Below-knee deep vein thrombosis (DVT): diagnostic and treatment patterns

Histotripsy and Catheter-Directed Lytic: Efficacy in Highly Retracted Porcine Clots In Vitro

OBJECTIVE

Standard treatment for deep vein thrombosis (DVT) involves catheter-directed anticoagulants or thrombolytics, but the chronic thrombi present in many DVT cases are often resistant to this therapy. Histotripsy has been found to be a promising adjuvant treatment, using the mechanical action of cavitating bubble clouds to enhance thrombolytic activity. The objective of this study was to determine if histotripsy enhanced recombinant tissue plasminogen activator (rt-PA) thrombolysis in highly retracted porcine clots in vitro in a flow model of occlusive DVT.

METHODS

Highly retracted porcine whole blood clots were treated for 1 h with either catheter-directed saline (negative control), rt-PA (lytic control), histotripsy, DEFINITY and histotripsy or the combination of rt-PA and histotripsy with or without DEFINITY. Five-cycle, 1.5 MHz histotripsy pulses with a peak negative pressure of 33.2 MPa and pulse repetition frequency of 40 Hz were applied along the clot. B-Mode and passive cavitation images were acquired during histotripsy insonation to monitor bubble activity.

RESULTS

Clots subjected to histotripsy with and without rt-PA exhibited greater thrombolytic efficacy than controls (7.0% flow recovery or lower), and histotripsy with rt-PA was more efficacious than histotripsy with saline (86.1 ± 10.2% compared with 61.7 ± 19.8% flow recovery). The addition of DEFINITY to histotripsy with or without rt-PA did not enhance either thrombolytic efficacy or cavitation dose. Cavitation dose generally did not correlate with thrombolytic efficacy.

CONCLUSION

Enhancement of thrombolytic efficacy was achieved using histotripsy, with and without catheter-directed rt-PA, in the presence of physiologic flow. This suggests these treatments may be effective as therapy for DVT.

Comparison of clinical outcomes among patients with isolated axial vs muscular calf vein thrombosis: A systematic review and meta-analysis

OBJECTIVE

Thrombi in the axial calf veins have quite different anatomical and physiological characteristics from that in the muscular calf veins, but their treatment was usually addressed in the same manner. We performed a meta-analysis of randomized and cohort studies to compare clinical outcomes among patients with isolated axial vs muscular calf deep vein thrombosis (DVT).

METHODS

Recurrent venous thromboembolism (VTE) was selected as the primary outcome. Resolution, proximal propagation of calf DVT, pulmonary embolism (PE), major bleeds, and clinically relevant non-major bleeds were separately analyzed as secondary outcomes. Data were pooled and compared with risk ratio (RR) and 95% confidence interval (CI).

RESULTS

Thirteen studies, consisting of 4889 patients, met the inclusion criteria and were included for analysis. A greater rate of recurrent VTE (FE model: RR, 1.23; 95% CI, 1.00-1.53; I2 = 29%), resolution (FE model: RR, 1.32; 95% CI, 1.01-1.72; I2 = 31%), proximal propagation (FE model: RR, 1.63; 95% CI, 1.10-2.41; I2 = 40%), and PE (FE model: RR, 2.79; 95% CI, 1.31-5.95; I2 = 0%) in the axial group compared with the muscular group. There was no difference in the pooled estimates for major bleeds (FE model: RR, 1.09; 95% CI, 0.61-1.95; I2 = 0%), and clinically relevant non-major bleeds (FE model: RR, 1.80; 95% CI, 0.93-3.48) in the axial and muscular arms.

CONCLUSIONS

Patients with calf DVT limited to muscular veins might have a lower rate of recurrent VTE, resolution, proximal propagation, and PE vs those with axial calf vein involvement and exhibited similar safety outcomes.

Nomogram for predicting pulmonary embolism in gynecologic inpatients with isolated distal deep venous thrombosis

OBJECTIVE

To investigate the incidence of isolated distal deep venous thrombosis (IDDVT) concurrent with pulmonary embolism (PE) in gynecologic inpatients, analyze the risk factors for IDDVT with PE, and establish a nomogram model for IDDVT patients with PE.

METHODS

A total of 260 patients were diagnosed with IDDVT between December 2017 and November 2020. The incidence of PE in these patients was determined using computed tomography pulmonary angiography. Logistic regression analysis was used to identify the related risk factors. On this basis, nomogram risk prediction models were established.

