The diagnosis of lower extremity deep venous thrombosis

Clinical significance of recurrent venous thromboembolism

Recurrent venous thromboembolism is a significant problem leading to increased morbidity and mortality. It has a high impact on patients' quality of life and imposes a great financial burden on society. Cumulative recurrence has been reported as 40% at 10 years, while the chance of developing postthrombotic signs and symptoms in the lower extremities almost quadruples when ipsilateral. There is also a higher chance of developing pulmonary hypertension. Important factors for recurrence are unprovoked episodes of deep vein thrombosis, malignancy and older age. The evidence for other factors is controversial. Accurate diagnosis and treatment tailored to the patients' history, thrombotic events and risk factors are necessary to optimize management and prevent recurrence.

Impact and clinical significance of recurrent venous thromboembolism

Background

The purpose of this review was to analyse current knowledge and controversies associated with the diagnosis, treatment and prevention of recurrent venous thromboembolism (VTE).

Methods

MEDLINE and manual searches were performed to select prospective papers on the diagnosis, treatment and prevention of recurrent VTE for their relevance and quality.

Results

The cumulative incidence of recurrent VTE increases from 11 per cent at 1 year to 40 per cent at 10 years. The incidence of recurrence is higher in unprovoked thrombosis compared with provoked VTE. Patients with unprovoked deep vein thrombosis also have a greater number of multiple recurrences. Ultrasonography or D-dimer monitoring may have an impact on the duration of anticoagulation but further refinements are needed. The incidence of skin damage is higher in ipsilateral recurrence compared with contralateral or no recurrence. Legs with ipsilateral recurrence more often have both reflux and obstruction.

Conclusion

The role and weight of the predictive factors for recurrent VTE and its sequelae, and the type and optimal duration of anticoagulation have not been studied adequately. Fatality associated with pulmonary embolism and rates of recurrent VTE remain unacceptably high.

64-Multidetector-row spiral CT in pulmonary embolism with emphasis on incidental findings

AIM

In this retrospective study, we assess the current role and future potential of computed tomography (CT) in the diagnostic algorithm of acute pulmonary embolism (PE).

MATERIALS AND METHODS

Two hundred patients underwent 64-multidetector-row spiral CT of the chest, pelvis, and thigh for suspected PE. CT scans were reviewed, and the degree of contrast enhancement and the presence of PE and/or (deep) venous thrombosis were recorded. In the case of PE, the level of thrombus was noted as central, main, or lobar. If the scan yielded a positive result for thrombosis, intravenous localization was also determined. Patient age, length of admission, clinical course, clinical indication, and incidental findings were registered as well.

RESULTS

PE was detected in 60 of the 200 patients with a high clinical probability of having PE (30%). Thirty-four patients had a positive CT scan result for venous thrombosis (17%). Twenty-four of the 60 patients had proximal deep venous thrombosis (40%), and 2 patients had arm venous thrombosis (3%). Thirty-four of the 60 patients had PE without venous thrombosis (57%). Eight of the 200 patients had deep venous thrombosis without suspicion of PE (4%). The distribution of the proximal thrombi showed 15 in a central artery (25%), 13 in a main pulmonary artery (22%), and 32 in a lobar segmental artery (53%). There was diffuse allocation of the thrombus in all lobes. Furthermore, CT scan noted a total of 120 incidental findings.

CONCLUSION

Our study indicates the potential clinical use of a diagnostic strategy for ruling out PE based on D-dimer testing and multidetector-row CT. A larger outcome study is needed before this approach can be adopted.

Venous thromboembolism in trauma patients

Serial venous duplex scans (VDS) were done in 507 trauma patients with at least one risk factor (RF) for venous thromboembolism (VTE) during a 2-year study period. Deep vein thrombosis (DVT) was detected in 31 (6.1%) patients. This incidence was 3.1 per cent in low (1-2 RFs), 3.4 per cent in moderate (3-5 RFs), and 7.7 per cent in high (> or =6 RFs) VTE scores (P = 0.172). Incidence was statistically different (3% vs. 7.2%, P = 0.048) on reanalyzing patients in two risk categories, low-risk (1-4 RFs) and high-risk (> or =5 RFs). Only 4 of 16 RFs had statistically higher incidence of DVT in patients with or without RFs: previous VTE (27.3% vs. 5.6%, odds ratio (OR) 6.628, P = 0.024), spinal cord injury (22.6% vs. 5%, OR 5.493, P = 0.001), pelvic fractures (11.4% vs. 5.1%, OR 2.373, P = 0.042), and head injury with a greater than two Abbreviated Injury Score (10.5% vs. 4.2%, OR 2.639, P = 0.014). On reanalyzing patients with > or =5 RFs vs. <5RFs, obesity (14.3 vs. 6.1%, P = 0.007), malignancy (5.6% vs. 0.6%, P = 0.006), coagulopathy (10.8% vs. 1.8%, P = 0.000), and previous VTE (3.2% vs. 0%, P = 0.019) were significant on univariate analysis. Patients with DVT had 3.70 +/- 1.75 RFs and a 9.61 +/- 4.93 VTE score, whereas, patients without DVT had 2.66 +/- 1.50 RFs and a 6.83 +/- 3.91 VTE score (P = 0.000). DVTs had a direct positive relationship with higher VTE scores, length of stay, and number of VDS (>1 r, P < or = 0.001). Increasing age was a weak risk factor (0.03 r, P = 0.5). First two VDS diagnosed 77 per cent of DVTs. Patients with injury severity score of > or =15 and 25 had higher DVTs compared with the ones with lower injury severity score levels (P < or = 0.05). Pulmonary embolism was silent in 63 per cent and DVTs were asymptomatic in 68 per cent.

Helical CT for the Evaluation of Acute Pulmonary Embolism

OBJECTIVE

In this article, we review the current role of CT pulmonary angiography and indirect CT venography for the evaluation of pulmonary thromboembolic disease.

CONCLUSION

With advances in MDCT technology, evaluation of pulmonary thromboembolic disease can now be performed with combined CT pulmonary angiography and CT venography as a "one-stop-shopping" test. CT pulmonary angiography is cost-effective, is accurate, has high interobserver agreement, and has an added advantage of detecting other life-threatening diseases in the chest that mimic pulmonary embolism.

Combining clinical risk with D-dimer testing to rule out deep vein thrombosis

We sought to determine whether the combination of low-intermediate clinical risk of acute lower extremity deep vein thrombosis (DVT) and negative ELISA D-dimer assay can eliminate the need for duplex ultrasonography. Three hundred thirty-six patients prospectively underwent clinical risk stratification (low, intermediate, and high), D-dimer testing, and duplex ultrasonography. Thirteen of 145 intermediate-risk patients had acute DVT; 11 (85%) had a positive D-dimer. Two of 118 low-risk patients had acute DVT; both had a positive D-dimer. Intermediate-high risk stratification alone had sensitivity of 93.9% (95% CI: 80.3-98.3%) and a NPV of 98.3% (95% CI: 94.0-99.5%) for acute DVT. For all patients, a positive D-dimer alone had a sensitivity of 93.9% (95% CI: 80.3-98.3%) and a NPV of 98.6% (95% CI: 95.1-99.6%). The combination of D-dimer and intermediate-high risk classification had a sensitivity of 100% (95% CI: 89.4-100%) and a NPV of 100% (95% CI: 98.9-100%). In suspected acute lower extremity DVT, the combination of intermediate-high clinical risk and positive D-dimer has a high sensitivity and NPV, possibly eliminating the need for duplex ultrasound in this group of patients.

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.