniquet.     

Distribution of thrombosis in patients with symptomatic deep vein thrombosis. Implications for simplifying the diagnostic process with compression ultrasound

BACKGROUND: Two different diagnostic strategies are used to perform compression (real-time) ultrasound for the diagnosis of clinically suspected deep-vein thrombosis. One is to examine the entire proximal venous system from common femoral to distal popliteal vein; the other is a limited examination of only the common femoral and the entire popliteal vein. The latter strategy, which is less time-consuming and requires less expensive equipment, is based on a strong impression from prospective studies using limited compression ultrasound that proximal vein thrombi always involve the common femoral or popliteal vein. This impression, which is supported by the demonstrated safety at long-term follow-up of not treating patients whose limited compression ultrasound is normal at presentation and then repeated within the next week, has not been tested in a formal study. Therefore, we reviewed a large series of venograms performed in consecutive patients with clinically suspected venous thrombosis to determine the distribution of venous thrombosis in symptomatic patients. METHODS: Venograms were performed using 150 mL of radiographic contrast material. Before the study, a panel of experts agreed on the standardized criteria for the assessment of venograms. Venograms were adjudicated blindly for the presence of deep vein thrombosis and to determine the distribution of proximal vein thrombosis and isolated calf-vein thrombosis, the size of proximal thrombi, and whether they were occlusive or nonocclusive. Subsequently, the duration of symptoms was related to the venographic findings. RESULTS: Five hundred sixty-two venograms from consecutive patients with a first episode of clinically suspected deep vein thrombosis were adjudicated. Of these, 20 (3.6%) were inadequate for interpretation. In the remaining 542, venous thrombosis was demonstrated in 189 instances (prevalence, 35%; 95% confidence interval, 31% to 39%) and were located in the proximal veins in 166 (88%; 95% confidence interval, 82% to 92%) venograms. Isolated calf-vein thrombosis was present in the remaining 23 (12%; 95% confidence interval, 8% to 18%) venograms. Proximal with concurrent calf thrombosis was detected in 164 (99%) of the 166 patients. Proximal thrombi involved only the popliteal vein in 16 (10%); the popliteal and superficial femoral veins in 70 (42%); and the popliteal, superficial, and common femoral vein in eight (5%); whereas thrombi involving the entire proximal deep venous system were detected in 58 (35%) venograms. Isolated thrombosis of the superficial femoral, common femoral, and iliac vein was not observed. Proximal venous thrombi were occlusive in 146 (88%) patients. No relation between the duration of symptoms and the extent or the occlusiveness of venous thrombi could be demonstrated. CONCLUSIONS: Most symptomatic patients have extensive occlusive proximal vein thrombosis at the time of presentation. Thrombi isolated to the superficial femoral or iliac vein were not observed in this large sample of consecutive patients. Our data support the use of the relatively simple, inexpensive, and rapid compression ultrasound method that limits the examination of the proximal veins to the common femoral and popliteal veins.     

The natural history of calf vein thrombosis: lysis of thrombi and development of reflux

PURPOSE: Although the fact is well accepted that deep venous thrombosis (DVT) of the iliac, femoral, and popliteal veins can lead to the post-thrombotic (postphlebitic) syndrome, the significance of isolated calf DVT on the development of late venous sequelae and physiologic calf dysfunction is unknown. The purpose of this study was to review the outcome of 58 limbs with isolated calf DVT and report the clinical, physiologic, and imaging results up to 6 years after the onset of DVT. METHODS: The study consisted of 58 limbs of 54 patients in whom isolated calf vein DVT was diagnosed between 1990 and 1995. Proximal propagation of clot, lysis of thrombi, and development of symptomatic pulmonary emboli were examined. Of the patients, 28 received anticoagulation therapy, and 26 did not, but they had follow-up with serial duplex scans. At late follow-up 1 to 6 years later (median, 3 years), 23 patients were examined for the post-thrombotic syndrome, and all 23 underwent clinical examination, color-flow duplex scanning, and air plethysmography. RESULTS: Proximal propagation of DVT from the calf veins into the popliteal or thigh veins occurred in 2 of 49 cases (4%) within 2 weeks of diagnosis. No patient had clinically overt pulmonary emboli develop regardless of whether anticoagulation therapy was received or not. The most common site for calf DVT was the peroneal vein (71%). Complete lysis of calf thrombi was found in 88% of the cases by 3 months. At 3 years, 95% of the patients were either asymptomatic or mildly symptomatic, and 5% had discoloration of the limb. No ulcers occurred. By air plethysmography, physiologic abnormalities were found in 27% of the cases, which was not significantly different from normal controls. Valvular reflux by duplex scanning of the calf vein segment with DVT was found in 2 of 23 cases (9%). However, reflux in at least one venous segment not involved with DVT was found in 7 of 23 cases (30%), which was higher than, but not statistically different from, normal controls, with reflux occurring in 5 of 26 cases (19%). CONCLUSIONS: Isolated calf vein DVT leads to few early complications (ie, clot propagation, pulmonary emboli) and few adverse sequelae at 3 years. The peroneal vein is most commonly involved and should be a part of the routine screening for DVT. Lysis of clot usually occurs by 3 months. Although valvular reflux rarely is found in the affected calf vein at 3 years, reflux may be found in adjacent uninvolved veins in approximately 30% of the cases. The question of whether this will lead to future sequelae, such as ulceration, will require longer follow-up.     

