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

Bilateral lower limb examinations for deep vein thrombosis: A single-centre pilot study comparing request and report parameters for bilateral and unilateral referrals

INTRODUCTION

Deep vein thrombosis (DVT) is a common pathology with significant morbidity and mortality, often occurring in the lower limb. Ultrasound is the modality of choice for diagnosis of DVT, but all guidance in the United Kingdom assumes a single leg referral. Few studies have addressed the question of bilateral referrals and bilateral DVTs, and it is not known how these should be included in ultrasound protocols. This study aims to compare the request and report parameters of bilateral examinations with those for single leg examinations over a six-month period.

METHODS

A single-centre feasibility study collected data on all single and bilateral leg examinations performed by sonographers, over a six-month period at a small general hospital. Data collected for each examination included the referral and report findings. These were compared using basic statistical methods to compare DVT yield by laterality, referrer, DVT site, and patient factors.

RESULTS

Six hundred and thirty examinations were included, eighteen of which were bilateral examinations. Although the bilateral leg cohort was small, there were significant differences in DVT yield between the groups, with single leg referrals more than eight times more likely to demonstrate a DVT at ultrasound.

CONCLUSION

In a context of limited ultrasound resource, the low DVT yield of bilateral examinations has implications for service design. Further data collection will be needed to validate initial results, and to establish suitable criteria for acceptance of bilateral DVT referrals.

IMPLICATIONS FOR PRACTICE

Low yield of DVTs in bilateral examinations can be validated via further research. Bilateral examinations can be explicitly included in DVT service design.

Emergency medicine residents' learning curve in diagnosing deep vein thrombosis with 3-point venous point-of-care ultrasound

BACKGROUND

Many cases of deep vein thrombosis (DVT) are diagnosed in the emergency department, and abbreviated lower extremity venous point-of-care ultrasound (POCUS) has already shown an accuracy comparable to that of specialists. This study aimed to identify the learning curve necessary for emergency medicine (EM) residents to achieve expertise-level accuracy in diagnosing DVT through a 3-point lower extremity venous POCUS.

METHODS

This prospective study was conducted at an emergency department between May 2021 and October 2022. Four EM residents underwent a one-hour POCUS training session and performed DVT assessments in participants with DVT symptoms or confirmed pulmonary embolism. POCUS was performed at three proximal lower extremity sites to evaluate the thrombi presence and vein compressibility, with results validated by specialized radiology ultrasound. Cumulative sum (CUSUM) and the Bush and Mosteller models were used to analyze the learning curve, while generalized estimating equations were used to identify factors affecting diagnostic accuracy.

RESULTS

91 POCUS scans were conducted in 49 patients, resulting in 22% DVT confirmed by specialized venous ultrasound. In the CUSUM analysis, all four EM residents attained a 90% success rate at the common femoral vein, whereas only half achieved this rate when all three sites were considered. According to Bush and Mosteller models, 13-18 cases are required to attain 90-95% diagnostic accuracy. After 10-16 cases, the examination time for each resident decreased, and a 20% increase in examiner confidence was linked to a 2.506-fold increase in the DVT diagnosis accuracy.

CONCLUSION

EM residents generally required 13-18 cases for 90-95% DVT diagnostic accuracy, but proficiency varied among individuals, particularly requiring more cases for regions outside the common femoral vein.

Optimal D-Dimer Cutoff Values for Diagnosing Deep Vein Thrombosis in Patients with Comorbid Malignancies

BACKGROUND

Patients with malignancy are at high risk of venous thromboembolism, and early diagnosis is important. The Khorana score is known as a risk assessment for cancer-related thrombosis during chemotherapy, but there are still few reports on its diagnostic potential, the optimal D-dimer cutoff values for indications other than chemotherapy and the use of the Khorana score in combination with D-dimers. In this study, we examined the clinical appropriateness of increasing the D-dimer cutoff value.

METHODS

We retrospectively studied 208 malignancies out of 556 patients who underwent lower extremity venous ultrasonography at our hospital over a 2-year period from January 2018 to December 2019. The optimal D-dimer cutoff value for predicting deep vein thrombosis (DVT) in patients with malignancy was calculated by the Youden index. The usefulness of the Khorana score alone and the model combining the Khorana score with D-dimer for predicting DVT diagnosis was compared using receiver operating characteristic analysis.

RESULTS

Of 208 eligible patients, 59 (28.4%) had confirmed DVT. The optimal D-dimer cutoff value for predicting DVT comorbidity in patients with malignancy was 3.96 μg/mL. When the new D-dimer cutoff value was set at 4.0 μg/mL, the odds ratio (OR) for DVT diagnosis was 4.23 (95% confidence interval (CI) 2.10-8.55, P < 0.001), which was higher than the OR of 1.33 (95% CI: 0.98-1.81, P = 0.064) for the Khorana score. The area under the curve for the Khorana score and D-dimer was 0.714, which was significantly higher than the 0.611 for the Khorana score alone, with the difference being significantly higher at 0.103 (P = 0.004, 95% CI: 0.033-0.173).

CONCLUSIONS

The optimal D-dimer cutoff value for the diagnosis of DVT in patients with malignancy was 4.0 μg/mL. It was also suggested that the combination of the Khorana score with the D-dimer level was more accurate in diagnosing DVT than the Khorana score alone.

Evaluation of the diagnostic management of deep vein thrombosis in the emergency department of a tertiary hospital in Santa Catarina, Brazil: a cross-sectional study

Background

Venous thromboembolism is an entity that encompasses both deep vein thrombosis and pulmonary thromboembolism. Although protocols for the diagnosis of these diseases are well defined, there is evidence of inappropriate use of diagnostic resources.

Objectives

To define the epidemiological profiles of patients admitted to the emergency department with suspected deep vein thrombosis, to determine rates of inappropriate ordering of D-dimer assays and color venous Doppler echocardiography of the lower limbs, and to identify whether these requests followed the recommendations contained in the 2015 Brazilian Society of Angiology and Vascular Surgery guidelines.

Methods

We conducted a cross-sectional observational study that retrospectively evaluated 168 patients with suspected deep vein thrombosis for whom D-dimer assays were requested. The most common risk factors were measured and the pretest probability was calculated with the Wells score. The epidemiological profile of these patients and the rates of inappropriate D-dimer testing were assessed using descriptive statistics.

Results

The D-dimer requests were inadequate in 55 (32.7%) patients. Venous color Doppler ultrasound was used to examine the lower limbs of 14 (8.3%) of the patients with a low probability according to the Wells score and a negative D-dimer result. No additional diagnostic methods were used in 19 (11.3%) of those with a low probability according to the Wells score and a high D-dimer result. There was unnecessary use of CDUS in 35 (20.8%) cases. The overall rate of inappropriate workup was 53.5%.

Conclusions

Differences were found between clinical practice and the recommendations for diagnostic evaluation of patients with suspected deep vein thrombosis, with inappropriate use of diagnostic tests.

