Distribution of thrombi in acute lower extremity deep venous thrombosis: implications for sonography and CT and MR venography

Resident performed two-point compression ultrasound is inadequate for diagnosis of deep vein thrombosis in the critically III

Doppler ultrasonography is a standard in diagnosis of deep vein thrombosis (DVT) but is often delayed. Clinician-performed focused vascular sonography (FVS) has proven to accurately diagnose DVT in the ambulatory and emergency room settings. Whether trained medical residents can perform quality FVS in the critically ill is unknown. Medical residents were trained in a 2-hour module in FVS assessing for complete compressibility of common femoral and popliteal veins. Residents imaged consecutive medical ICU and intermediate care patients awaiting comprehensive, sonographer-performed and radiologist-interpreted examinations. Sensitivity, specificity, positive and negative predictive values of the focused examination were calculated against the comprehensive study. Fleiss Kappa (κ), the degree of agreement between resident and radiologist, was calculated. Time savings was measured. Nineteen residents performed 143 studies on 75 patients. Twelve patients had above-the-knee DVTs, a prevalence of 16 %. All 6 common femoral and 7 of 9 popliteal vein DVTs were identified. None of 6 isolated superficial femoral DVTs were identified. Sensitivity for above-the-knee DVT was 63 %, specificity 97 %. Sensitivity for common femoral and popliteal DVT was 86 %, specificity 97 %. Residents showed substantial agreement with radiologists for diagnosis of DVT (κ = 0.70, SE 0.114, p < 0.001).Time from order of a formal ultrasound to a radiologist's read averaged 14.7 h. The two-point compression ultrasound method demonstrated insufficient sensitivity in a cohort of critically ill medical patients due to a high-incidence of superficial femoral DVT. However, residents demonstrated substantial agreement with radiologists for the diagnosis of clinically relevant DVT after a 2-hour course. FVS should include the superficial femoral vein and is associated with a significant time savings.

Incidence of ipsilateral postoperative deep venous thrombosis in the amputated lower extremity of patients with peripheral obstructive arterial disease

OBJECTIVE

Patients undergoing amputation of the lower limb due to peripheral arterial disease (PAD) are at risk of developing deep venous thrombosis (DVT). Few studies in the research literature report the incidence of DVT during the early postoperative period or the risk factors for the development of DVT in the amputation stump. This prospective study evaluated the incidence of DVT during the first 35 postoperative days in patients who had undergone amputation of the lower extremity due to PAD and its relation to comorbidities and death.

METHODS

Between September 2004 and March 2006, 56 patients (29 men), with a mean age of 67.25 years, underwent 62 amputations, comprising 36 below knee amputations (BKA) and 26 above knee amputations (AKA). Echo-Doppler scanning was performed preoperatively and on postoperative days 7 and 31 (approximately). All patients received acetylsalicylic acid (100 mg daily) preoperatively and postoperatively, but none received prophylactic anticoagulation.

RESULTS

DVT occurred in 25.8% of extremities with amputations (10 AKA and 6 BKA). The cumulative incidence in the 35-day postoperative period was 28% (Kaplan-Meier). There was a significant difference (P = .04) in the incidence of DVT between AKA (37.5%) and BKA (21.2%). Age >or=70 years (48.9% vs 16.8%, P = .021) was also a risk factor for DVT in the univariate analysis. Of the 16 cases, 14 (87.5%) were diagnosed during outpatient care. The time to discharge after amputation was averaged 6.11 days in-hospital stay (range, 1-56 days). One symptomatic nonfatal pulmonary embolism occurred in a patient already diagnosed with DVT. There was no relation between other comorbidities and DVT. The multivariate analysis showed no association between risk factors and the occurrence of DVT in the amputated extremity. DVT ipsilateral to the amputation did not influence the mortality rate (9.7%).

CONCLUSION

The incidence of DVT in the early postoperative period (<or=35 days) was elevated principally in patients aged >or=70 years and for AKA. Patients with PAD who have recently undergone major amputations should be considered at high risk for DVT, even after hospital discharge. Given the high rate of postoperative DVT observed in this study, we now recommend prophylactic anticoagulation for these patients, but further study is needed to determine the optimal duration and efficacy of this treatment.

