Is color-flow duplex a good diagnostic test for detection of isolated calf vein thrombosis in high-risk patients?

Direct oral anticoagulants decrease treatment failure for acute lower extremity deep venous thrombosis

OBJECTIVE

Optimal medical therapy for acute lower extremity deep venous thrombosis (DVT) remains an enigma. While clinical trials demonstrate non-inferiority with an oral anti-Xa inhibitor, or direct oral anticoagulant (DOAC), versus combined low-molecular weight heparin (LMWH) and oral vitamin K antagonist (VKA), the most effective regimen remains to be determined.

METHODS

This study is a single-center retrospective cohort study from October 2014 to December 2015 of patients with a diagnosis of acute DVT and subsequent serial lower extremity venous duplex. Demographics, medical history, medications, serial ultrasound findings, as well as the primary anticoagulant used for treatment were collected and analyzed by two independent data extractors. Treatment failure was defined as any new DVT or progression of an existing DVT within 3 months of diagnosis of the index clot. Risk factors for treatment failure were assessed using standard odds ratios and Fischer's exact test.

RESULTS

Among 496 patients with an acute lower extremity DVT, 54% (n = 266) were men, mean age was 61 years, 35% (n = 174) involved the popliteal or more proximal segments, and 442 had documentation of the primary treatment for DVT: 20% (n = 90) received nothing; 20% (n = 92) received an oral VKA; 34% (n = 149) received a DOAC; 20% (n = 90) received LMWH; and 5% (n = 21) received another class of anticoagulant. Within 3 months, 21% (n=89 out of 427) had treatment failure defined as any new DVT or progression of prior DVT. Patients treated with a DOAC were less likely to experience treatment failure when compared with any other treatment (odds ratio 0.43; 95% confidence intervals [0.23, 0.79]; p = 0.0069) and when compared with traditional oral VKA (OR 0.44; 95% CI [0.21, 0.92]; p = 0.029). None of prior history of DVT, pulmonary embolism, thrombophilia, renal insufficiency, hepatic insufficiency, cancer, or antiplatelet therapy correlated with treatment failure. Treatment outcome did not correlate with being on any anticoagulation versus none (p = 0.74), nor did it correlate with the duration of treatment (<3 months versus ≥3 months) (p = 0.42). Proximal and distal DVTs showed no difference in treatment failure (19% versus 22%, respectively; p = 0.43).

CONCLUSION

In summary, the use of a DOAC for acute lower extremity DVT yielded better overall outcomes and fewer treatment failures at 3 months as compared to traditional oral VKA therapy based on serial duplex imaging.

The rate of missed diagnosis of lower-limb DVT by ultrasound amounts to 50% or so in patients without symptoms of DVT: A meta-analysis

BACKGROUND

To assess whether the ultrasound (US) is a reliable approach in detecting lower-limb deep-vein thrombosis (DVT) in patients without symptoms of DVT.

METHODS

The research team performed a systematic search in PubMed, Ovid, Cochrane, and Web of Science without language or date restrictions. Full-text reports on prospective diagnostic studies involve the detection of lower-limb proximal and distal DVT in patients without symptoms of DVT using US and venography. A meta-analysis was performed using Meta-DiSc (version 1.4), providing the pooled sensitivity, specificity, positive (LR+) and negative (LR-) likelihood ratios of the detection accuracy of US. There were 4 different classes of subgroup analysis-the class of patients stratified by location of US exam (proximal, distal, whole leg), the class stratified by technique (color/doppler, compression, both modalities), the class stratified by kind of surgery (orthopedic, otherwise hospitalized) and the class stratified by era of publishing (1980s, 1990s, 2000s). The study quality and the risk of bias were evaluated using QUADAS-2, with heterogeneity was assessed and quantified by the Q score and I statistics, respectively.

RESULTS

The meta-analysis included 26 articles containing 41 individual studies with a total of 3951 patients without symptoms of DVT. Using venography as the gold standard, US for proximal DVT had a pooled sensitivity of 59% (95% confidence interval (CI) = 51%-66%) and a pooled specificity of 98% (95% CI = 97%-98%), US for distal DVT had a poor sensitivity of 43% (95% CI = 38%-48%) and a pooled specificity of 95% (95% CI = 94%-96%), US for whole-leg DVT had a pooled sensitivity of 59% (95% CI = 54%-64%) and a pooled specificity of 95% (95% CI = 94%-96%), US for post-major orthopedic surgery patients had a pooled sensitivity of 52% (95% CI = 49%-55%), and US for other types of patients had a pooled sensitivity of 58% (95% CI = 43%-72%). Pure compression technique for DVT had a poor sensitivity of 43% (95% CI = 39%-48%), pure color/doppler technique for DVT had a pooled sensitivity of 58% (95% CI = 53%-63%), compression and color/doppler technique for DVT had a pooled sensitivity of 61% (95% CI = 48%-74%).

