Diagnostic management of venous thromboembolism

Appropriate Use of Venous Imaging and Analysis of the D-Dimer/Clinical Probability Testing Paradigm in the Diagnosis and Location of Deep Venous Thrombosis

BACKGROUND

The D-dimer (DD) level combined with the pretest Wells criteria probability (WCP) score can safely exclude deep venous thrombosis (DVT). The objective of this study was to examine the correlation between DD results alongside WCP score with findings on venous duplex ultrasound (VDU). The hypothesis is that VDU remains overutilized in low-risk patients with negative DD and that higher DD levels may correlate with thrombus burden and location.

METHODS

Patients who presented to a high-volume tertiary care center with lower limb swelling with or without associated pain were retrospectively examined through June and July for 4 consecutive years (2012 to 2015). After calculating WCP, patients were divided into low-, moderate-, and high-risk categories. Electronic DD results utilizing enzyme linked immunosorbent assay, WCP data, and VDU analysis data were merged and analyzed based on receiver operator characteristic curve to determine the DD cutoff point for each WCP. Abnormal DD with an average value ≥ 0.6 mg/L fibrinogen equivalent units (FEUs) was correlated to positive DVT to differentiate proximal DVT (above popliteal vein) from distal DVT (below popliteal vein).

RESULTS

Data of 1,909 patients were analyzed, and 239 (12.5%) patients were excluded secondary to serial repeat visits or follow-ups, surveillance screens, and if they had a previous history of DVT. The average age was 62.1 ± 16.3 years with more women (55.7%) and the majority presented with limb pain and edema (87%). DD studies were ordered and completed in 202 patients and correlated with all positive and negative DVT patients (100% sensitivity and negative predictive value, with specificity and positive predictive value of 14.9% and 15.9%, respectively). Twenty-six of 202 patients had DD that were in the normal range 0.1-0.59 mg/L (FEU), all of which were negative for DVT (100% sensitive). Fifty one of 202 patients had DD values of 0.6-1.2 mg/L FEU, of which only 3 DVTs were recorded, and all of them were distal DVTs. In addition, 685 patients with WCP <1 and negative DD were sent for VDU. Thus, 762 patients had an unnecessary immediate VDU (Wells ≤1 and -DD) study during their initial presentation. Potential charge savings for VDU for all patients are 762 × $1,557 = $1,186,434 and DD for all patients are 762 × $182 = $138,684, with total potential savings of $1,047,750 (USD 2016).

CONCLUSIONS

This study suggests that DD is still underutilized, and DD in conjunction with WCP could significantly reduce the number of unnecessary immediate VDUs. Higher value of DD (>1.2 mg/L FEU) may raise concern for proximal DVT. Concern on cost-effectiveness exists and raises the demand for a proposed algorithm to be followed.

In too deep: understanding, detecting and managing DVT

Venous thromboembolism (VTE), which includes deep vein thrombosis (DVT) and pulmonary embolism (PE), is a serious health and social care problem of the developed world, affecting 1 in 1000 adults every year, and with an annual financial overhead of approximately £640 million. The nature of DVT means that often the condition can go unrecognized until the thrombus becomes an embolus. The pathogenesis of DVT continues to be based on Virchow's triad, which attributes VTE to 'hypercoagulability', 'stasis' and 'intimal injury'. The diagnosis of DVT is often the result of a number of tests performed either sequentially or in combination before mechanical and/or chemical treatment is embarked on. Creating public awareness of DVT and PE is the best way to prevent this condition. Nurses are in an ideal position to discuss the importance of lifestyle changes and other related measures to prevent DVT.

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.

Screening for Deep Vein Thrombosis in Asymptomatic High-risk Patients: A Comparison between Digital Photoplethysmography and Venous Ultrasonography

Objective

To determine the role of digital photoplethysmography in screening asymptomatic patients who are susceptible for developing deep vein thrombosis.

Methods

Three hundred and thirty-seven limbs in 169 patients who were high risk for development of deep vein thrombosis were assessed by ultrasonography digital photoplethysmography and the results were compared.