Conditional catheter-related thrombosis free probability and risk-adapted choices of catheter for lung cancer

Background

Current predictive tools assess catheter‐related thrombosis (CRT) in patients with lung cancer in a static manner at a single time point of catheterization. The subsequent hazard changes over time are unknown. The conditional catheter‐related thrombosis‐free probability (CCFP) can provide dynamic information on continual CRT‐free expectations. This study aimed to assess the CCFP and hazard rates based on risk categories and various venous access devices (VADs).

Methods

This retrospective study reviewed 939 patients with lung cancer with peripherally inserted central venous catheters (PICCs) or central venous catheters (CVCs) identified at the National Clinical Research Center for Cancer between January 1, 2015 and December 31, 2018. The incidence of CRT has also been reported. Patients were stratified into low‐ and high‐risk groups according to multivariate Cox regression analyses. CCFP is defined as the CRT‐free probability given that patients have no CRT for a definite time.

Results

A total of 507 patients with PICCs and 432 patients with CVCs were included in this study. The 3‐month CCFP increased from 74.2% at catheter insertion to 93.6% at 3 months. The hazards of CRT in the first month were highest (16.4%) and slightly thereafter. The high‐risk group initially had a higher (21.4%) but significantly decreased CRT hazard after 2 months (8.3%), whereas the low‐risk group maintained a comparable lower risk hazard of less than 5% after 1 month. In the overall cohort, patients with CVCs had lower CRT probability than those with PICCs (HR, 1.76; 95% CI: 1.28–2.41; p < 0.01). Further analysis demonstrated that compared with PICCs, CVCs provided a CRT‐free benefit in low‐risk patients (p = 0.02) but not in high‐risk patients (p = 0.06).

Conclusions

CCFP increased, and the hazards of CRT decreased over time in a risk‐dependent manner in patients with lung cancer. These valuable dynamic data may help optimize risk‐adjusted choices of VADs and risk‐adjusted prophylactic anticoagulation strategies for patients.

Deep thrombosis characterization using photoacoustic imaging with intravascular light delivery

Venous thromboembolism (VTE) is a condition in which blood clots form within the deep veins of the leg or pelvis to cause deep vein thrombosis. The optimal treatment of VTE is determined by thrombus properties such as the age, size, and chemical composition of the blood clots. The thrombus properties can be readily evaluated by using photoacoustic computed tomography (PACT), a hybrid imaging modality that combines the rich contrast of optical imaging and deep penetration of ultrasound imaging. With inherent sensitivity to endogenous chromophores such as hemoglobin, multispectral PACT can provide composition information and oxygenation level in the clots. However, conventional PACT of clots relies on external light illumination, which provides limited penetration depth due to strong optical scattering of intervening tissue. In our study, this depth limitation is overcome by using intravascular light delivery with a thin optical fiber. To demonstrate in vitro blood clot characterization, clots with different acuteness and oxygenation levels were placed underneath ten-centimeter-thick chicken breast tissue and imaged using multiple wavelengths. Acoustic frequency analysis was performed on the received PA channel signals, and oxygenation level was estimated using multispectral linear spectral unmixing. The results show that, with intravascular light delivery, clot oxygenation level can be accurately measured, and the clot age can thus be estimated. In addition, we found that retracted and unretracted clots had different acoustic frequency spectrum. While unretracted clots had stronger high frequency components, retracted clots had much higher low frequency components due to densely packed red blood cells. The PACT characterization of the clots was consistent with the histology results and mechanical tests.

Evaluation of the diagnostic management of deep vein thrombosis in the emergency department of a tertiary hospital in Santa Catarina, Brazil: a cross-sectional study

Abstract Background Venous thromboembolism is an entity that encompasses both deep vein thrombosis and pulmonary thromboembolism. Although protocols for the diagnosis of these diseases are well defined, there is evidence of inappropriate use of diagnostic resources. Objectives To define the epidemiological profiles of patients admitted to the emergency department with suspected deep vein thrombosis, to determine rates of inappropriate ordering of D-dimer assays and color venous Doppler echocardiography of the lower limbs, and to identify whether these requests followed the recommendations contained in the 2015 Brazilian Society of Angiology and Vascular Surgery guidelines. Methods We conducted a cross-sectional observational study that retrospectively evaluated 168 patients with suspected deep vein thrombosis for whom D-dimer assays were requested. The most common risk factors were measured and the pretest probability was calculated with the Wells score. The epidemiological profile of these patients and the rates of inappropriate D-dimer testing were assessed using descriptive statistics. Results The D-dimer requests were inadequate in 55 (32.7%) patients. Venous color Doppler ultrasound was used to examine the lower limbs of 14 (8.3%) of the patients with a low probability according to the Wells score and a negative D-dimer result. No additional diagnostic methods were used in 19 (11.3%) of those with a low probability according to the Wells score and a high D-dimer result. There was unnecessary use of CDUS in 35 (20.8%) cases. The overall rate of inappropriate workup was 53.5%. Conclusions Differences were found between clinical practice and the recommendations for diagnostic evaluation of patients with suspected deep vein thrombosis, with inappropriate use of diagnostic tests.

A Novel Tool for a Challenging Disease: Stasis Leg Ulcers Assessed Using QFlow in Triggered Angiography Noncontrast Enhanced Magnetic Resonance Imaging

Imaging characteristics of stasis leg ulcers (SLUs) are not easily demonstrated through existing diagnostic tools. Early diagnosis and treatment are crucial. This pilot study was conducted to assess the quantitative flow (QFlow) in triggered angiography noncontrast enhanced (TRANCE) magnetic resonance imaging (MRI) to identify the hemodynamics of victims with stasis leg ulcers (SLUs). This study included 33 patients with SLUs and 14 healthy controls (HC). The 33 patients with SLUs were divided into a reflux (15 patients) and a nonreflux group (18 patients). QFlow was done in the reflux, the nonreflux, and the HC. The stroke volume (SV), forward flow volume (FFV), absolute flow volume (AFV), mean flow (MF), and mean velocity (MV) were higher in the reflux than in the HC group in most segments, namely the external iliac vein (EIV), popliteal vein (PV), and great saphenous vein (GSV) (SV, p = 0.008; FFV, p = 0.008; absolute stroke volume (ASV), p = 0.008; MF, p = 0.002; MV, p = 0.009). No differences in the QFlow patterns were found in the GSV segment between the nonreflux group and the HC. Excellent performance in discriminating SLU with superficial venous reflux was reported for SV in the EIV and the PV (area under the curve (AUC) = 0.851 and 0.872), FFV in the EIV and PV (AUC = 0.854 and 0.869), ASV in the EIV and PV (AUC = 0.848 and 0.881), and MF in the EIV and PV (AUC = 0.866 and 0.868). The cutoff levels of SV/FFV/ASV/MF in the EIV/FV/PV/GSV for discriminating the SLU with superficial venous reflux were identified (p < 0.005). In conclusion, SLUs present different QFlow patterns by different etiology. The QFlow parameters of all vessel segments were higher in the morbid limbs of the reflux group than HC. The GSV segment of the nonreflux group displayed a pattern like the HC.