CONCLUSION

US could be a useful tool for diagnosing DVT, but it has a lower positive rate and a higher false negative rate. The rate of missed diagnosis of lower-limb DVT by US amounts to 50% or so in the patients without symptoms of DVT. The negative results do not preclude the possibility of DVT and if appropriate heightened surveillance and continued monitoring or try a more accurate inspection method is warranted. The whole leg evaluation and color/doppler technique should be the preferred approach.

Management of Venous Thromboembolisms: Part I. The Consensus for Deep Vein Thrombosis

Deep vein thrombosis (DVT) is a potentially catastrophic condition because thrombosis, left untreated, can result in detrimental pulmonary embolism. Yet in the absence of thrombosis, anticoagulation increases the risk of bleeding. In the existing literature, knowledge about the epidemiology of DVT is primarily based on investigations among Caucasian populations. There has been little information available about the epidemiology of DVT in Taiwan, and it is generally believed that DVT is less common in Asian patients than in Caucasian patients. However, DVT is a multifactorial disease that represents the interaction between genetic and environmental factors, and the majority of patients with incident DVT have either inherited thrombophilia or acquired risk factors. Furthermore, DVT is often overlooked. Although symptomatic DVT commonly presents with lower extremity pain, swelling and tenderness, diagnosing DVT is a clinical challenge for physicians. Such a diagnosis of DVT requires a timely systematic assessment, including the use of the Wells score and a D-dimer test to exclude low-risk patients, and imaging modalities to confirm DVT. Compression ultrasound with high sensitivity and specificity is the front-line imaging modality in the diagnostic process for patients with suspected DVT in addition to conventional invasive contrast venography. Most patients require anticoagulation therapy, which typically consists of parenteral heparin bridged to a vitamin K antagonist, with variable duration. The development of non-vitamin K oral anticoagulants has revolutionized the landscape of venous thromboembolism treatment, with 4 agents available,including rivaroxaban, dabigatran, apixaban, and edoxaban. Presently, all 4 drugs have finished their large phase III clinical trial programs and come to the clinical uses in North America and Europe. It is encouraging to note that the published data to date regarding Asian patients indicates that such new therapies are safe and efficacious. Ultimately, our efforts to improve outcomes in patients with DVT rely on the awareness in the scientific and medical community regarding the importance of DVT.

KEY WORDS

Combination therapy; Hypertension; α1-blocker.

Strategies for diagnosis and prevention of venous thromboembolism during pregnancy

Pregnancy and the postpartum period have an increased incidence of venous thromboembolism (VTE). The condition is unique during this period for several reasons. Primarily, because there is complexity in diagnosing this condition in view of altered physiology and preexisting edema in pregnancy and also because there are restrictions on the use of certain drugs and a need for vigilant monitoring of anticoagulant activities of drugs during the period. The problem is compounded and assumes the highest order of significance since two lives are involved and all the investigations and management done should also take into account the potential adverse effects on the foetus. In order to prevent the development of VTE during pregnancy, sound clinical evaluation for risk factors, risk stratification, and optimal use of resource both mechanical and pharmacological is necessary. This paper details strategies in preventing development of deep vein thrombosis and treatment of VTEs.

Venous thromboembolism in pregnancy

In Western nations, venous thromboembolism (VTE) is an important cause of morbidity and the most common cause of maternal death during pregnancy and the puerperium. Pregnancy is a hypercoagulable state in which coagulation is activated and thrombolysis inhibited. This prothrombotic risk is compounded when hereditary and acquired thrombophilias and other prothrombotic risk factors are present. The risk of venous thrombotic events is increased fivefold during pregnancy and 60-fold in the first 3 months after delivery (postpartum period) compared with nonpregnant women. Many of the signs and symptoms of VTE overlap those of a normal pregnancy, which complicates the diagnosis. Patients with history of previous VTE should use graduated compression stockings throughout pregnancy and the puerperium, and should receive postpartum anticoagulant prophylaxis. The indications for antepartum anticoagulant prophylaxis are somewhat controversial. This article reviews the management of VTE during pregnancy and in the postpartum period.

