Venous duplex imaging: should it replace hemodynamic tests for deep venous thrombosis?

Deep Vein Thrombosis in Intravenous Drug Users: An Invisible Global Health Burden

The prevalence of intravenous drug use has increased in the past decade and it represents an important risk factor for deep vein thrombosis. Intravenous drug use is a global problem, with the main culprit being heroin. Peer pressure and poverty in high-risk groups such as sex workers, females, and young adults raise the risk of intravenous drug use, which expresses itself in the form of venous thromboembolism eventually. Deep vein thrombosis typically manifests itself eight years after the initial intravenous drug administration, rendering it a silent killer. Aiming to review and summarize existing articles in this context, we performed an exhaustive literature search online on PubMed and Google Scholar indexes using the keywords "Deep Venous Thrombosis (DVT)" and "Intravenous Drug Users (IVDU)." English articles that addressed epidemiology, pathogenesis, clinical manifestations, diagnosis, differential diagnosis, management, and outcomes of DVT, including those in IVDU, were selected and analyzed. The pathogenesis of DVT development in IVDU is mainly attributed to the interplay of trauma to the vessel by repeated injection and the injected drug itself. The right-sided femoral vein is the most common vein affected. Prevalent clinical presentations include local pain, swelling, and redness with typical systemic symptoms including fever, cough, dyspnea, and chest pain on top of addiction features. There appeared to be a delay in reporting symptoms, which was most likely due to the social stigma attached to IVDU. There are over 50 conditions that present with swollen and painful limbs comparable to DVT in IVDU, making precise diagnosis critical for timely treatment. Venous ultrasound is the method of choice for diagnosing DVT. Extended anticoagulant therapy with low-molecular-weight heparin combined with warfarin is the recommended treatment. Intravenous drug abusers having DVT are affected by multiple complications and poorer outcomes such as slower recovery, recurrent venous thromboembolism (VTE), and a longer hospital stay, which put them at higher risk of morbidity, mortality, reduced productivity, and economic burden.

Prospective study of deep vein thrombosis in patients with spinal cord injury not receiving anticoagulant therapy

STUDY DESIGN

Prospective cross-sectional study.

OBJECTIVES

To investigate the timing of deep vein thrombosis (DVT) onset secondary to spinal cord injury without anticoagulant therapies.

SETTING

Spinal Cord Injury Center in Hokkaido, Japan.

METHODS

Between November 2012 and June 2013, patients with spinal cord injury who were admitted to our hospital within 1 day after the injury and treated surgically within 24 h underwent a neurological examination, leg vein ultrasonography and D-dimer test 1, 3, 7, 14 and 28 days after surgery. All patients received treatment with intermittent pneumatic compression and elastic stockings, but without any anticoagulant.

RESULTS

DVT developed in 12 patients (11 men and 1 women), with a mean age of 62.2 years (range, 41-80 years; mean age of total sample, 63.2 years (range, 25-78 years)), all distal to the popliteal vein. DVT occurred more often with a more severe paralysis (66.3%, AIS A and B). The median (± standard error) length of time from the operation to DVT detection was 7.5±2.2 days. The mean D-dimer level upon DVT detection was 14.6±11.8 μg ml(-1), with no significant differences between those who developed DVT and those who did not at any of the time points.

CONCLUSION

These results suggest that DVT can develop at the very-acute stage of spinal cord injury and the incidence increases with a more severe paralysis. DVT detection was more reliable with ultrasonography, which should be used with DVT-preventive measures, beginning immediately after the injury, for the management of patients with spinal cord injury.

Meta-analysis of plethysmography and rheography in the diagnosis of deep vein thrombosis

BACKGROUND

Plethysmography and rheography techniques have been widely studied as diagnostic tests for deep vein thrombosis (DVT). This study aimed to systematically review the accuracy of these tests for diagnosing clinically suspected DVT.

METHODS

The following databases were searched: Medline, EMBASE, CINAHL, Web of Science, Cochrane Database of Systematic Reviews, Cochrane Controlled Trials Register, Database of Reviews of Effectiveness, the ACP Journal Club (1966 to 2004), and citation lists of retrieved articles. Studies that compared plethysmography or rheography to a reference standard of ultrasound or contrast venography were selected. Standardised data were extracted and study quality determined against validated criteria. Data were analysed by random effects meta-analysis and meta-regression.