Occult deep vein thrombosis in lower limb trauma requiring microsurgical reconstruction-A retrospective cohort study

BACKGROUND

Delayed microsurgical reconstruction of lower extremity trauma is associated with increased risk of free flap loss, frequently following failure of the venous anastomosis. This has been attributed to thrombocytosis, but occult deep vein thrombosis (DVT) may contribute to this risk.

METHODS

We performed a retrospective cohort study of consecutive patients presenting to our service with lower limb injuries requiring microsurgical reconstruction between 2013 and 2017, and examined venous Duplex ultrasound reports, operation notes and free flap outcomes.

RESULTS

A total of 165 free flap reconstructions for lower limb trauma were performed for 162 limbs in 158 patients. Seventy-two limbs (44.4%) underwent preoperative venous Duplex ultrasound identifying occult DVT in 14 (19.4%) patients. Occult DVT was identified intraoperatively in a further 7 cases. Bilateral lower limb injuries (p = 0.0002), the level of injury at or above the knee (p < 0.0001), multiple levels of injury within the affected limb (p = 0.0008) and critical care admission (p = 0.0008) were significant risk factors for DVT. All 7 cases of DVT diagnosed intraoperatively prompted a change in the surgical plan for the recipient vein; however, preoperative identification of occult DVT also lead to an adjustment in the microsurgical plan in 4 out of 14 cases.

CONCLUSIONS

Prevalence of DVT is high in severe lower limb injury, potentially increasing the risk of free flap loss. Preoperative identification of occult DVT may influence the microsurgical plan and mitigate for this risk.

Stasis Leg Ulcers: Venous System Revises by Triggered Angiography Non-Contrast-Enhanced Sequence Magnetic Resonance Imaging

Objectives: The distribution of venous pathology in stasis leg ulcers is unclear. The main reason for this uncertainty is the lack of objective diagnostic tools. To fill this gap, we assessed the effectiveness of triggered angiography non-contrast-enhanced (TRANCE)-magnetic resonance imaging (MRI) in determining the venous status of patients with stasis leg ulcers. Methods: This prospective observational study included the data of 23 patients with stasis leg ulcers who underwent TRANCE-MRI between April 2017 and May 2020; the data were retrospectively analyzed. TRANCE MRI utilizes differences in vascular signal intensity during the cardiac cycle for subsequent image subtraction, providing not only a venogram but also an arteriogram without the use of contrast agents or radiation. Results: TRANCE MRI revealed that the stasis leg ulcers of nine of the 23 patients could be attributed to valvular insufficiency and venous occlusion (including deep venous thrombosis [DVT], May–Thurner syndrome, and other external compression). Moreover, TRANCE MRI demonstrated no venous pathology in five patients (21.7%). We analyzed TRANCE MRI hemodynamic parameters, namely stroke volume, forward flow volume, backward flow volume, regurgitant fraction, absolute volume, mean flux, stroke distance, and mean velocity, in the external iliac vein, femoral vein, popliteal vein, and great saphenous vein (GSV) in three of the patients with valvular insufficiency and three of those with venous occlusion. We found that the mean velocity and stroke volume in the GSV was higher than that in the popliteal vein in all patients with venous valvular insufficiency. Conclusions: Stasis leg ulcers may have no underlying venous disease and could be confirmed by TRANCE-MRI. TRANCE MRI has good Interrater reliability between Duplex study in greater saphenous venous insufficiency. It also potentially surpasses existing diagnostic modalities in terms of distinguishable hemodynamic figures. Accordingly, TRANCE-MRI is a safe and useful tool for examining stasis leg ulcers and is extensively applied currently.

Usefulness of computed tomography venography in gynecologic cancer patients with lower extremity edema

Lower extremity (LEx) edema is a common complication in gynecologic cancer patients. There are 2 main causes of edema in these patients such as deep vein thrombosis (DVT) and lymphedema. Early diagnosis and treatment of DVT are certainly important, but it is often difficult to evaluate proximal DVT by using ultrasound. The aim of this study is to demonstrate the usefulness of computed tomography venography of the lower extremity (CTV LEx) for the diagnosis of the DVT and investigate predictive factor of DVT in gynecologic cancer patients with LEx edema.The medical records of 415 gynecologic cancer patients who were referred to the department of rehabilitation medicine with LEx edema were retrospectively reviewed in this case-controlled study. We categorized CTV LEx findings as follows: DVT proximal to the inguinal ligament (inferior vena cava or iliac vein thrombosis) and DVT distal to the inguinal ligament (femoral, popliteal, or calf vein thrombosis). We also evaluated patient characteristics including D-dimer level. We analyzed the correlation of each factor with DVT frequency and used receiver operating characteristic curve analysis to determine the appropriate D-dimer threshold.Sixty-six patients were diagnosed with DVT; of them, 35 (53%) had DVT proximal to the inguinal ligament. Twenty-two patients were diagnosed with pulmonary embolism, of whom 15 had proximal DVT. Patients with proximal DVT tended to have pulmonary embolism (P < .001). Distal organ metastasis (odds ratio [OR], 2.88; P = .002) and a high D-dimer level (OR, 1.13; P = .001) were correlated with DVT.CTV LEx is a useful diagnostic tool for gynecologic cancer patients with LEx edema, particularly high-risk patients, that should be performed at the initial evaluation.

Correlation Between D-Dimer Level and Deep Venous Thrombosis in Patients With Acute Spinal Cord Injuries

Supplemental digital content is available in the text.

Objective

Venous thromboembolism is a serious life-threatening complication of S SCI. Measurement of D-dimer levels is used as a screening test for deep vein thrombosis. However, trauma, surgery, and motor weakness are known as factors that affect D-dimer levels. Thus, the aim of this study was to examine the correlation between D-dimer levels and deep vein thrombosis in relation to the comorbidities in acute spinal cord injury.

Design

A retrospective observational study was conducted at a hospital’s rehabilitation department. Forty-five patients without pharmacologic thromboembolic thromboprophylaxis 5−90 days after the onset of injury were enrolled.

Results

Fourteen patients (31%) were diagnosed with deep vein thrombosis using duplex ultrasonography. The mean ± SD D-dimer levels were 2.15 ± 2.74 and 6.98 ± 7.46 μg/ml in the deep vein thrombosis–negative and deep vein thrombosis–positive groups, respectively. The lower limb motor index scores significantly correlated with D-dimer levels regardless of the time between the onset of spinal cord injury and D-dimer testing. Patients with trauma had significantly increased D-dimer levels compared with patients without trauma.

Conclusion

Although D-dimer levels have limitations with regard to the positive prediction of acute spinal cord injury, it is a useful screening parameter for deep vein thrombosis. Trauma and lower limb motor weakness should be considered when analyzing D-dimer levels.

