High-resolution real-time ultrasonography in the diagnosis of deep vein thrombosis

Vascular ultrasonographic findings in canine patients with clinically diagnosed phlebitis

Peripheral vein phlebitis (inflammation) is a relatively frequent complication in dogs, however, published information on the ultrasonographic characteristics is currently lacking. This prospective, observational study describes the ultrasound (US) characteristics of normal canine cephalic veins, and veins with clinical phlebitis. Correlations among US findings and between US findings versus time that the intravenous catheter was in place were investigated. Safety of the US procedure was evaluated. Fifty patients were prospectively recruited for the study and 18 met the final inclusion criteria. Each patient underwent daily US examinations and was assessed for multiple criteria (vascular wall appearance, compressibility, spontaneity of flow, color fill, and presence/absence of filling defects, flow contour, direction, non‐pulsatility). Characteristics of normal canine cephalic veins were as follows: smooth and thin wall, complete compressibility, no flow disturbances, no filling defects, smooth flow contours, and unidirectional, non‐pulsatile flow with no turbulence. Characteristics of cephalic veins with clinical phlebitis were as follows: wall thickening (83%), decreased compressibility (55%), filling defects consistent with intraluminal thrombus (55%), vessel wall hyperechogenicity (44%), and abnormal color Doppler flow (39%). Significant correlations were found between Doppler filling defects and compressibility, Doppler filling defects and presumed thrombosis, and compressibility and presumed thrombosis (P = .001, P = .001, P = .000, respectively). No correlation was found between the US findings and time the intravenous catheter was in place. Findings indicated that duplex and compressibility US are feasible and safe methods for characterizing and monitoring cephalic veins in dogs with clinical phlebitis.

Sparing ultrasound in emergency department patients with suspected deep vein thrombosis by using clinical scores and D-dimer testing

PURPOSE

To evaluate compliance with a management strategy for use in emergency department (ED) patients with suspected deep vein thrombosis (DVT) based on Wells score (WS), D-dimer concentrations, and sonographic (US) examinations.

METHODS

Retrospective and prospective data on risk factors, physical examination findings, D-dimer concentrations, and US results were collected and reviewed. The prevalence of DVT for each WS category and D-dimer level was calculated.

RESULTS

In the retrospective part of the study, 475 consecutive patients were included. Patients' risk for DVT was scored as high (n = 129 [27.2%]), moderate (n = 95 [20%]), or low (n = 251 [52.8%]). D-Dimer test results were available for 34 (7.2%) of the patients. DVT was diagnosed in 105 (22.1%) patients: 99 (76.7%) at high, 4 (4.2%) at moderate, and 2 (0.8%) at low risk. The mean D-dimer concentration was 3,071.7 ng/ml in patients with DVT. In the prospective part of the study, 50 patients were enrolled. Their risk levels for DVT were scored as high (n = 23 [46%]), moderate (n = 7 [14%]), and low (n = 20 [40%]). D-Dimer testing was performed in all patients. The mean D-dimer concentration was 2,966.9 ng/ml in patients with DVT. DVT was diagnosed in 13 (26%) of these 50 patients: 12 (52.2%) at high and 1 (14.3%) at moderate risk for DVT. No patients in the low-risk group and with normal D-dimer concentrations had DVT.

CONCLUSIONS

We identified significant correlation between WS, D-dimer concentration, and diagnosis of DVT on US examination. DVT can be excluded with certainty in patients admitted to the ED with a low-risk score for DVT and a negative D-dimer concentration, thus avoiding the need for performing US examinations. A low level of compliance with this management strategy was found in our ED.

Multimodality imaging of the peripheral venous system

The purpose of this article is to review the spectrum of image-based diagnostic tools used in the investigation of suspected deep vein thrombosis (DVT). Summary of the experience gained by the author as well as relevant publications, regarding vein imaging modalities taken from a computerized database, was reviewed. The imaging modalities reviewed include phlebography, color Doppler duplex ultrasonography (CDDUS), computerized tomography angiography (CTA) and venography (CTV), magnetic resonance venography (MRV), and radionuclide venography (RNV). CDDUS is recommended as the modality of choice for the diagnosis of DVT. A strategy combining clinical score and D-dimer test refines the selection of patients. Phlebography is reserved for discrepant noninvasive studies.

Clavicular fracture and upper-extremity deep venous thrombosis

Upper-extremity deep venous thrombosis (DVT) is considered an uncommon clinical event with considerable potential for morbidity. This article presents a case of upper-extremity DVT following a clavicular fracture. A 25-year-old man presented with pain and distortion of the left midclavicular area after falling on his left shoulder during martial arts practice. Following physical examination and radiography, he was diagnosed with a simple displaced clavicle fracture at the middle third. The patient had no previous surgery or medical problem, and did not smoke. No family history of blood clotting disorders were present and neurovascular examination appeared normal on the symmetric contralateral side. A figure-of-8 bandage was applied to support the arm and the patient was discharged. One week later, he returned with swelling and severe pain in his left arm. On examination, a DVT was suspected and the figure-of-8 brace was removed. A Doppler ultrasonography was performed and the presence of a thrombus extending from the brachial axillary veins to the distal subclavian vein with no flow in that segment was revealed. The patient was placed in a sling instead of a figure-of-8 bandage to immobilize the arm, while anticoagulation therapy with enoxaparin was started (1 mg/kg every 12 hours, 80 mg subcutaneous daily for 3 months). The swelling was reduced after 5 days. At 2-week follow-up, the patient had no pain and the swelling had completely disappeared.