The RUSH exam: Rapid Ultrasound in SHock in the evaluation of the critically lll

The RUSH exam (Rapid Ultrasound in SHock examination), presented in this article, represents a comprehensive algorithm for the integration of bedside ultrasound into the care of the patient in shock. By focusing on a stepwise evaluation of the shock patient defined here as "Pump, Tank, and Pipes," clinicians will gain crucial anatomic and physiologic data to better care for these patients.

Evaluation of deep vein thrombosis with multidetector row CT after orthopedic arthroplasty: a prospective study for comparison with Doppler sonography

Objective

This prospective study evaluated the ability of indirect 16-row multidetector CT venography, in comparison with Doppler sonography, to detect deep vein thrombosis after total hip or knee replacement.

Materials and Methods

Sixty-two patients had undergone orthopedic replacement surgery on a total of 30 hip joints and 54 knee joints. The CT venography (scan delay time: 180 seconds; slice thickness/increment: 2/1.5 mm) and Doppler sonography were performed 8 to 40 days after surgery. We measured the z-axis length of the beam hardening artifact that degraded the image quality so that the presence of deep vein thrombosis couldn't be evaluated on the axial CT images. The incidence and location of deep vein thrombosis was analyzed. The diagnostic performance of the CT venograms was evaluated and compared with that of Doppler sonography as a standard of reference.

Results

The z-axis length (mean±standard deviation) of the beam hardening artifact was 4.5 ± 0.8 cm in the arthroplastic knees and 3.9 ± 2.9 cm in the arthroplastic hips. Deep vein thrombosis (DVT) was found in the popliteal or calf veins on Doppler sonography in 30 (48%) of the 62 patients. The CT venography has a sensitivity, specificity, positive predictive value, negative predictive value and accuracy of 90%, 97%, 96%, 91% and 94%, respectively.

Conclusion

The ability of CT venography to detect DVT was comparable to that of Doppler sonography despite of beam hardening artifact. Therefore, CT venography is feasible to use as an alternative modality for evaluating postarthroplasty patients.

Literature search parameters marginally improved the pooled estimate accuracy for ultrasound in detecting deep venous thrombosis

BACKGROUND AND OBJECTIVES

Data collection remains of utmost importance to avoid publication bias in systematic reviews. Our objectives were to compare search strategies with and without methodological terms in Medline, to find out how other databases complement Medline, and how these strategies affect the pooled estimates of the accuracy.

STUDY DESIGN AND SETTING

A study was eligible if it prospectively compared ultrasound to venography for the diagnosis of deep venous thrombosis in the lower limbs. All relevant articles found with all databases, searched from 1966 through 2003, constitute the reference standard. Sensitivity was defined as the proportion of relevant studies found by Medline searches divided by the total number of articles in the reference standard.

RESULTS

Of a total of 1,473 citations, 237 abstracts were included. The sensitivity of strategies without methodological terms was higher (96%) than those with (95%, 76%, and 95%). Searches of multiple databases found seven articles not found with Medline. Searches of congress proceedings (International Society of Thrombosis and Haemostasis) found three abstracts not published in full. The diagnostic odds ratio OR was 5.66 (95% confidence interval CI = 4.84-6.48) when multiple databases were searched and 5.57 (95% CI = 3.49-7.65) when only English-language articles in Medline were identified.

CONCLUSION

Medline searches combining free text and MeSH terms were more sensitive. Single Medline search affects only marginally the pooled estimate accuracy.

High sensitivity with color duplex sonography in thrombosis screening after ankle fracture surgery

BACKGROUND

Phlebography is regarded as the reference standard for diagnosing asymptomatic deep vein thrombosis (DVT) in studies of thromboprophylaxis. However, technical advances with noninvasive color duplex sonography (CDS) have made this procedure an interesting alternative.

OBJECTIVES

The objective of the present prospective study was to compare the sensitivity and specificity of CDS with those of phlebography.

PATIENTS

The first 180 consecutive patients included in a larger randomized trial for prolonged thromboprophylaxis were subject to unilateral CDS and to phlebography after ankle fracture surgery. The patients were examined 6 weeks after surgery, all examinations being evaluated blindly. After patient drop outs and exclusions, 144 patients were left for analysis.