Novel Diagnostic Options without Contrast Media or Radiation: Triggered Angiography Non-Contrast-Enhanced Sequence Magnetic Resonance Imaging in Treating Different Leg Venous Diseases

OBJECTIVES

Venous diseases in the lower extremities long lacked an objective diagnostic tool prior to the advent of the triggered angiography non-contrast-enhanced (TRANCE) technique.

METHODS

An observational study with retrospective data analysis.

MATERIALS

Between April 2017 and June 2019, 66 patients were evaluated for venous diseases through TRANCE-magnetic resonance imaging (MRI) and were grouped according to whether they had occlusive venous (OV) disease, a static venous ulcer (SU), or symptomatic varicose veins (VV). The clinical appliance of TRANCE-MRI was analysed by groups.

RESULTS

In total, 63 patients completed the study. TRANCE-MRI could identify venous thrombosis, including that of the abdominal and pelvic vessels, and it enabled the timely treatment of underlying diseases in patients with OV disease. TRANCE-MRI was statistically compared with the duplex scan, the gold standard to exclude deep vein thrombosis (DVT) in the legs, with regard to their abilities to detect venous thrombosis by using Cohen's kappa coefficient at a compatible value of 0.711. It could provide the occlusion degree of the peripheral artery for treating an SU. Finally, TRANCE-MRI can be used to outline all collateral veins and occult thrombi before treating symptomatic or recurrent VV to ensure a perfect surgical plan and to avoid complications.

CONCLUSIONS

TRANCE-MRI is an innovative tool in the treatment of versatile venous pathology in the lower extremities and is widely used for vascular diseases in our institution.

Perioperative prevalence of deep vein thrombosis in patients with percutaneous kyphoplasty: A retrospective study with routine ultrasonography

In recent years, deep venous thrombosis (DVT) after spine surgery has received extensive attention, but perioperative prevalence of DVT in patients undergoing percutaneous kyphoplasty (PKP) is lacking.To assess the perioperative prevalence of deep vein thrombosis (DVT) in patients undergoing PKP with routinely applied ultrasonography.We reviewed 1113 consecutive patients undergoing PKP from January 2014 to August 2017. The surgical procedure was bilateral PKP. All patients were routinely examined with ultrasonography when admitted to the hospital and on the first post-operative day. Clinical signs of DVT were checked and recorded before examination.Forty (3.6%) out of 1113 patients were diagnosed with DVT by ultrasonography. Of the 40 detected cases of DVT, only six (0.54%) patients presented with clinical signs of DVT, demonstrating that there were 34 (3.05%) asymptomatic cases. No patient presenting with clinically suspected pulmonary embolism (PE) was observed. Gender, body mass index (BMI), operative time, hypertension, diabetes, heart disease, and lower limb fracture were not significant risk factors for DVT (P > .05). In contrast, patient age, oncologic conditions, DVT history, and paraplegia appeared to be significant risk factors for DVT (P < .01). There was no significant difference in the incidence of DVT found between the three PKP surgical levels (P > .05).The total incidence of perioperative DVT diagnosed with ultrasonography in patients undergoing PKP was 3.6%, of which only 0.54% was symptomatic cases. It is necessary to assess DVT using ultrasonography during the perioperative procedure of PKP, especially for high-risk patients.Level of evidence: Level IV.

Point-of-care ultrasound for deep venous thrombosis of the lower limb

The incidence and morbidity of deep venous thrombosis (DVT) and pulmonary embolus are high. Although efforts to increase screening for DVT have been recommended, this is limited by resources. Venous duplex ultrasound has replaced venography as the first-line investigation of choice for DVT, increasing availability and reducing patient exposure to radiation and intravenous contrast. Furthermore, an abbreviated ultrasound where DVT is inferred from incomplete venous compressibility has an equivalent accuracy to venous duplex, requiring less time and training enabling its widespread use by emergency, critical care and anaesthesia clinicians. In this review, the evolution and method of lower limb venous compression ultrasound is described along with evidence for its use in patients at high risk for DVT in these clinical settings.

Assessment of deep venous thrombosis in the lower extremity in Behçet's syndrome: MR venography versus Doppler ultrasonography

Lower extremity venous thrombosis (DVT) is the most common vascular manifestation of Behçet's syndrome (BS). Currently, Doppler ultrasonography (USG) is the most commonly preferred imaging modality in the diagnosis and follow-up of patients with acute and chronic DVT. Magnetic resonance (MR) venography, a quick and a non-invasive imaging modality, is successfully used to detect DVT in various settings. We had been unaware of studies with MR venography in BS. The aim of this study is to compare the diagnostic value of true fast imaging with steady-state precession magnetic resonance (True-FISP MR) venography and Doppler USG in the assessment of chronic DVT among patients with BS. 28 BS patients with chronic lower extremity DVT were studied. Common femoral (CFV) and femoral vein (FV) on both right and left sides were examined for the presence of thrombosis, recanalisation, collaterals and reflux. There are findings of chronic DVT in all Doppler USG images of 28 patients (45 of 56 FV and 35 of 56 CFV), while MR venography detects chronic thrombotic changes in 26/28 (93%) patients (43 of 52 FV and 28 of 52 CFV). Collateral veins are detected in 19 patients (19/28) with MR venography, whereas they are present in only 7 (7/28) with USG (P = 0.003). Furthermore, patients with severe post-thrombotic syndrome are more likely to have collateral formation on the MR compared to those without (12/14 vs 7/14; P = 0.043). Among patients with BS, MR venography might be an alternative or additional method to detect chronic thrombosis in the lower extremities.

High preoperative serum leptin level is an independent risk factor for deep vein thrombosis after total knee arthroplasty in osteoarthritis patients: A prospective and cross-sectional study

It suggests that a high leptin level may increase the risk of venous thromboembolism (VTE) in animal studies. However, clinical studies in this field are still largely unexplored. Our objective was to evaluate the relationship between the preoperative serum leptin levels and postoperative VTE incidence in osteoarthritis (OA) patients who underwent total knee arthroplasty (TKA) at our institute.We conducted a prospective and cross-sectional study in these OA patients from March 2014 to March 2016. Preoperative leptin levels were analyzed by Luminex assays. VTE was assessed preoperatively and on postoperative day 5 and 7. The potential risk factors for VTE were also documented.We enrolled 203 OA patients. No PE was detected and DVT was diagnosed in 34 patients postoperatively. There were significant differences between the median leptin levels in DVT group and non-DVT group [25.13 ng/mL (interquartile range, 14.51-44.31) vs 18.71 ng/mL (8.26-28.99), P = .007]. The relative risk of DVT significantly increased with natural logarithm (ln) leptin (per SD increase) (OR 2.37, 95% confidence interval (95% CI), 1.29-4.33, P = .005). Multivariate analyses adjusted for potential confounders showed ln leptin (per SD increase) was significantly associated with the relative risk of DVT (OR 2.17, 95% CI, 1.01-4.64, P = .046). When patients were subdivided into tertiles according to their leptin values, the OR for DVT increased with increasing tertiles of serum leptin (OR 1.03, 95% CI, 1.01-1.06, P for trend = .023).In the present study, our results indicate that a high preoperative leptin level may be an independent risk factor for postoperative DVT.