Ultrasound Evaluation of the Lower Extremity Veins

Over the past 2 decades venous ultrasonography has become the standard primary imaging technique for the initial evaluation of patients for whom there is clinical suspicion of deep venous thrombosis (DVT) of the lower extremity veins. This article addresses the role of duplex ultrasonography and color Doppler ultrasonography in today's clinical practice for the evaluation of patients suspected of harboring a thrombus in their lower extremity veins. It reviews the clinical presentation and differential diagnoses, technique, and diagnostic criteria for acute and chronic DVT. In addition, it addresses the sonographic evaluation of venous insufficiency.

Pilot study on the comprehensive economic costs of major trauma: Consequential costs are well in excess of medical costs

BACKGROUND

Trauma care is expensive. However, reliable data on the exact lifelong costs incurred by a major trauma patient are lacking. Discussion usually focuses on direct medical costs--underestimating consequential costs resulting from absence from work and permanent disability.

METHODS

Direct medical costs and consequential costs of 63 major trauma survivors (ISS >13) at a Swiss trauma center from 1995 to 1996 were assessed 5 years posttrauma. The following cost evaluation methods were used: correction cost method (direct cost of restoring an original state), human capital method (indirect cost of lost productivity), contingent valuation method (human cost as the lost quality of life), and macroeconomic estimates.

RESULTS

Mean ISS (Injury Severity Score) was 26.8 +/- 9.5 (mean +/- SD). In all, 22 patients (35%) were disabled, causing discounted average lifelong total costs of USD 1,293,800, compared with 41 patients (65%) who recovered without any disabilities with incurred costs of USD 147,200 (average of both groups USD 547,800). Two thirds of these costs were attributable to a loss of production whereas only one third was a result of the cost of correction. Primary hospital treatment (USD 27,800 +/- 37,800) was only a minor fraction of the total cost--less than the estimated cost of police and the judiciary. Loss of quality of life led to considerable intangible human costs similar to real costs.

CONCLUSIONS

Trauma costs are commonly underestimated. Direct medical costs make up only a small part of the total costs. Consequential costs, such as lost productivity, are well in excess of the usual medical costs. Mere cost averages give a false estimate of the costs incurred by patients with/without disabilities.

Current DVT imaging

Accurate diagnosis of deep venous thrombosis (DVT) is very difficult, and imaging plays a crucial role in the diagnosis or exclusion of DVT. The initial test of choice for diagnosis of acute thigh as well as upper extremity DVT is ultrasound, because of its high accuracy, relatively low cost, portability, and lack of ionizing radiation. In patients who are undergoing CT pulmonary angiography for suspected pulmonary embolism, CT venography can be performed as part of the examination, for comprehensive evaluation of the venous system in the legs, abdomen, and pelvis. MR has a problem-solving role, and conventional venography is now limited to specific scenarios including evaluation of central DVT in the upper extremities, as a prelude to intervention for thrombolysis/thrombectomy, and prior to placement of an inferior vena cava filter. This article discusses the imaging findings of DVT, and the role of these imaging examinations in the evaluation of patients with suspected DVT.

CT venography in suspected pulmonary thromboembolism

Pulmonary embolism (PE) and deep venous thrombosis (DVT) are a continuum and are difficult to diagnose clinically. Combined CT venography and pulmonary angiography (CTVPA) is a single examination that combines multidetector CT pulmonary angiography (CTPA) and CT venography (CTV) of the abdomen, pelvis, and lower extremities, providing "one-stop shopping" for venous thromboembolism without additional venipuncture or i.v. contrast, and it adds only a few additional minutes to scanning time. CTVPA rapidly and accurately examines the deep veins, reveals the presence, absence, and extent of deep venous thrombosis, serves as a baseline, and helps guide patient management. Multiple investigators have reported a high degree of accuracy when CTV is compared with venous ultrasound. There are some pitfalls in image interpretation, especially with regard to mixing artifacts, and there are continuing controversies as to exactly which parts of the abdomen, pelvis, and legs should be scanned routinely, the ideal timing of CTV acquisition relative to contrast injection, and the slice thickness and gap, if any, that should be used.

Variations in lower limb venous anatomy: implications for US diagnosis of deep vein thrombosis

PURPOSE

To retrospectively review bilateral venograms free of thrombus to evaluate the frequency and types of variations seen in venous anatomy.

MATERIALS AND METHODS

A retrospective review of 404 bilateral (808 limbs) lower limb venograms obtained from medical patients participating in a thromboprophylaxis clinical trial and found to be free of thrombus was performed. Venograms were evaluated according to predetermined criteria for the presence of duplication of vessels and inter- and intraindividual variations in venous anatomy. Variations were assessed with analysis of variance and chi2 tests.