RESULTS

Among 260 patients with IDDVT, 106 (40.8%) had concurrent PE, of whom 74 (28.5%) experienced silent PE. Univariate logistic analysis demonstrated statistical significance for body mass index (BMI; P = 0.044), glucocorticoid therapy (P = 0.009), hypertension (P < 0.001), and diabetes (P < 0.001). Multivariate logistic analysis revealed that these were independent risk factors for IDDVT with PE that retained statistical significance. A nomogram based on these factors was constructed to predict PE in patients with IDDVT. Its receiver operating characteristic (ROC) showed an area under the curve of 0.710 (95% confidence interval 0.642-0.779), with prediction sensitivity of 64.2% and prediction specificity of 76.6%.

CONCLUSIONS

In the present study, a high prevalence of PE was found in gynecologic inpatients with IDDVT. Glucocorticoid therapy, hypertension, diabetes, and BMI were independent risk factors for IDDVT patients with PE. Taking these risk factors into account, a nomogram risk prediction model was developed to help facilitate early detection of concurrent PE.

Efficacy and safety of sonographer discretion to terminate a venous duplex ultrasound for diagnosis of deep vein thrombosis in coronavirus disease 2019 patients

OBJECTIVE

Sonographers performing venous duplex ultrasound (VDUS) of patients with coronavirus disease 2019 (COVID-19) have an increased risk of exposure owing to their close contact with these patients for an extended period. The objective of the present study was to evaluate the efficacy of a modified COVID-19 VDUS protocol to reduce sonographer exposure to COVID-19 patients.

METHODS

We performed a single-center retrospective review. Patients who had undergone VDUS under the modified COVID-19 protocol between March 1, 2020, and June 30, 2020, with a confirmed or presumed COVID-19 diagnosis at the VDUS were included. The modified COVID-19 protocol was defined as the ability of the sonographer to terminate the examination on detection of an acute deep vein thrombosis (DVT). The primary outcome measures were the number of anatomic deep venous segments recorded by the sonographer, which was used as a surrogate measure for sonographer exposure time, and the number of acute DVTs found on follow-up examinations in segments not visualized at the index VDUS.

RESULTS

A total of 160 lower extremity VDUS (LEVDUS) scans and 72 upper extremity VDUS (UEVDUS) scans were performed using the modified COVID-19 protocol. The index VDUS had found an acute DVT for 44 of 160 patients (27.5%) who had undergone LEVDUS and 26 of 72 (36.6%) who had undergone UEVDUS. On follow-up imaging, 7 of 38 LEVDUS scans (17.9%) and 1 of 10 UEVDUS scans (10%) had demonstrated a new acute DVT. Malignancy and surgery 30 days before imaging were significantly associated with acute lower extremity DVT, and mechanical ventilation and extracorporeal membrane oxygenation were associated with acute upper extremity DVT. On the index VDUS, the average was 10.6 of 12 total visualized segments on LEVDUS and 6.4 of 10 total segments on UEVDUS. Of the index VDUS scans, 35.6% of the LEVDUS and 78.6% of the UEVDUS scans had been abbreviated. The index VDUS scans that were positive for acute DVT had had significantly fewer visualized segments for both lower (8.4 vs 11.5; P < .0001) and upper (4.2 vs 7.6) extremities (P < .0001). On the follow-up examinations, only one of eight new acute DVTs had been found in a patient whose index VDUS had been abbreviated and the corresponding segment not assessed. These findings did not affect the patient's clinical course.

CONCLUSIONS

The modified COVID-19 VDUS protocol reduced sonographers' potential exposure time to COVID-19. Additionally, the clinical efficacy was maintained, with no missed DVTs, despite the abbreviation of the VDUS examinations.

'Current trends in lower limb Doppler scanning in Ireland'

INTRODUCTION

The clinical need to diagnose and treat above knee deep vein thrombosis (AKDVT) has long been established in literature and in practice. On the other hand, the need to diagnose and treat below knee deep vein thrombosis (BKDVT) continues to be debated in literature. This has resulted in variation in clinical guidelines and protocols nationwide. This research aims to establish if there is a standard practice in Irish ultrasound departments and if so, what that practice is and where sonographers are getting information to inform this.

METHODS

A questionnaire was designed using SurveyMonkey and distributed using online platforms. The questionnaire aimed to establish the experience of the sonographer, the types of exams performed, protocols/guidelines used as well as scenarios where the sonographer might deviate from protocol.

RESULTS

The study yielded 90 responses. The research found 49% of sites perform whole leg ultrasound routinely and 46% perform proximal ultrasound only. 41% of respondents said their protocols were based on clinical guidelines however, 22% of participants didn't know what these guidelines were. 49% of respondents were unaware of what treatment a patient would receive in cases where there is a high clinical suspicion of DVT, but the ultrasound is negative for DVT.

CONCLUSION

The research has established a lack of consistency amongst sonographers and scanning practices with a fairly even split (49% of respondents perform whole leg ultrasound and 46% perform proximal only). Not only has the research identified a lack of standardised scanning approach nationwide, but inconsistencies are also seen in the guidelines that inform our department's protocols as well as inconspicuous terms used in radiology reporting and jargon in literature in relation to DVT.