Accuracy of emergency physician–performed ultrasonography in the diagnosis of deep-vein thrombosis

Duplex ultrasound is the first-line diagnostic test for detecting lower limb deep-vein thrombosis (DVT) but it is time consuming, requires patient transport, and cannot be interpreted by most physicians. The accuracy of emergency physician–performed ultrasound (EPPU) for the diagnosis of DVT, when performed at the bedside, is unclear. We did a systematic review and meta-analysis of the literature, aiming to provide reliable data on the accuracy of EPPU in the diagnosis of DVT. The MEDLINE and EMBASE databases (up to August 2012) were systematically searched for studies evaluating the accuracy of EPPU compared to either colour-flow duplex ultrasound performed by a radiology department or vascular laboratory, or to angiography, in the diagnosis of DVT. Weighted mean sensitivity and specificity and associated 95% confidence intervals (CIs) were calculated using a bivariate random-effects regression approach. There were 16 studies included, with 2,379 patients. The pooled prevalence of DVT was 23.1% (498 in 2,379 patients), ranging from 7.4% to 47.3%. Using the bivariate approach, the weighted mean sensitivity of EPPU compared to the reference imaging test was 96.1% (95%CI 90.6–98.5%), and with a weighted mean specificity of 96.8% (95%CI:94.6–98.1%). Our findings suggest that EPPU may be useful in the management of patients with suspected DVT. Future prospective studies are warranted to confirm these findings.

Risk of deep venous thrombosis in elective neurosurgical procedures: a prospective, Doppler ultrasound-based study in children 12 years of age or younger

OBJECTIVE The risk of venous thromboembolism (VTE) from deep venous thrombosis (DVT) is significant in neurosurgical patients. VTE is considered a leading cause of preventable hospital deaths and preventing DVT is a closely monitored quality metric, often tied to accreditation, hospital ratings, and reimbursement. Adult protocols include prophylaxis with anticoagulant medications. Children's hospitals may adopt adult protocols, although the incidence of DVT and the risk or efficacy of treatment is not well defined. The incidence of DVT in children is likely less than in adults, although there is very little prospectively collected information. Most consider the risk of DVT to be extremely low in children 12 years of age or younger. However, this consideration is based on tradition and retrospective reviews of trauma databases. In this study, the authors prospectively evaluated pediatric patients undergoing a variety of elective neurosurgical procedures and performed Doppler ultrasound studies before and after surgery. METHODS A total of 100 patients were prospectively enrolled in this study. All of the patients were between the ages of 1 month and 12 years and were undergoing elective neurosurgical procedures. The 91 patients who completed the protocol received a bilateral lower-extremity Doppler ultrasound examination within 48 hours prior to surgery. Patients did not receive either medical or mechanical DVT prophylaxis during or after surgery. The ultrasound examination was repeated within 72 hours after surgery. An independent, board-certified radiologist evaluated all sonograms. We prospectively collected data, including potential risk factors, details of surgery, and details of the clinical course. All patients were followed clinically for at least 1 year. RESULTS There was no clinical or ultrasound evidence of DVT or VTE in any of the 91 patients. There was no clinical evidence of VTE in the 9 patients who did not complete the protocol. CONCLUSIONS In this prospective study, no DVTs were found in 91 patients evaluated by ultrasound and 9 patients followed clinically. While the study is underpowered to give a definitive incidence, the data suggest that the risk of DVT and VTE is very low in children undergoing elective neurosurgical procedures. Prophylactic protocols designed for adults may not apply to pediatric patients. Clinical trial registration no.: NCT02037607 (clinicaltrials.gov).

Venous haemodynamics of Jet Impulse Technology within a lower limb fibreglass cast: a randomized controlled trial

Objectives

We investigated popliteal venous haemodynamics of the VenaJet Jet Impulse Technology system within a below-knee fibreglass cast.

Design

Randomized controlled trial.

Participants

Twenty-four healthy participants aged 18–54 had both feet placed within the Jet Impulse Technology system and were randomised for one or other leg to be within a below-knee fibreglass cast.

Setting

Pacific Radiology, Lower Hutt, Wellington

Main outcome measures

The primary outcome variable was peak systolic velocity (cm/s) compared between legs with and without the cast at 60 min (after 10 min Jet Impulse Technology activation), using a mixed linear model and a non-inferiority bound of 4.8 cm/s. Secondary outcome variables were the difference in peak systolic velocity between the casted limb and the non-casted limb at baseline and 40 min after casting, and the difference in mean flow velocity (cm/s), vein diameter (mm), and total volume flow (L/min) between the casted limb and the non-casted limb at baseline, 40 and 60 min.

Results

The mean (standard deviation) peak systolic velocity was 4.6(1.5), 4.8(1.1), 28.8(16.1), and 4.3(1.2), 4.8(1.4) and 29.3(19.0) cm/s at baseline, 40 and 60 min in the casted and non-casted leg, respectively. The difference (95% confidence interval) between cast and no-cast at 60 min was −0.8 (−6.5 to 4.9) cm/s, P = 0.78. The peak systolic velocity, flow velocity and total volume flow at 40 min were not statistically significantly different from baseline for both casted and non-casted limb.

Conclusion

In healthy volunteers, the popliteal venous haemodynamics of the Jet Impulse Technology system was similar between the legs with and without a below-knee fibreglass cast. In-cast Jet Impulse Technology may provide a non-pharmacological option for venous thromboembolism prophylaxis for lower-limb cast-immobility.

Black-blood thrombus imaging (BTI): a contrast-free cardiovascular magnetic resonance approach for the diagnosis of non-acute deep vein thrombosis

BACKGROUND

Deep vein thrombosis (DVT) is a common but elusive illness that can result in long-term disability or death. Accurate detection of thrombosis and assessment of its size and distribution are critical for treatment decision-making. In the present study, we sought to develop and evaluate a cardiovascular magnetic resonance (CMR) black-blood thrombus imaging (BTI) technique, based on delay alternating with nutation for tailored excitation black-blood preparation and variable flip angle turbo-spin-echo readout, for the diagnosis of non-acute DVT. METHODS: This prospective study was approved by institutional review board and informed consent obtained from all subjects. BTI was first conducted in 11 healthy subjects for parameter optimization and then conducted in 18 non-acute DVT patients to evaluate its diagnostic performance. Two clinically used CMR techniques, contrast-enhanced CMR venography (CE-MRV) and three dimensional magnetization prepared rapid acquisition gradient echo (MPRAGE), were also conducted in all patients for comparison. All images obtained from patients were analyzed on a per-segment basis. Using the consensus diagnosis of CE-MRV as the reference, the sensitivity (SE), specificity (SP), positive and negative predictive values (PPV and NPV), and accuracy (ACC) of BTI and MPRAGE as well as their diagnostic agreement with CE-MRV were calculated. Besides, diagnostic confidence and interreader diagnostic agreement were evaluated for all three techniques.