RESULTS

Phlebography and CDS examinations were inconclusive or were not completed for 19% of these patients (28/144). DVT was diagnosed by phlebography in 21% (24/116) of the remaining patients. Most of the thrombi were isolated calf DVTs (18/24). In contrast, DVT was diagnosed by CDS in 31% of these patients (36/116): only one case diagnosed by phlebography was missed by CDS. The specificity of CDS is thus 86% and its sensitivity is 96%. The positive predictive value is 64%, and the negative predictive value is 99%.

CONCLUSIONS

CDS is a safe method for detecting asymptomatic distal DVT. It has a high sensitivity and high negative predictive value, which means that the method is highly reliable to rule out DVT. Our results indicate that CDS could be considered as an alternative method for DVT screening.

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.

Prevention of venous thromboembolism: the Seventh ACCP Conference on Antithrombotic and Thrombolytic Therapy

This article discusses the prevention of venous thromboembolism (VTE) and is part of the Seventh American College of Chest Physicians Conference on Antithrombotic and Thrombolytic Therapy: Evidence-Based Guidelines. Grade 1 recommendations are strong and indicate that the benefits do, or do not, outweigh risks, burden, and costs. Grade 2 suggests that individual patients' values may lead to different choices (for a full understanding of the grading see Guyatt et al, CHEST 2004; 126:179S-187S). Among the key recommendations in this chapter are the following. We recommend against the use of aspirin alone as thromboprophylaxis for any patient group (Grade 1A). For moderate-risk general surgery patients, we recommend prophylaxis with low-dose unfractionated heparin (LDUH) (5,000 U bid) or low-molecular-weight heparin (LMWH) [< or = 3,400 U once daily] (both Grade 1A). For higher risk general surgery patients, we recommend thromboprophylaxis with LDUH (5,000 U tid) or LMWH (> 3,400 U daily) [both Grade 1A]. For high-risk general surgery patients with multiple risk factors, we recommend combining pharmacologic methods (LDUH three times daily or LMWH, > 3,400 U daily) with the use of graduated compression stockings and/or intermittent pneumatic compression devices (Grade 1C+). We recommend that thromboprophylaxis be used in all patients undergoing major gynecologic surgery (Grade 1A) or major, open urologic procedures, and we recommend prophylaxis with LDUH two times or three times daily (Grade 1A). For patients undergoing elective total hip or knee arthroplasty, we recommend one of the following three anticoagulant agents: LMWH, fondaparinux, or adjusted-dose vitamin K antagonist (VKA) [international normalized ratio (INR) target, 2.5; range, 2.0 to 3.0] (all Grade 1A). For patients undergoing hip fracture surgery (HFS), we recommend the routine use of fondaparinux (Grade 1A), LMWH (Grade 1C+), VKA (target INR, 2.5; range, 2.0 to 3.0) [Grade 2B], or LDUH (Grade 1B). We recommend that patients undergoing hip or knee arthroplasty, or HFS receive thromboprophylaxis for at least 10 days (Grade 1A). We recommend that all trauma patients with at least one risk factor for VTE receive thromboprophylaxis (Grade 1A). In acutely ill medical patients who have been admitted to the hospital with congestive heart failure or severe respiratory disease, or who are confined to bed and have one or more additional risk factors, we recommend prophylaxis with LDUH (Grade 1A) or LMWH (Grade 1A). We recommend, on admission to the intensive care unit, all patients be assessed for their risk of VTE. Accordingly, most patients should receive thromboprophylaxis (Grade 1A).

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.

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.

Deep venous thrombosis in postoperative vascular surgical patients: a frequent finding without prophylaxis

PURPOSE

The place of routine perioperative thromboprophylaxis for vascular surgical patients remains controversial, because the incidence of postoperative deep venous thrombosis (DVT) is said to be quite low. This study was designed to measure the incidence of lower limb DVT after vascular surgical procedures.

METHODS

All consenting, consecutive patients who came to a metropolitan veterans hospital for abdominal or lower-limb arterial surgery were studied. Clinical and operative data were recorded. Lower-limb color flow duplex scans were performed before and after surgery.

RESULTS

Fifty patients, age 75 +/- 1 (mean +/- SEM) years, were studied. Abdominal procedures were performed on 22 patients, and lower-limb procedures were performed on 28 patients. A postoperative DVT was noted in 14 patients (32%), 9 patients (41%) in the abdominal surgical group and 5 patients (18%) in the lower-limb group. Calf DVTs were four times more common than femoropopliteal DVTs.

CONCLUSION

The incidence of postoperative lower-limb DVTs in this cohort of vascular surgical patients was high. The small size of the study population precludes generalized recommendations, but the results indicate an urgent need for definitive investigation.