Results

Thirteen limbs were found to have deep vein thrombosis as demonstrated by ultrasonography. All limbs with a venous refilling time greater than 12 seconds had a normal ultrasonography. Compared with ultrasonography and using refilling time less than 12 seconds as the cutoff point, digital photoplethysmography achieved a sensitivity, specificity, positive predictive value, and negative predictive value of 100%, 73.8%, 13.3%, and 100% respectively, for detecting deep vein thrombosis in asymptomatic high-risk patients.

Conclusion

Digital photoplethysmography is a simple, noninvasive, and highly sensitive test for screening of deep vein thrombosis.

Type and location of venous thromboembolism in patients with factor V Leiden or prothrombin G20210A and in those with no thrombophilia

BACKGROUND

Patients with factor (F) V Leiden or the prothrombin G20210A polymorphism are at increased risk of developing deep vein thrombosis (DVT). On the other hand, the risk of developing pulmonary embolism (PE) appears to be low in carriers of FV Leiden, perhaps because of a lower tendency to develop iliofemoral DVT than non-carriers. For prothrombin G20210A, data are scanty and controversial.

METHODS

The clinical manifestations (isolated DVT, DVT and PE, and isolated PE), the extension of DVT, and the presence of transient risk factors were retrospectively investigated in 115 patients with heterozygous FV Leiden, 87 with prothrombin G20210A and 200 with no thrombophilia marker.

RESULTS

Isolated symptomatic PE was less prevalent in patients with FV Leiden (6%) than in those with prothrombin G20210A (21%) and no thrombophilia (23%) (P > 0.0001). The rate of distal DVT was higher in patients with no thrombophilia (16% vs. 7% for FV Leiden and 6% for prothrombin G20210A) (P = 0.02). No difference in the incidence of PE from distal and proximal DVT, the extension of proximal DVT and the type of transient risk factors for venous thromboembolism (VTE) was found in the three groups. Patients with prothrombin G20210A had a younger age at their first VTE (24 years, P < 0.0001) and a higher rate of DVT accompanying PE (P = 0.04) than those with FV Leiden or no thrombophilia.

CONCLUSIONS

Carriers of prothrombin G20210A, unlike those of FV Leiden, have an increased risk of developing isolated PE. This difference was not explained by a different rate of distal DVT, extension of proximal DVT, or distribution of transient risk factors in the two groups. Patients with prothrombin G20210A have more severe clinical manifestations than those with FV Leiden or no thrombophilia.

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.

Traveler's thrombosis: a systematic review

BACKGROUND

Anecdotal evidence suggests a possible link between travel and venous thromboembolism (VTE). We systematically evaluated the evidence from observational studies.

METHODS

We searched studies evaluating the risk of venous thrombosis in relation to traveling from MEDLINE and EMBASE up tp March 2004, together with a hand search of reference lists from retrieved literature, and we contacted some of the experts. Observational studies estimating the risks of VTE and isolated calf vein thrombosis were eligible. Methodologic quality was assessed based on prior criteria, and meta-analysis was considered where applicable.

RESULTS

A total of 194 English-language publications were initially identified. Sixteen studies were included: 9 case-control, 2 prospective controlled, and 5 other observational studies. They differed drastically in study designs, selection of controls where applicable, mode and duration of travel, and subtypes of VTE under consideration. Ten studies concluded that travel, mostly through air and of prolonged duration, is a risk factor for venous thrombosis and/or pulmonary embolism, and the risk increases for passengers with preexisting venous thrombosis risk factors. Outcomes examined ranged from asymptomatic isolated calf muscle vein thrombosis to severe fatal pulmonary embolism.

CONCLUSIONS

Current literature is controversial over any association between travel and VTE, and although the quality and power of these studies have been variable, studies of higher quality have shown a strong and significant association between prolonged air travel and VTE. No conclusions could be drawn about other modes of transportation. Since VTE is a disease of multifactorial causation, those with preexisting VTE risk factors are most vulnerable.

Evaluation of the Simplify D-dimer assay as a screening test for the diagnosis of deep vein thrombosis in an emergency department

OBJECTIVES

To evaluate the use in an emergency department of a new D-dimer assay (Simplify D-dimer) as a screening test for deep vein thrombosis (DVT).

METHODS

187 outpatients with clinical features suspicious of acute DVT were entered into this study. A Simplify D-dimer test was performed in the emergency department on all patients. A SimpliRED D-dimer test and a semi-automated latex agglutination assay (Auto-D-dimer 700 on a Thromboscreen 400C analyser) were performed in the haematology laboratory. All patients were investigated with contrast venography to confirm or exclude the diagnosis of DVT.