RESULTS

The meta-analysis included 78 studies, reporting 82 patient cohorts. Sensitivity and specificity (95% CI) were: 75% (73% to 77%) and 90% (89% to 91%) for impedance plethysmography, 83% (81% to 85%) and 81% (79% to 82%) for strain-gauge plethysmography, 85% (79% to 90%) and 91% (81% to 95%) for air plethysmography, 91% (87% to 94%) and 71% (66% to 75%) for light-reflex rheography, and 86% (83% to 89%) and 93% (91% to 95%) for phleborheography. Meta-regression was limited by poor reporting of studies. There was some evidence that diagnostic performance depended on the proportion of males in the cohort and reporting of study setting.

CONCLUSIONS

Although plethysmography and rheography techniques add diagnostic value, they have inadequate diagnostic performance to act as a stand-alone test in DVT diagnosis. Evaluation of their role in combination with other tests, or standardised clinical assessment, is required.

Prospective Evaluation of a Screening Protocol to Exclude Deep Vein Thrombosis on the Basis of a Combination of Quantitative D-Dimer Testing and Pretest Clinical Probability Score

BACKGROUND

Clinical signs and symptoms such as swelling, pain, and redness are unreliable markers of deep vein thrombosis (DVT). Because of this venous duplex scanning (VDS) has been heavily used in DVT detection. The purpose of this study was to determine if a combination of D-dimer testing and pretest clinical score could reduce the use of VDS in symptomatic patients with suspected DVT.

STUDY DESIGN

One hundred seventy-four consecutive patients with suspected DVT were prospectively evaluated using pretest clinical probability (PCP) score and D-dimer testing before VDS. After calculating clinical probability scores developed by Wells and associates, patients were divided into low risk (<or= 0 points), moderate risk (1 to 2 points), and high risk (>or=3 points) PCP.

RESULTS

One hundred fifty-eight patients were enrolled. The prevalence of DVT in this study was 37%. Thirty-eight patients (24%) were classified as low risk, 64 (41%) as moderate risk, and 56 (35%) as high risk PCP. DVT was identified in only one patient (2.6%) with low risk PCP. In contrast, DVT was found in 22 (34%) with moderate risk, and 35 (63%) with high risk PCP. In the high and moderate risk PCP groups, positive scan patients had a markedly higher value of D-dimer assay than negative scan patients (p=0.0001 and p=0.0057, respectively). In the low risk PCP patients, D-dimer testing provided 100% sensitivity, 46% specificity, 4.8% positive predictive value, and 100% negative predictive value in the diagnosis of DVT. Similarly, in the moderate risk PCP, the D-dimer testing showed 100% sensitivity, 45% specificity, 49% positive predictive value, and 100% negative predictive value. In the high risk group, D-dimer testing achieved 100% sensitivity, 57% specificity, 80% positive predictive value, and 100% negative predictive value in the diagnosis of DVT. These results suggested that 36 of 158 patients who had a non-high PCP (low and moderate PCP) and a normal D-dimer concentration were considered to have no additional investigation, so VDS could have been reduced by 23% (36/158).

CONCLUSIONS

A combination of D-dimer testing and clinical probability score may be effective in avoiding unnecessary VDS in suspected symptomatic DVT in the low and moderate PCP patients. The need for VDS could be reduced by 23% despite a relatively high prevalence of DVT.

Systematic review and meta-analysis of the diagnostic accuracy of ultrasonography for deep vein thrombosis

BACKGROUND

Ultrasound (US) has largely replaced contrast venography as the definitive diagnostic test for deep vein thrombosis (DVT). We aimed to derive a definitive estimate of the diagnostic accuracy of US for clinically suspected DVT and identify study-level factors that might predict accuracy.

METHODS

We undertook a systematic review, meta-analysis and meta-regression of diagnostic cohort studies that compared US to contrast venography in patients with suspected DVT. We searched Medline, EMBASE, CINAHL, Web of Science, Cochrane Database of Systematic Reviews, Cochrane Controlled Trials Register, Database of Reviews of Effectiveness, the ACP Journal Club, and citation lists (1966 to April 2004). Random effects meta-analysis was used to derive pooled estimates of sensitivity and specificity. Random effects meta-regression was used to identify study-level covariates that predicted diagnostic performance.