RESULTS

Two vessels were seen in the popliteal fossa on 337 (42%) of 808 venograms, and 41 (5%) were true duplicated popliteal veins. There were 253 (31%) duplicated superficial femoral veins (SFVs), with 12 (1.5%) being complex duplicated systems. Of 265 duplicated SFVs, 138 (52%) began in the midthigh region and 80 (30%), in the adductor canal region. The duplicated vessel was medial to the main SFV in 122 (46%), lateral in 131 (49%), and both (ie, triplications) in 12 (4.5%). The length of the duplicated SFV ranged from 1 to 35 cm; 6-15 cm was the most common length in 162 (62%) SFVs. There was no significant association between the incidence of anatomic variations and age or sex (P >.1). The presence of multiple vessels in one leg was strongly correlated with the probability of occurrence in the other leg (P <.001).

CONCLUSION

Variations in lower limb venous anatomy are common and have important implications for the US diagnosis of deep vein thrombosis.

CT for thromboembolic disease

Pulmonary embolism (PE) and deep venous thrombosis (DVT) constitute the two clinical manifestations of venous thromboembolic disease (VTE). The recent innovation of computed tomography venography (CTV) in conjunction with CT pulmonary arteriography (CTPA) provides a single noninvasive diagnostic test that can evaluate both components of VTE. PE is often an underestimated, underdiagnosed, and, consequently, undertreated disease entity. Herein, we review the epidemiology of thromboembolic disease, the diagnostic algorithm used in evaluation of patients with suspected VTE, and protocols for performing CTPA and CTV. Interpretation of these examinations is discussed in detail, because CTPA may pose new challenges to the practicing radiologist.

Combined CT venography and pulmonary angiography: a comprehensive review

The combination of computed tomographic (CT) venography and pulmonary angiography (CTVPA) was initially described in 1998 as a single comprehensive noninvasive imaging examination for suspected thromboembolic disease. It allowed the identification of pulmonary embolism as well as deep venous thrombosis (DVT) in the abdomen, pelvis, thighs, and calves. The venographic portion of CTVPA has now been studied by multiple researchers and has been shown to be an accurate imaging study for the thigh veins in comparison with lower extremity sonography. In contrast to sonography, however, CTVPA readily and rapidly permits evaluation of the inferior vena cava, the pelvic veins, the calf veins, and all of the superficial venous system. Complex venous anatomy can be surveyed, an additional sonographic study is not required, and only a few extra minutes and images are required over and above CT pulmonary angiography. A review of 957 recent cases of suspected pulmonary embolism examined with CTVPA revealed an overall 10.5% frequency of DVT, with a nearly equal distribution of thrombosis at the common femoral, superficial femoral, popliteal, and deep calf veins. Although a variety of protocols for CTVPA may be implemented, including a contiguous helical acquisition, obtaining 5- or 10-mm-thick images every 4 cm provides a high degree of accuracy and decreases overall radiation dose.

Computed tomographic venography is specific but not sensitive for diagnosis of acute lower-extremity deep venous thrombosis in patients with suspected pulmonary embolus

PURPOSE

Duplex ultrasound scanning (US) is the accepted standard means of diagnosis for lower-extremity suprageniculate deep venous thrombosis (LE-DVT). Computed tomographic venography (CTV) has been proposed as an alternative modality for diagnosis of LE-DVT in patients with suspected pulmonary embolism (PE). This study compared CTV with US as a means of diagnosing acute LE-DVT.

METHODS

A retrospective review of US and CTV scans from 136 patients with suspected PE who underwent both studies to exclude acute LE-DVT at a single institution was performed. Studies were reviewed and coded in a blinded manner. US was considered to be the reference test. Direct costs of each study were determined by using commercial software.

RESULTS

The sensitivity and specificity rates of CTV were 71% and 93%, respectively. The positive predictive value, negative predictive value, and accuracy rates of CTV were 53%, 97%, and 90%, respectively. DVT localization was the same in eight of 10 cases in which the results of both US and CTV were positive. CTV costs and charges per study were greater than those of US by $46.88 and $602.00, respectively.

CONCLUSION

CTV is specific, but has a lower sensitivity rate and positive predictive value for the diagnosis of acute LE-DVT compared with US. Additionally, CTV is more costly than US scanning. Because of the lower sensitivity rate and positive predictive value and the increased cost of CTV, US remains the screening study of choice in cases of suspected acute LE-DVT.