RESULTS

BTI with optimized parameters effectively nulled the venous blood flow signal and allowed directly visualizing the thrombus within the black-blood lumen. Higher SE (90.4% vs 67.6%), SP (99.0% vs. 97.4%), PPV (95.4% vs. 85.6%), NPV (97.8% vs 92.9%) and ACC (97.4% vs. 91.8%) were obtained by BTI in comparison with MPRAGE. Good diagnostic confidence and excellent diagnostic and interreader agreements were achieved by BTI, which were superior to MPRAGE on detecting the chronic thrombus.

CONCLUSION

BTI allows direct visualization of non-acute DVT within the dark venous lumen and has the potential to be a reliable diagnostic tool without the use of contrast medium.

Deep venous thrombosis in patients with chronic spinal cord injury

CONTEXT/OBJECTIVE

Deep venous thrombosis (DVT) is a well-known complication of an acute spinal cord injury (SCI). However, the prevalence of DVT in patients with chronic SCI has only been reported in a limited number of studies. The aim of our study was to examine the prevalence of DVT in patients with SCI beyond three months after injury.

DESIGN

Cross-sectional study.

SETTING

Rehabilitation Department at the Bydgoszcz University Hospital in Poland.

PARTICIPANTS

Sixty-three patients with SCI that were more than 3 months post injury. The patients, ranging in age from 13 to 65 years, consisted of 15 women and 48 men; the mean age of the patients was 32.1 years. The time from injury varied from 4 to 124 months.

OUTCOME MEASURES

Clinical assessment, D-dimer and venous duplex scan.

RESULTS

The venous duplex scan revealed DVT in 5 of the 63 patients. The post-injury time in four of the patients varied between 4 and 5 months; one patient was 42 months post-injury.

CONCLUSION

DVT occurred in patients with chronic SCI, mainly by the 6th post injury month.

Inferior Vena Cava Filter-Related Thrombus/Deep Vein Thrombosis: Data and Management

Recurrent deep venous thrombosis and inferior vena cava (IVC) thrombosis are well-described complications following IVC filter placement. IVC thrombosis ranges in severity of clinical presentation, but can lead to significant morbidity and mortality with incidence rates depending on patient population and type of filter used. Endovascular therapies such as catheter-directed thrombolysis, mechanical thrombectomy, balloon venoplasty, and stenting are safe and effective in restoration of venous patency.

[Thrombosis of the subclavian vein after conservative treatment of a clavicular fracture: A rare complication]

We report the case of a 16-year-old male patient who presented with a clavicular fracture that was conservatively treated with a redressment bandage. After a few days the patient developed deep vein thrombosis of the subclavian, axillary and brachial veins, which was successfully treated with nadroparin. Conservative treatment of clavicular fractures is a common procedure in modern traumatology. Continuous, close monitoring and knowledge of rare but severe complications are necessary to avoid further complications.

Venous thromboembolism in cancer patients: an underestimated major health problem

Venous thromboembolism (VTE) is a major health problem among patients with cancer, its incidence in this particular population is widely increasing. Although VTE is associated with high rates of mortality and morbidity in cancer patients, its severity is still underestimated by many oncologists. Thromboprophylaxis of VTE now considered as a standard of care is still not prescribed in many institutions; the appropriate treatment of an established VTE is not yet well known by many physicians and nurses in the cancer field. Patients are also not well informed about VTE and its consequences. Many studies and meta-analyses have addressed this question so have many guidelines that dedicated a whole chapter to clarify and expose different treatment strategies adapted to this particular population. There is a general belief that the prevention and treatment of VTE cannot be optimized without a complete awareness by oncologists and patients. The aim of this article is to make VTE a more clear and understood subject.

Doppler US in rheumatic diseases with special emphasis on rheumatoid arthritis and spondyloarthritis

Developments in digital ultrasonography (US) technology and the use of high-frequency broadband transducers have increased the quality of US imaging, particularly of superficial tissues. Thus, US, particularly color US or power Doppler US, in which high-resolution transducers are used, has become an important imaging modality in the assessment of rheumatic diseases. Furthermore, therapeutic interventions and biopsies can be performed under US guidance during the assessment of lesions. In this era of effective treatments, such as biologics, improvements in synovial inflammation in rheumatoid arthritis as well as changes in enthesitis in spondyloarthropathies, including ankylosing spondylitis and psoriatic arthritis, can be monitored effectively using gray-scale and/or power Doppler US. US is also a good imaging modality for crystal arthropathies, including gout and pseudogout, in which synovitis, erosions, tophi, and crystal deposition within or around the joint can be visualized readily. Vascular and tenosynovial structures, as well as the salivary glands, can be assessed with US in vasculitis and connective tissue disorders, including systemic lupus erythematosus and Sjögren's syndrome. Current research is focused on improving the sensitivity, specificity, validity, and reproducibility of US findings. In this review, we summarized the role of US, particularly power Doppler US, in rheumatic diseases and inflammation in superficial tissues.

The JAK2 V617F mutational status and allele burden may be related with the risk of venous thromboembolic events in patients with Philadelphia-negative myeloproliferative neoplasms

INTRODUCTION

Patients with Philadelphia-negative myeloproliferative neoplasms (Ph(-) MPNs) are at increased risk of thromboembolic and hemorrhagic complications. The aim of the study was to determine the relationship between JAK2 V617F mutational status, JAK2 V617F allele burden and the risk of vascular complications occurrence.

MATERIALS AND METHODS

Analysis was performed in a cohort of 186 patients diagnosed with polycythemia vera (53), essential thrombocythemia (114), primary myelofibrosis (11), and unclassified MPN (8). The risk of vascular complications development was analyzed in 126 JAK2 V617F-positive patients with respect to allele burden assessed with allele-specific 'real-time' quantitative polymerase chain reaction (AS RQ-PCR).

RESULTS

Overall prevalence of any vascular complications was 44.6%. Arterial thrombosis occurred in 20.4%, venous thromboembolism (VTE) in 11.3%, bleeding episodes in 24.7% of patients. Individuals harboring JAK2 V617F mutation, regardless of MPN type, were at higher risk of VTE (OR=5.15, 95%CI: 1.16-22.90, P=0.024), mainly deep vein thrombosis (DVT). JAK2 allele burden higher than 20% identified patients with 7.4-fold increased risk of VTE (95%CI: 1.6-33.7, P=0.004), but not of arterial thrombosis, neither of bleeding complications, and remained the only significant VTE risk factor in multivariate logistic regression. High allele burdens (over 50%) were strikingly associated with proximal DVT cases, but not with distal DVT.