RESULTS

We identified 100 cohorts comparing US to venography in patients with suspected DVT. Overall sensitivity for proximal DVT (95% confidence interval) was 94.2% (93.2 to 95.0), for distal DVT was 63.5% (59.8 to 67.0), and specificity was 93.8% (93.1 to 94.4). Duplex US had pooled sensitivity of 96.5% (95.1 to 97.6) for proximal DVT, 71.2% (64.6 to 77.2) for distal DVT and specificity of 94.0% (92.8 to 95.1). Triplex US had pooled sensitivity of 96.4% (94.4 to 97.1%) for proximal DVT, 75.2% (67.7 to 81.6) for distal DVT and specificity of 94.3% (92.5 to 95.8). Compression US alone had pooled sensitivity of 93.8 % (92.0 to 95.3%) for proximal DVT, 56.8% (49.0 to 66.4) for distal DVT and specificity of 97.8% (97.0 to 98.4). Sensitivity was higher in more recently published studies and in cohorts with higher prevalence of DVT and more proximal DVT, and was lower in cohorts that reported interpretation by a radiologist. Specificity was higher in cohorts that excluded patients with previous DVT. No studies were identified that compared repeat US to venography in all patients. Repeat US appears to have a positive yield of 1.3%, with 89% of these being confirmed by venography.

CONCLUSION

Combined colour-doppler US techniques have optimal sensitivity, while compression US has optimal specificity for DVT. However, all estimates are subject to substantial unexplained heterogeneity. The role of repeat scanning is very uncertain and based upon limited data.

Patterns of Venous Insufficiency after an Acute Deep Vein Thrombosis

BACKGROUND

The purpose of this study was to investigate patterns of venous insufficiency during a 12-month period after an acute deep vein thrombosis.

STUDY DESIGN

Seventy limbs in 67 patients with an acute deep vein thrombosis (DVT) involving 147 anatomic segments were evaluated with duplex scanning at 1 month, 3 months, 6 months, and 1 year. Venous segments were examined whether they were occluded, partially recanalized, or totally recanalized, and the development of venous reflux was evaluated.

RESULTS

The segments investigated were the common femoral vein (38 segments), femoral vein (33 segments), popliteal vein (36 segments), and calf veins (40 segments). There were 35 limbs with isolated DVT and the remaining 35 had multisegment DVT. At 1 year, thrombi had fully resolved in 76% of the segments, 20% remained partially recanalized, and 5% were occluded. The venous occlusion was most predominant in the femoral vein (21%) at 1 year. On the contrary, rapid recanalization was obtained in calf veins than in proximal veins at each examination (p < 0.01). Deep vein insufficiency was detected as early as 1 month after development of DVT, and the reflux was most predominant in popliteal veins (56%), followed by femoral veins (18%). No reflux was found in calf veins. Multisegment DVTs had a significantly higher incidence of deep vein insufficiency than single segment DVTs at 1 year. Development of superficial venous insufficiency was found in 5 limbs (7%) and perforating vein insufficiency in 5 (7%).

CONCLUSIONS

Lower extremity venous segments showed different proportions of occlusion, partial recanalization, and total recanalization. Calf veins showed more rapid recanalization than proximal veins. Venous reflux was noted as early as 1 month. The limbs involving multisegment DVTs on initial examination had a higher incidence of deep vein insufficiency and could require much longer followup studies.

A systematic review of the accuracy of ultrasound in the diagnosis of deep venous thrombosis in asymptomatic patients

Evaluation of the accuracy of ultrasound has yielded heterogeneous results. Our objective was to summarize the evidence on the accuracy of ultrasound compared to venography in asymptomatic patients, taking into account the variation due to threshold differences. Searches of journal table of contents, computer databases (Medline, Embase, Biomed, Cochrane) and conference proceedings were performed. A study was eligible if it prospectively compared ultrasound to venography for the diagnosis of DVT in asymptomatic patients. Data of studies selected for inclusion were extracted independently by two authors. High quality studies with consecutive patient enrollment, blind evaluation of the two techniques, and absence of verification bias are summarized as Level 1, while those not fulfilling one or more of these criteria are considered Level 2. Original study authors were contacted to confirm accuracy and to provide missing data. A pooled estimate of the accuracy of ultrasound was obtained according to the method of Moses and coworkers. This method gives a summary diagnostic odds ratio (DOR). The DOR is a single indicator of test performance. It varies between 0 and infinity and exceeds 1, only when ultrasound is more often positive in patients with DVT relative to those without DVT. Higher DOR indicates better discriminatory test performance. Thirty one studies were rated as potentially unbiased and graded as Level 1. The mean prevalence of DVT as determined by venography was 22%. In Level 1 studies, the odds of positive ultrasound in proximal veins was 379 times higher (95% confidence limits 65, 2,200) and in distal veins 32 times higher (7.5, 135) among patients with DVT than those without. Our results suggest that, particularly for proximal veins, ultrasound is accurate for the diagnosis of DVT in asymptomatic postoperative orthopedic patients. More research is needed in other clinical settings.