Renal vascular Doppler imaging: clinical benefits of power mode

Power Doppler ultrasound (US) is a new technology that is superior to conventional color Doppler imaging in the detection of blood flow. Because of its greater sensitivity to flow and reduced angle dependence, power Doppler US demonstrates optimal color filling of renal pedicular vessels and allows improved evaluation of the renal parenchymal microvasculature. Power Doppler US was used as an adjunct to conventional color Doppler imaging in technically challenging cases and to improve evaluation of renal vascular disorders in a series of 916 patients. The primary clinical advantages of using power Doppler US compared with conventional color Doppler imaging include better morphologic appreciation of atherosclerotic changes in the renal artery wall, allowing improved diagnostic performance especially in hemodynamically nonsignificant plaques; ability to differentiate between subocclusive renal artery stenosis and occlusion; increased confidence in the diagnosis of renal vein thrombosis and in the assessment of caval tumor thrombus; and better appreciation of renal cortical perfusion defects. In addition, because of its greater sensitivity to perivascular artifact, power Doppler US has the potential to increase the detection rate for intrarenal arteriovenous fistulas.     

Colour duplex ultrasonography in the rational management of chronic venous leg ulcers

Colour duplex ultrasonographic imaging has largely replaced venography in the assessment of lower-limb venous disorders. This is a study of the use of duplex in the management of patients with chronic venous ulceration in community ulcer clinics. Patients with chronic leg ulceration and an ankle: brachial pressure index of 0.85 or greater were studied. Assessment of venous competence in both the deep and superficial systems of the affected and unaffected legs was performed using colour venous duplex imaging. Reflux was defined as reverse flow for greater than 1 s after manual calf compression. One hundred consecutive patients were assessed over 15 months. Of 111 ulcerated legs, 96 had active ulceration, while 15 had been ulcerated within the previous 6 months. Fifty-seven (51 per cent) of the 111 ulcerated legs had superficial incompetence alone (88 per cent long saphenous system or its perforators, 12 per cent short saphenous system). Six legs (5 per cent) had isolated deep venous incompetence. Forty-two legs had mixed superficial and deep venous reflux; 22 of these had undergone previous venous surgery. Colour venous duplex assessment demonstrated superficial venous disease in approximately half of limbs with chronic leg ulceration. Venous dysfunction in these patients is potentially curable by surgery.     

Ultrasound surveillance for asymptomatic deep venous thrombosis after total joint replacement

Prospective data on 202 consecutive patients who had a total of 123 total hip and ninety-four total knee arthroplasties were collected from two university medical centers. The findings of routine surveillance for deep venous thrombosis performed with ascending contrast venography were compared with those of surveillance with duplex ultrasonography complemented with color-flow Doppler imaging. All of the studies were performed between the third and seventh postoperative days. Of the 202 patients (342 extremities) who were examined, fifty-five (27 per cent) were found to have deep venous thrombosis; fifty-two (95 per cent) of the thrombi were in the calf and three (5 per cent) were in the proximal veins. All of the thrombi were clinically asymptomatic and all were nonocclusive, allowing passage of contrast medium around an intraluminal filling defect. Duplex ultrasonography with color-flow Doppler imaging correctly identified two of the three proximal thrombi and five of the fifty-two thrombi in the calf (sensitivity, 10 per cent). The sensitivity for the detection of thrombi in the calf was zero of sixteen at one of the institutions involved in the study and 14 per cent (five of thirty-six) at the other. There were two false-positive findings on ultrasonographic examination; one involved a proximal thrombus and one, a distal thrombus. We believe that the interinstitutional variability and insensitivity of duplex ultrasonography with color-flow Doppler imaging for the detection of asymptomatic deep venous thrombi in the calf after total joint replacement make it unreliable as a routine surveillance tool after total hip or knee arthroplasty.     