CONCLUSIONS

The group of MPN patients with JAK2 V617F allele burden higher than 20% may benefit the most from vigilant monitoring and appropriate prophylaxis against vascular events. Inclusion of JAK2 V617F mutant allele burden in new risk stratifications seems to be justified and requires controlled prospective trials.

Efficacy of micromobile foot compression device in increasing lower limb venous blood flow

Background. A novel, micromobile foot compression device (MMC) has been developed to reduce the risk of venous thromboembolism associated with prolonged seated immobility. Objective. To compare the efficacy of the MMC with graduated compression stockings in augmenting lower limb venous blood flow. Patients/Methods. Twenty participants were randomised to wear the MMC or a graduated compression stocking (GCS) on either the left or right leg while seated. Doppler ultrasound measurements of popliteal vein blood flow and leg circumference measurements were made -30 and -10 minutes (baseline) and +30 and +60 minutes following application of the interventions. The primary outcome variable was peak systolic velocity. A mixed linear model was used, with covariates including baseline measurement, randomised side, time, and a time by interaction term. Results. The mean popliteal vein peak systolic velocity at 60 minutes with the MMC was 20.1 cm/s which was significantly higher than with the GCS (difference 14.1 cm/s 95% CI 12.1-16.2), representing a 3.8-fold increase from baseline. Conclusion. The MMC resulted in a marked increase in lower limb venous blood flow which suggests that it may have efficacy in reducing the risk of venous thromboembolism associated with prolonged seated immobility, such as long distance air travel.

A prospective study on the incidence of postoperative venous thromboembolism in Korean gastric cancer patients: an inquiry into the application of Western guidelines to Asian cancer patients

Several Western guidelines recommend the routine use of pharmacologic thromboprophylaxis for cancer surgery patients to prevent venous thromboembolism (VTE). However, the necessity of routine pharmacologic perioperative thromboprophylaxis in Asian gastric cancer (GC) patients has not been clearly determined. To determine the necessity of routine perioperative pharmacologic thromboprophylaxis in Korean gastric cancer patients, the incidence of postoperative VTE was prospectively evaluated in gastric cancer patients receiving surgery. Among 610 GC patients who had received surgery, 375 patents underwent routine duplex Doppler ultrasonography (DUS) on days 5–12 following surgery to detect VTE and then VTE-related symptoms and signs were checked at 4 weeks after surgery (cohort A). The 235 patients that declined DUS were registered to cohort B and the occurrence of postoperative VTE was retrospectively analyzed. In cohort A, symptomatic or asymptomatic VTE until 4 weeks after surgery was detected in 9 patients [2.4%; 95% confidence interval (CI); 0.9–3.9]. Tumor stage was a significant factor related to VTE development [stage I, 1.4%; stage II/III, 2.4%; stage IV, 9.7% (P = 0.008)]. In multivariate analysis, patients with stage IV had a higher postoperative VTE development [odds ratio, 8.18 (95% CI, 1.54–43.42)] than those with stage I. In cohort B, a low incidence of postoperative VTE was reaffirmed; only one postoperative VTE case (0.4%) was observed. In conclusion, the incidence of postoperative VTE in Korean GC patients was only 2.4%. Risk-stratified applications of perioperative pharmacologic thromboprophylaxis are thought to be more appropriate than the routine pharmacologic thromboprophylaxis in Korean GC patients receiving surgery.

Subclavian vein thrombosis after application of body cast

Mehta-Cotrel body casting is a well-recognized and effective technique for the treatment of progressive infantile scoliosis. The treatment can be challenging to execute given the commitment required by the patient's family and treatment team, and is not without complications. In this report, we detail the occurrence of a subclavian vein thrombosis after the placement of a Mehta-Cotrel cast for the treatment of progressive infantile kyphoscoliosis. To date, this is a previously unreported complication after body casting. Expeditious and accurate diagnosis of this complication leads to effective treatment without further morbidity. Therefore, clinicians using body casting for the treatment of scoliosis should be aware of the possibility of this complication and know how to quickly diagnose and treat it.

Controvérsias no diagnóstico e tratamento da trombose venosa profunda pela ecografia vascular

A trombose venosa profunda é uma entidade clínica potencialmente grave, responsável por elevada morbimortalidade. A ecografia vascular representa o método propedêutico de escolha no diagnóstico e acompanhamento dos pacientes com essa doença. Entretanto, várias questões permanecem controversas, tais como a abordagem inicial do paciente com suspeita de trombose venosa profunda, os tipos de protocolo a serem usados, o tempo para a realização do exame e a trombose no plexo de panturrilha. O objetivo dessa revisão é discutir esses assuntos à luz dos conhecimentos atuais.

Diagnostic approach to deep venous thrombosis and pulmonary embolism in the critical care setting

Considerable progress has been made during the last 30 years in the prevention, diagnosis, and therapy of venous thromboembolism. This article discusses the epidemiology, pathophysiology, and clinical presentation of the disease as well as the diagnostic uncertainty that exists in the critical care setting. Diagnostic approaches for deep venous thrombosis and pulmonary embolism are considered, including clinical prediction rules, D-dimer, contrast venography, duplex ultrasonography, computed tomographic angiography and venography, magnetic resonance imaging, ventilation–perfusion scanning, chest radiograph, arterial blood gases, electrocardiography, and echocardiography.

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.

Merino wool graduated compression stocking increases lower limb venous blood flow: a randomized controlled trial

INTRODUCTION

Graduated compression stockings represent a nonpharmacological approach to reduce the risk of deep vein thrombosis (DVT) and pulmonary embolism (PE) due to prolonged immobility through reducing lower limb venous stasis. A novel merino wool, double-layer, below-knee graduated compression stocking has been developed to reduce the risk of air travel-related DVT and PE.

METHODS

Twenty healthy adult participants were randomized to wear the novel graduated compression stocking on either the left or right leg. Doppler ultrasound measurements of popliteal venous blood flow were made on both legs over a 120-minute period. The primary outcome was peak systolic velocity in the popliteal vein at 120 minutes. Secondary outcomes included mean flow velocity, total volume flow, vein cross-sectional area, and change in ankle and calf measurements.

RESULTS

The popliteal vein peak systolic velocity was 0.35 cm/s (95% confidence intervals [CI], 0.22 to 0.49, P<0.001) higher with stocking use at 120 minutes, a difference of 24%. Mean flow velocity and total volume flow were also significantly higher with stocking use. Ankle and calf circumference were decreased with stocking use, with an overall difference of -6.3 mm (95% CI, -11.3 to -1.2, P=0.021) and -7.9 mm (95% CI, -13.3 to -2.4, P=0.011), respectively.

CONCLUSION

The novel merino wool double-layer, below-knee graduated compression stocking increases lower limb venous blood flow during prolonged seated immobility. Its use is likely to reduce the risk of DVT and PE in situations of prolonged seated immobility, such as long-distance air travel. The reduction in lower limb swelling associated with their use suggests that the stockings are likely to have utility in the treatment of chronic venous insufficiency and lymphedema.