RESULTS

The Simplify test had a sensitivity of 94.1% and a negative predictive value (NPV) of 94.8%. These results compared favourably with the SimpliRED test (sensitivity 74.5%, NPV 89.7%) and the latex agglutination assay (sensitivity 90.2%, NPV 92.2%). This increased sensitivity was at the cost of a lower specificity, the specificity of the three d-dimer tests being Simplify 40.4%, SimpliRED 83.1%, and latex agglutination 43.4%.

CONCLUSIONS

Simplify proved to be a rapid and easy to use test and may be useful for use in the emergency department as part of a diagnostic algorithm for deep vein thrombosis. Further larger scale studies are needed.

Rational use of D-dimer measurement to exclude acute venous thromboembolic disease

Clinical diagnosis of venous thromboembolic (VTE) disease is often inaccurate because signs and symptoms are nonspecific. Testing for the absence of D-dimer levels in the blood of patients with suspected deep venous thrombosis and pulmonary embolism can assist in ruling out these illnesses. Some highly sensitive D-dimer assays have sufficient specificity to assist in the exclusion of VTE disease. Numerous clinical management trials using D-dimer measurement in association with additional diagnostic tests have shown that it is safe to withhold anticoagulant therapy in selected patients with suspected VTE disease who have negative D-dimer assay results. Applying these diagnostic strategies can potentially decrease the need for radiological testing. The simplicity of measuring D-dimer levels creates the potential for misuse. For safe patient management, clinicians must understand the indications for and limitations of D-dimer measurement in the diagnosis of VTE disease.

Diagnosis, investigation, and management of deep vein thrombosis

Deep vein thrombosis is an important cause of morbidity and mortality worldwide, and its clinical diagnosis is unreliable. This article explains current screening and diagnostic methods as well as treatment

Is it safe to withhold anticoagulation based on a single negative color duplex examination in patients with suspected deep venous thrombosis? A prospective 3-month follow-up study

The aim of this study was to evaluate prospectively the clinical short-term outcome of patients with suspected deep venous thrombosis (DVT) and negative duplex investigation and to assess whether it is clinically safe to withhold anticoagulant therapy on the basis of a single negative color duplex examination including the calf veins. The study included a consecutive series of patients with suspected DVT referred for color duplex examination over 1 year. Patients with negative duplex findings (n = 341) were followed up for 3 months clinically and/or by reviewing hospital charts and the official registry of health care and causes of death. In only 1 of the patients was DVT diagnosed following a negative duplex examination. This patient had accentuated symptoms and a thrombus in the peroneal vein was detected at subsequent phlebography. None of the other patients with a negative duplex finding developed signs of, or had treatment initiated for, DVT or pulmonary embolism during the 3-month period after the duplex investigation. Five patients died, but none of the deaths was related to thromboembolism. The results indicate that it is clinically safe to rely on a single negative color duplex examination in patients without any progressing symptoms from the affected limb.

Emergency department D-dimer testing

Since the early 1980s, much attention has been paid to the development of a biochemical marker for venous thromboembolism. D-dimers are derivatives of fibrinolysis and recently have been touted as a means of screening for thromboemoblism. We review the physiologic, pathologic, and chemical bases for this new test, and outline the specific D-dimer assays currently available. We conclude with a discussion of the clinical utility of D-dimer in the evaluation of patients with venous thromboembolism.

Pulmonary embolism: making sense of the diagnostic evaluation

Despite the publication of the Prospective Investigation of Pulmonary Embolism Diagnosis in 1990, the diagnostic evaluation of pulmonary embolism continues to be approached in an inconsistent fashion. The reasons for this are unclear but likely have to do with inadequate methods for predicting pretest probability of disease and the inconvenience and perceived risk of pulmonary angiography. Because pulmonary embolism and its treatment carry substantial risk of morbidity and mortality, a consistent approach to evaluation is desirable. This article reviews large, prospective studies that suggest that it may be unnecessary to diagnose pulmonary embolism with the certainty that pulmonary angiography allows. Finally, the article proposes an algorithm that may be acceptable to patients and clinicians alike if safety is confirmed in future prospective studies.