IMPLICATIONS FOR PRACTICE

1. An inconsistency in practice has been established. Discussions are now needed to decide what guidelines should be implemented into Irish Ultrasound DVT protocols. 2. A national protocol for BKDVT would result in all patients in Ireland having access to the same standard of care. 3. Call for consensus on appropriate training for sonographers undertaking LLDs.

Clinical presentation of isolated calf deep vein thrombosis in inpatients and prevalence of associated pulmonary embolism

OBJECTIVE

There is a controversy over the clinical significance and optimal treatment for isolated calf DVT. This study aimed to investigate the clinical presentation of isolated calf deep vein thrombosis (DVT) and the association of isolated calf DVT with pulmonary embolism (PE) in inpatients.

METHODS

A total of 1435 hospitalized patients underwent whole-leg duplex ultrasound between January 2018 and June 2020. Among them, 135 were diagnosed with isolated calf vein DVT.

RESULTS

The soleal vein was the most frequently involved (52.6%). Thrombus was detected only in axial veins in 57 patients (42.2%), muscular veins in 46 patients (34.4%), and in both axial and muscular veins in 32 patients (23.7%). Of the 135 patients, 44 patients (32.6%) had underwent recent orthopedic surgery, 31 patients (23.0%) had active cancer, and 22 patients (16.3%) had a history of recent stroke. The reasons for duplex ultrasound were leg edema and/or pain in 57 patients (42.2%), diagnosis of PE in 33 (24.4%), and elevated D-dimer level in 27 patients (20.0%). Sixteen patients (11.9%) were diagnosed as incidental findings on imaging studies for other purposes. Ninety-six patients (71.1%) received anticoagulation therapy. Concurrent PE was diagnosed in 45 patients (33.3%) and 14 patients had lesions in the main pulmonary artery. Among 45 patients with concurrent PE, 35 patients were diagnosed without leg edema and/or pain. Recurrent VTE was observed in four patients (3.0%) with a mean follow-up of 15.5±12.7 months.

CONCLUSIONS

Isolated calf DVT was associated with a high prevalence of PE in hospitalized patients. Patients with isolated calf DVT even without leg edema and/or pain may have concurrent PE. Anticoagulation therapy should be considered for isolated calf DVT in inpatients. The muscular veins were frequently involved, thus should be thoroughly evaluated and imaged.

Is routine screening for silent pulmonary embolism justified in patients with deep vein thrombosis?

The incidence of asymptomatic pulmonary embolism (PE) exceeds 70% in patients with deep venous thrombosis (DVT), even in cases of distal deep vein thrombosis. We report the case of a patient with a diagnosis of DVT in the lower left limb associated with asymptomatic PE who presented late symptoms due to this same PE. The absence of acute symptoms and the late onset of symptoms could have provoked doubts about the most appropriate treatment, resulting in unnecessary interventions, if pulmonary embolism had not already been diagnosed with tomography. In the present case, we demonstrate that computed tomography angiography conducted at the time of DVT diagnosis accurately diagnosed PE and prevented any misinterpretation of recurrent DVT in a patient already being medicated, which could have been mistakenly interpreted as demonstrating failure of anticoagulant therapy. Such a situation could lead to unnecessary intervention to fit an inferior vena cava filter. We cannot suggest that a classic medical conduct should be reformulated simply on the basis of a case report. However, we would be remiss not to suggest that well-designed studies should be carried out in the future to assess the need for this examination in the acute phase.

Natural History of Isolated Below-Knee Vein Thrombosis in Patients with Spinal Cord Injury

In the general population, serial imaging is recommended over anticoagulant therapy for below-knee deep vein thrombosis (BKDVT). However, no clinical trial in Asian patients with spinal cord injury and BKDVT has been performed. Therefore, we evaluated the natural course of BKDVT in patients with acute spinal cord injury. We retrospectively analyzed inpatients with spinal cord injury with BKDVT between 2016 and 2020. All patients underwent inpatient rehabilitation treatment and duplex ultrasonographic examination of both the lower extremities at follow-up. After screening 172 patients with acute spinal cord injury for deep vein thrombosis using duplex ultrasound, 27 patients with below-the-knee deep vein thrombosis were included in this study. The mean lower-extremity motor score (median, interquartile range) was 66.0, 54.0–74.5. Sixteen patients received a non-vitamin K antagonist oral anticoagulant (NOAC) for anticoagulation. None of the patients had proximal propagation according to the follow-up duplex ultrasonography. BKDVT disappearance was not significantly different between the NOAC treatment and non-treatment groups. Asian patients with spinal cord injury have a low incidence of venous thromboembolism and favorable natural history of BKDVT. We recommend serial imaging over anticoagulant therapy for BKDVT in these patients.