Safety and Outcomes of Short-Term Multiple Femoral Venous Sheath Placement in Cardiac Electrophysiological Study and Radiofrequency Catheter Ablation

Multiple intracardiac catheters are often necessary for electrophysiological study (EPS) and radiofrequency (RF) ablation therapy. Therefore, multiple venous sheath placement in one femoral vein is always required for multiple intracardiac catheter insertion. The vascular complications incurred by placement of multiple sheaths have not been fully studied. We utilized duplex ultrasonography to assess the femoral veins before and after the procedure. This study consisted of 52 patients (68 femoral veins) who underwent EPS and RF ablation therapy. Up to three sheaths were inserted into a single femoral vein. Nonocclusive deep vein thrombosis (DVT) occurred in 12/68 veins (17.6%) of 11 patients on the day following the procedure. Thrombosis regressed spontaneously in 11 veins and persisted in 1 vein at 1-week follow-up. The venous diameter significantly decreased the day after the procedure (8.7 +/- 1.2 mm vs 5.3 +/- 1.5 mm, P < 0.001), but recovered by the 1-week follow-up (7.9 +/- 1.7 mm, P = 0.07) in the 12 veins. Short-term placement of multiple venous sheaths in a single femoral vein appears to be safe. Nonetheless, nonocclusive DVT does occur in a significant number of patients. Although thrombosis regressed and the outcome appeared to be benign in most patients, close follow-up to avoid potential vascular complications is necessary.

Comprehensive deep venous thrombosis prevention strategy after total-knee arthroplasty

OBJECTIVE

Venous thromboembolism after total-knee arthroplasty represents a common early postoperative complication resulting in significant morbidity. Despite this, the optimal prophylactic regimen is controversial. The prevalence of venous thromboembolism has been cited as high as 35% in patients receiving pharmacologic prevention alone. We investigated the efficacy of a comprehensive prevention protocol encompassing the use of epidural anesthesia, aspirin, venous foot compression pumps, and early mobilization in a series of consecutive total-knee arthroplasties.

DESIGN

A series of 100 consecutive total-knee arthroplasty patients were enrolled into the prospective trial. All patients were allowed full weight bearing on the first postoperative day and ambulation as tolerated. Venous foot compression pumps and aspirin were used immediately after surgery in the totality of subjects. Seventy-five percent of the patients were transferred to an acute rehabilitation service during the first postoperative week. The presence of deep-vein thrombosis was subsequently determined with the routine use of venous duplex scans.

RESULTS

Three patients (3%) demonstrated evidence of distal deep-vein thrombosis. No patient had symptomatic pulmonary embolism.

CONCLUSION

The combination of epidural anesthesia, aspirin, immediate postoperative venous foot compression pumps, and early ambulation together seem to be a more effective approach to prevent the occurrence of thromboembolic events after knee replacements than pharmacologic prevention alone.

Duplex ultrasonography after total hip or knee arthroplasty

We prospectively studied all patients admitted for total hip (THR) or knee (TKR) arthroplasty from July 2000 to February 2001. No pharmacological anticoagulation was given. All patients received a standardized postoperative rehabilitation regimen. Forty-six patients with known risk factors for deep vein thrombosis (DVT) were excluded. Eighty patients were studied (22 THR, 58 TKR; 55 women, 25 men). Mean age was 68 (30-90) years. Duplex ultrasonography on both lower limbs was performed on days 5-7 postoperatively. Location and extent of any thrombus were documented. In patients with distal DVT, a follow-up scan was done on days 10-14. If proximal propagation was observed, patients received full anticoagulation. If no propagation was detected, the distal thrombus was considered stable and clinical observation was continued. In the THR group, 1/22 and in the TKR group 9/58 were found to have distal DVT. All were asymptomatic. On follow-up scanning, none showed proximal propagation. All patients were followed up for at least 18 months, and none showed postthrombotic symptoms. Isolated distal DVT in "low-risk" Chinese patients after THR or TKR is not uncommon. Clinically they are usually "silent." If routine perioperative pharmacologic antithrombotic prophylaxis is not practiced, monitoring with duplex ultrasonography may need to be considered.

Appropriate indications for venous duplex ultrasonographic examinations

BACKGROUND

Because of the rapid growth in requests for lower extremity venous duplex ultrasonographic examinations, we have evaluated test results to determine the appropriate indications for testing and whether there is overuse of this technique.

METHODS

We reviewed the records of all patients who had duplex ultrasonogram during an 18-month period to rule out deep vein thrombosis (DVT). Test outcome was evaluated with data on the age, gender, outpatient or inpatient status, duration of symptoms, physical findings, and risk factors of the patients.