Evaluation of a new rapid D-dimer assay for clinically suspected deep venous thrombosis (Liatest D-dimer)

In previous studies, enzyme-linked immunosorbent assays (ELISA) for plasma D-dimer analysis have demonstrated high sensitivity, suggesting their potential usefulness in excluding deep venous thrombosis (DVT). We evaluated the usefulness of a new D-dimer test (Liatest D-dimer) for suspected DVT in a prospective study of patients admitted to the hospital because of recent (not exceeding 1 week before admission) clinical signs. Contrast venography or compression ultrasonography or both were performed within 24 hours of admission. A new quantitative determination of D-dimer concentration using a suspension of microlatex particles coated with specific antibodies was tested. A standard plasma D-dimer ELISA measurement was also performed. Of 464 patients, 276 had a proven DVT (distal, 74; proximal, 202). For a cutoff level of 400 ng/mL, sensitivity of the Liatest method in the diagnosis of overall DVT was 94.6% (95% confidence interval, 92.0%-97.0%), and the specificity was 35% (95% confidence interval, 28%-42%). The sensitivity and negative predictive value were 98.5% and 95.6%, respectively, in the diagnosis of proximal DVT, but only 83.8% and 84.6%, respectively, in the diagnosis of distal DVT. This new rapid Liatest D-dimer assay seems to be highly sensitive and could replace the ELISA method in excluding patients with proximal DVT. Both methods provide lower sensitivity for distal DVT.     

Bounds for generalized Dreitlein-Smoes models

The effect of elastic compression on venous flow in the legs provided by carefully fitted stockings has been measured by a venographic technic. The stocking used provides a gradually decreasing compression from ankle to groin. Clearance of stagnant blood from behind venous valves is clearly improved and the differences observed are statistically highly significant. These data suggest that the routine use of carefully fitted compression stockings will result in a decreased incidence of deep vein thrombosis (DVT) and provide a singularly safe, convenient, and noninvasive method of prophylaxis. Evidence presented suggests that at least two investigators have failed to show a decreased incidence of DVT in limbs subjected to elastic compression because the method of compression was inadequate .     

Graduated compression stockings in the prevention of deep vein thrombosis in patients with acute myocardial infarction

Venous volume (venous capacity) of the calf is low in patients with acute myocardial infarction, who also have a high risk of deep vein thrombosis (DVT). The effect of graduated compression stockings on the venous volume and on the incidence of DVT was therefore studied in 80 patients aged 70 years and above with acute myocardial infarction. Graduated compression stockings were randomly fitted to one leg, the other serving as a control, after which the venous volume was measured by strain gauge plethysmography. The incidence of DVT was measured by the 125I fibrinogen uptake test. Venous volume was significantly higher in legs treated with graduated compression stockings compared to control legs. DVT developed in eight control legs but not in any leg treated with graduated compression stockings (P = 0.003). DVT was also significantly more frequent in women compared to men and the majority of DVT developed in legs with very low venous volume values.     

Diagnostic value of compression ultrasonography and fibrinogen-related parameters for the detection of postoperative deep vein thrombosis following elective hip replacement: a pilot study

To determine their ability to diagnose postoperative deep vein thrombosis (DVT) D-dimer - by three methods -, fibrinogen degradation products (FgDP) and fibrinogen levels were measured in 68 consecutive patients before elective surgery for hip replacement and on postoperative day 1, 3, 6, and 10. All patients received prophylaxis and underwent compression real-time B-mode ultrasonography (C-US) on postoperative day 5 and 9, and bilateral ascending venography on day 10. Twenty-two out of 68 patients developed asymptomatic postoperative DVT, which was limited to the calf veins in 14 and involved the proximal veins in 8 patients. C-US was negative in all patients on day 5. On day 9, C-US sensitivity and specificity for proximal DVT were 63% (95% confidence interval: 26%-90% and 98% (89%-100%) respectively. Postoperative changes in the laboratory parameters evaluated were not different in patients with or without DVT until day 10. On day 10, mean D-dimer, FgDP and fibrinogen levels were significantly higher in patients with DVT than in those without DVT (p values between 0.006 and 0.032), but only D-dimer was higher with DVT involving two or more venous segments than with thrombosis involving one venous segment only (p < 0.05). Stepwise logistic regression analysis identified D-dimer and fibrinogen on day 10 as predictors of postoperative DVT. In a receiver operator curve and after weighing for the coefficients generated by logistic regression analysis, the combination of a latex photometric immuno-assay and of PT-derived fibrinogen yielded-at a cut-off value of 7.0 a sensitivity of 100% (73%-100%) and a specificity of 58% (39%-75%) for DVT, with a negative predictive value of 100% (78%-100%), a positive predictive value of 52% (32%-71%) and an overall accuracy of 71% (55%-83%). These results suggest that two simple, fast and reproducible tests may permit the identification of patients at low risk of having postoperative DVT and that a combination of sensitive laboratory assays and of the highly specific C-US may select patients requiring anticoagulant treatment. Efficacy and cost-effectiveness of this approach should be evaluated in large clinical management studies.     