Cost-effectiveness of strategies for diagnosing pulmonary embolism among emergency department patients presenting with undifferentiated symptoms

STUDY OBJECTIVE

Symptoms associated with pulmonary embolism can be nonspecific and similar to many competing diagnoses, leading to excessive costly testing and treatment, as well as missed diagnoses. Objective studies are essential for diagnosis. This study evaluates the cost-effectiveness of different diagnostic strategies in an emergency department (ED) for patients presenting with undifferentiated symptoms suggestive of pulmonary embolism.

METHODS

Using a probabilistic decision model, we evaluated the incremental costs and effectiveness (quality-adjusted life-years gained) of 60 testing strategies for 5 patient pretest categories (distinguished by Wells score [high, moderate, or low] and whether deep venous thrombosis is clinically suspected). We performed deterministic and probabilistic sensitivity analyses.

RESULTS

In the base case, for all patient pretest categories, the most cost-effective diagnostic strategy is to use an initial enzyme-linked immunosorbent assay D-dimer test, followed by compression ultrasonography of the lower extremities if the D-dimer is above a specified cutoff. The level of the preferred cutoff varies with the Wells pretest category and whether a deep venous thrombosis is clinically suspected. D-dimer cutoffs higher than the current recommended cutoff were often preferred for patients with even moderate and high Wells categories. Compression ultrasonography accuracy had to decrease below commonly cited levels in the literature before it was not part of a preferred strategy.

CONCLUSION

When pulmonary embolism is suspected in the ED, use of an enzyme-linked immunosorbent assay D-dimer assay, often at cutoffs higher than those currently in use (for patients in whom deep venous thrombosis is not clinically suspected), followed by compression ultrasonography as appropriate, can reduce costs and improve outcomes.

Identifying and avoiding bias in research

This narrative review provides an overview on the topic of bias as part of a series of articles in Plastic and Reconstructive Surgery on evidence-based medicine. Bias can occur in the planning, data collection, analysis, and publication phases of research. Understanding research bias allows readers to critically and independently review the scientific literature and avoid treatments that are suboptimal or potentially harmful. A thorough understanding of bias and how it affects study results is essential for the practice of evidence-based medicine.

Asymptomatic deep vein thrombosis in advanced cancer patients: the value of venous sonography

PURPOSE

Although guidelines for venous thromboembolism prevention are available, the implementation of anticoagulant prophylaxis in patients with advanced cancer has yet to be more clearly defined. We aim to determine the incidence of lower extremity deep vein thrombosis (DVT) diagnosed by Doppler sonography (USD) in asymptomatic nonambulatory patients with advanced cancer.

METHOD

In a prospective study, 44 nonambulatory cancer patients with grade 3-4 World Health Organization performance status, asymptomatic for lower extremity DVT, underwent bilateral venous USD studies of the lower extremities. Different risk factors and laboratory data were registered and correlated with the incidence of DVT.

RESULT

Asymptomatic DVT was detected in 15 of 44 patients (34%, 95% CI, 0.21-0.49). Twenty-three percent of all patients had isolated deep calf vein thrombi and 11% of all patients had thrombi in the proximal veins. The only significant risk factor was the number of metastatic sites. DVT was found in 4 of 23 (17.4%) patients with one metastatic site as opposed to 11 of 21 (52.3%) with two or more sites (p < 0.01).

CONCLUSION

USD of the lower extremities detected asymptomatic DVT in 34% of advanced nonambulatory cancer patients and may serve as an additional decision-making tool in the consideration of anticoagulant therapy for this specific population.

Utility of balanced steady-state free precession MR venography in the diagnosis of lower extremity deep venous thrombosis

OBJECTIVE

The purpose of this study was to determine the sensitivity and specificity of balanced steady-state free precession MR venography in the diagnosis of lower extremity deep venous thrombosis.

SUBJECTS AND METHODS

After undergoing lower extremity ultrasound because of suspicion of deep venous thrombosis, 64 patients were prospectively recruited to undergo balanced steady-state free precession MR venography with ultrasound as the reference standard. Ultrasound images were independently interpreted by two blinded ultrasound radiologists, and MR venograms were independently interpreted by two blinded MRI radiologists. The sensitivity, specificity, positive predictive value, and negative predictive value of MR venography were calculated for the diagnoses of all deep venous thrombosis, acute thrombi, and thrombosis of the popliteal, femoral, and common femoral veins individually. Proximal extent, thrombus age, ancillary findings, and interobserver agreement calculated with the Cohen kappa test were evaluated for ultrasound and MRI. The McNemar test was used to evaluate for statistical differences in diagnostic accuracy.

RESULTS

MR venography had a sensitivity of 94.7%, specificity of 100%, positive predictive value of 100%, and negative predictive value of 97.7% for the diagnosis of all thrombi. For acute thrombi, the MR venography and ultrasound results were completely concordant. MR venography depicted greater proximal extent in five of 18 cases in which thrombosis was found. The MR venographic findings agreed completely with the ultrasound findings in determination of thrombus age. For both ultrasound and MR venography, interobserver agreement was 100% on a per-patient basis. No statistical difference was identified in the diagnostic performance of the two techniques.

CONCLUSION

Balanced steady-state free precession MR venography is highly accurate in the diagnosis of lower extremity deep venous thrombosis.

Clinical Outcomes Using Modest Intravascular Hypothermia After Acute Cervical Spinal Cord Injury

BACKGROUND

Although a number of neuroprotective strategies have been tested after spinal cord injury (SCI), no treatments have been established as a standard of care.

OBJECTIVE

We report the clinical outcomes at 1-year median follow-up, using endovascular hypothermia after SCI and a detailed analysis of the complications.

METHODS

We performed a retrospective analysis of American Spinal Injury Association and International Medical Society of Paraplegia Impairment Scale (AIS) scores and complications in 14 patients with SCI presenting with a complete cervical SCI (AIS A). All patients were treated with 48 hours of modest (33°C) intravascular hypothermia. The comparison group was composed of 14 age- and injury-matched subjects treated at the same institution.

RESULTS

Six of the 14 cooled patients (42.8%) were incomplete at final follow-up (50.2 [9.7] weeks). Three patients improved to AIS B, 2 patients improved to AIS C, and 1 patient improved to AIS D. Complications were predominantly respiratory and infectious in nature. However, in the control group, a similar number of complications was observed. Adverse events such as coagulopathy, deep venous thrombosis, and pulmonary embolism were not seen in the patients undergoing hypothermia.

CONCLUSION

This study is the first phase 1 clinical trial on the safety and outcome with the use of endovascular hypothermia in the treatment of acute cervical SCI. In this small cohort of patients with SCI, complication rates were similar to those of normothermic patients with an associated AIS A conversion rate of 42.8%.