Current approaches and controversial issues in the diagnosis of deep vein thrombosis via duplex Doppler ultrasound

Duplex and color Doppler sonography (DUS) is currently the technique of choice for the diagnosis of deep venous thrombosis (DVT) in symptomatic patients, because it has proven safe and cost-effective, with a very high sensitivity and specificity (96% and 98%, respectively) for the diagnosis of proximal DVT. Several issues regarding its method and clinical indications remain controversial, however. Although isolated calf vein thrombosis does not seem to have a significant adverse outcome in the short term, scanning the calf only in patients with localized symptoms or signs is cost-effective. Bilateral examination is indicated in high-risk patients or when screening asymptomatic patients. When negative, a complete DUS examination of the proximal and distal veins, at least down to the level of the popliteal trifurcation, allows withholding anticoagulant therapy without the risk of major complications. This examination may be repeated if signs or symptoms worsen. Some populations of asymptomatic patients at high risk of DVT may benefit from DUS screening. Bilateral DUS examination of lower limb veins should be performed as the initial examination in the workflow of pulmonary embolism only in patients with risk factors for DVT. Recurrent thrombosis is a challenging diagnosis for all imaging modalities. A diagnostic strategy combining clinical probability score and D-dimer test may refine the selection of patients. The pitfalls and limitations of venous DUS are related to vein anatomy, flow changes, technical issues, and operator expertise.

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.

Reoperative venous access

The maintenance of long-term venous access is critical to the livelihood of children in a variety of clinical situations, especially those who are dependent on parenteral nutrition. Whereas the traditional routes of either peripheral or central venous access are initially adequate, most of these sites eventually succumb to the pitfalls associated with long-term venous access. This review provides a comprehensive and multidisciplinary approach to the management of reoperative venous access with regard to preoperative planning and imaging and specific techniques in interventional radiology and surgery.

Diagnosis of acute lower limb deep venous thrombosis with ultrasound: trends and controversies

Acute deep venous thrombosis of the lower limb is a common and threatening condition whose clinical diagnosis is known to be unreliable. Sonography has gradually superseded venography as the primary diagnostic procedure. A review of the medical literature shows that sonography offers a high level of sensitivity and specificity in symptomatic patients but suffers from a lack of sensitivity at the calf level and in asymptomatic patients. Technologic progress, as well as increased operator experience, may improve sensitivity. Nevertheless, several critical issues remain unresolved, such as the significance of free-floating thrombi, the usefulness of calf and bilateral examination, the criteria that are essential to the diagnosis, the risk of compression sonography, and sonography's role in the direct detection of venous emboli.

Image-directed Doppler ultrasound in the diagnosis of lower-limb venous insufficiency

Ninety-eight legs in 73 patients were evaluated with image-directed Doppler ultrasound for suspected chronic venous insufficiency. Examinations of the entire venous system were performed to determine lumen patency and valvular competence. Reflux during Valsalva maneuver in the femoral and great saphenous vein, and, after release of distal compression in the popliteal vein, indicated valvular incompetence. Twenty limbs had normal veins; Baker's cysts were found in three. Superficial venous insufficiency was found in 25 cases. Deep reflux, either alone or in combination with superficial reflux, was the predominant pathological feature (53 legs). Photoplethysmographic studies of the veins were performed on 24 limbs. Image-directed Doppler ultrasound was more successful in defining the exact site of venous incompetence and in detecting nonvenous pathology. By the combination of real-time imaging of the vein with gated Doppler sonography of flow, image-directed Doppler sonography is becoming the method of choice for the investigation of chronic venous insufficiency.

Duplex ultrasound diagnosis of lower limb deep venous thrombosis

To compare a non-invasive technique with contrast venography in the diagnosis of lower limb deep venous thrombosis (DVT), 355 patients (380 limbs) were examined over 15 months, using Duplex ultrasound. During this period, ascending venograms were performed in 53 of these patients (56 limbs) and the results were compared. Duplex detection of intraluminal thrombus was based on venous compressibility, Doppler-derived flow spectra, and visualization of thrombus within the lumen. Venography was designated the 'gold standard'. Duplex scanning had a sensitivity of 90.9%, and specificity of 91.3% in diagnosing DVT anywhere in the lower limb. Sensitivity, specificity, and accuracy were best in the femoral segment (95.2%, 100%, 98.2%, respectively), and fell slightly in the more distal limb: popliteal segment (90.4%, 97.1% and 94.6%), and calf veins (88.8%, 92.0% and 90.4%). These results indicate that duplex scanning produces sufficiently accurate data in the diagnosis of lower limb DVT to warrant its clinical use. It provides both the facility for diagnosis without the risks of contrast venography, and permits repeated imaging to follow the immediate progression of disease and efficacy of treatment.