RESULTS

We reviewed 3474 examinations; 1265 outpatients and 1231 inpatients were evaluated to rule out DVT, and 978 patients were evaluated to rule out a source of pulmonary embolism. More outpatients were female, and they tended to be younger; outpatients also had more acute femoropopliteal DVT. The presence of sudden onset of unilateral swelling was a strong predictor of acute DVT in all three groups: 52% of such patients were found to have DVT. Mild unilateral symptoms with a coexistent risk factor was associated with a 10% to 20% prevalence of acute DVT. Chronic unilateral swelling was associated with acute DVT only with a coexistent risk factor and only in 1% of such patients. Bilateral swelling was only associated with acute DVT in the inpatient population, with 17% of studies having positive results. If calf tenderness was the only symptom with no associated risk factors, seven (1.6%) of 415 patients had acute DVT and six of these were tibioperoneal. No patients with cellulitis or isolated joint pain had acute DVT. With clinically suspected pulmonary embolism in patients without associated symptoms or risk factors, 7 (1.5%) of 447 studies showed tibioperoneal disease with no acute femoropopliteal disease.

CONCLUSIONS

The physical examination and clinical history of the patient remain important indicators of the presence (or absence) of lower extremity DVT and can guide the appropriate use of duplex ultrasonography for the diagnosis.

A prospective study comparing duplex scan and venography for diagnosis of lower-extremity deep vein thrombosis

This study was designed to compare duplex scanning with contrast venography for the diagnosis of acute deep vein thrombosis of the lower extremity, both at the femoropopliteal (above-knee) and tibioperoneal (below-knee) levels. A total of 216 patients with 220 limbs suspected of acute deep vein thrombosis underwent duplex scanning followed within 24 h by ascending venography. The two studies were interpreted independently by two physicians who were blinded to the results of the corresponding alternative study. Venography was positive for deep vein thrombosis in 44.5% of cases (98/220). Duplex scanning was inadequate at the above-knee level in two cases (0.9%) and at the below-knee level in 17 cases (7.7%). Sensitivity and specificity of duplex scanning at above-knee level were 98.7% and 100% respectively while corresponding values were 85.2% and 99.2% at below-knee level. By excluding technically inadequate duplex studies, the sensitivity at below-knee level was clearly improved (93.8%). It is concluded that with meticulous technique, duplex scanning is highly accurate in diagnosing acute deep vein thrombosis of symptomatic lower extremities, avoiding contrast venography in over 90% of the cases, even at the tibioperoneal level.

The diagnosis of deep vein thrombosis in the multiply injured patient with pelvic ring or acetabular fractures

Thirty-one patients with unstable displaced pelvic or acetabular fractures were admitted and underwent an open reduction and internal fixation of their fracture. All patients were studied prospectively for the incidence of proximal deep vein thrombosis (DVT) utilizing venous duplex ultrasound. Duplex scans were repeated at 1 week postoperatively in all patients. Additional scans were performed when clinically indicated. A total of 61 scans were completed. DVT developed in three patients (approximately 10%). Two of the three positive scans were noted only on postoperative examination. The third scan was positive on the preoperative phase. Duplex ultrasound was easily applied and well tolerated by the multiply injured patient.

Limitations of compression ultrasound for the detection of symptomless postoperative deep vein thrombosis

Compression ultrasonography is regarded as the non-invasive gold-standard to detect deep vein thrombosis (DVT) in patients presenting with symptoms. However, its use as a screening method in symptom-free postoperative patients at high risk of developing DVT remains controversial. In 100 consecutive patients who had undergone craniotomy, we compared the results of bilateral compression ultrasonic measurements of the results of bilateral compression ultrasonic measurements of the entire legs with the outcomes of contrast venography. Proximal DVT was detected in 13 patients, 5 of whom also had an abnormal ultrasonic result (sensitivity 38%, 95% CI 8-69%). Only 5 of the 9 patients with an abnormal ultrasound result for the proximal veins had proximal DVT (positive predictive value, 56%, 18-94%). Calf sonograms were evaluable in 71 of the 91 patients with bilaterally normal ultrasound results for the proximal veins. Of the 16 patients with calf DVT, ultrasound was abnormal in 8 (sensitivity 50%, 25-75%). Overall, ultrasound detected 13 of the 26 patients with proximal or isolated calf DVT (sensitivity 50%, 29-71%). The positive predictive value for the whole leg examination was 41% (24-60%). Most thrombi missed by ultrasound were non-occlusive and smaller than 5 cm. We conclude that compression ultrasound is not useful for screening for DVT in symptom-free postoperative high-risk patients.