Venous thrombosis causing arterial embolization to the same limb through a patent foramen ovale

We describe a patient who presented with acute ischemia affecting the left lower limb. Because a transthoracic echocardiogram was abnormal, a transesophageal study was arranged. This demonstrated an atrial septal aneurysm and right-to-left shunting of contrast, raising the possibility of paradoxical embolism. The diagnosis was confirmed by contrast venography, which showed extensive thrombosis in the deep veins of the left thigh, and a ventilation-perfusion scan which was consistent with multiple pulmonary emboli. Among the lessons from this case was the finding that in patients with arterial embolism the likely origin of the embolus should be considered and, in the absence of common risk factors (atrial fibrillation, rheumatic heart disease, left ventricular dilatation, widespread atheroma), occult venous thrombosis and a right-to-left shunt should be sought. In this select group of patients, transesophageal echocardiography is significantly more sensitive than transthoracic study and should be the investigation of choice. Second, in the patient described in this report the clinical signs of deep venous thrombosis (DVT) were masked by the more prominent features of acute arterial ischemia. Without the incidental echocardiographic abnormality, it is likely that the important diagnoses of DVT, pulmonary embolism, and paradoxical embolism would not have been made.     

In vivo effects of activated H-ras oncogene expressed in the liver and in urogenital tissues

PURPOSE: The clinical significance of isolated calf vein thrombosis (CVT), particularly with respect to development of the postthrombotic syndrome, remains controversial. The purpose of this study was to define the early natural history of CVT in relation to persistent lower extremity symptoms, propagation, recanalization, and the development of valvular incompetence. METHODS: Over a 116-month period, 499 patients with acute deep venous thrombosis (DVT) were referred to our research laboratory, of whom 58 (12%) had thrombosis confined to the calf veins of at least one extremity. The lower extremities of 268 patients (29 with isolated CVT) were followed-up clinically and with duplex ultrasonography at intervals of 1 day, 7 days, 1 month, every 3 months for the first year, and yearly thereafter. RESULTS: Seventy percent of extremities with CVT were symptomatic at presentation. Although the prevalence of clinical signs and symptoms decreased to 29% by 1 month, 23% of patients had persistent pain, edema, or both at 12 months. In contrast, 9% of uninvolved extremities contralateral to a CVT and 54% of extremities with proximal DVT remained symptomatic at 1 year (p = 0.004). Recanalization proceeded rapidly such that the mean thrombus load was reduced by 50% at 1 month and to zero at 1 year. The prevalence of valvular incompetence progressively increased such that reflux was present in 24% of extremities at 1 year. Although its investigation was not a primary goal of this study, pulmonary embolism was diagnosed at presentation and during follow-up in 11% and 3% of patients, respectively. CONCLUSIONS: The natural history of CVT is complicated by persistent symptoms and the development of valvular incompetence in approximately one-quarter of patients. This potential for persistent lower extremity symptoms should be considered in evaluating the clinical relevance of isolated calf vein DVT.     

Diagnosis of deep venous thrombosis and pulmonary embolism

Diagnostic evaluation in the patient with suspected deep vein thrombosis (DVT) and pulmonary embolism (PE) includes a clear correlation between clinical probability, test selection and test interpretation. Real-time B-mode ultrasound with color Doppler remains the imaging technique of choice in suspected DVT. The ventilation/perfusion (V/Q) lung scan is the preferred diagnostic modality in suspected PE. The D-dimer assay may be useful in excluding PA. New diagnostic techniques, including spiral computerized tomography may further modify the diagnostic algorithm.