2021 John N. Insall Award: Aspirin is effective in preventing propagation of infrapopliteal deep venous thrombosis following total knee arthroplasty

AIMS

The optimal management of an infrapopliteal deep venous thrombosis (IDVT) following total knee arthroplasty (TKA) remains unknown. The risk of DVT propagation and symptom progression must be balanced against potential haemorrhagic complications associated with administration of anticoagulation therapy. The current study reports on a cohort of patients diagnosed with IDVT following TKA who were treated with aspirin, followed closely for development of symptoms, and scanned with ultrasound to determine resolution of IDVT.

METHODS

Among a cohort of 5,078 patients undergoing TKA, 532 patients (695 TKAs, 12.6%) developed an IDVT between 1 January 2014 to 31 December 2019 at a single institution, as diagnosed using Doppler ultrasound at the first postoperative visit. Of the entire cohort of 532 patients with IDVT, 91.4% (486/532) were treated with aspirin (325 mg twice daily) and followed closely. Repeat lower limb ultrasound was performed four weeks later to evaluate the status of IDVT.

RESULTS

Follow-up Doppler ultrasound was performed on 459/486 (94.4%) patients and demonstrated resolution of IDVT in 445/459 cases (96.9%). Doppler diagnosed propagation of IDVT to the popliteal vein had occurred in 10/459 (2.2%) cases. One patient with an IDVT developed a pulmonary embolus six weeks postoperatively.

CONCLUSION

The results of this study demonstrate a low rate of IDVT propagation in patients managed with aspirin. Additionally, no significant bleeding episodes, wound-related complications, or other adverse events were noted from aspirin therapy. Cite this article: Bone Joint J 2021;103-B(6 Supple A):18-22.

The anatomic distribution and pulmonary embolism complications of hospital-acquired lower extremity deep venous thrombosis

OBJECTIVE

The anatomic distribution of lower extremity deep venous thrombosis (LEDVT) plays an important role in its prevention and treatment. This study aimed to evaluate the anatomic distribution of hospital-acquired LEDVT (HA-LEDVT) and its probable role in the occurrence of pulmonary embolism (PE).

METHODS

We retrospectively analyzed the demographic data, ultrasound results, and PE-related findings of inpatients with HA-LEDVT in 28 clinical departments at Peking University People's Hospital between January 1, 2007, and December 31, 2018.

RESULTS

This study included 1431 HA-LEDVT events: 35.8%, 31%, and 33.3% were left, right, and bilateral LEDVT. Isolated distal, proximal, and blended DVT were detected in 83.4%, 7.3%, and 9.3% of the patients, respectively. The distribution of HA-LEDVT in the left and right lower extremities were not significantly different except in patients aged ≥40 years (left: 2.07 vs right: 1.88 per 1000 extremities, P = .04). For anatomic types of HA-LEDVT, isolated distal HA-LEDVT was 5.02 times more prevalent than proximal HA-LEDVT (1.24 vs 0.26 per 1000 extremities, P ＜ .01). The involvement rates of specific deep veins by HA-LEDVT were highest in the muscular calf vein (87.5%) followed by the popliteal vein (10.1%), superficial femoral vein (9.3%), and common femoral vein (9.2%). HA-LEDVT involving multiple vein segments simultaneously occurred in 338 extremities. HA-LEDVT involving the muscular calf vein and at least one of three connected axial veins of the muscular calf vein occurred most frequently. Eighty-eight patients with HA-LEDVT (6.15%) had PE. The frequency of PE among patients with proximal and distal DVT (7.89% vs 6.23% P = .275) was not significantly different. The incidence of PE was highest in patients with bilateral proximal DVT (15.4%) and lowest in patients with a single right distal DVT (4.5%). PE occurred in 6% of muscular calf vein HA-LEDVT. In isolated muscular calf vein DVT cases, PE were more likely to occur in cases with a ＞6.05-mm-diameter thrombus than in those with a ＜6.05-mm-diameter thrombus (10.3% vs 4.2%, P ＜ .0001).

CONCLUSIONS

HA-LEDVT is characterized by a significantly high percentage of DVT in the muscular calf vein. Muscular calf vein thrombosis may be the primary origin of lower extremity deep vein thrombosis. The diameter of the thrombus in the muscular calf vein may be associated with the occurrence of PE. More prospective studies are needed to more fully determine the natural history of HA-LEDVT and develop prevention and treatment guidelines for HA-LEDVT.

Clinical guidelines versus current clinical practice for the management of deep vein thrombosis

BACKGROUND

Deep vein thrombosis (DVT) is one of the major health problems worldwide with potentially serious outcomes related to mortality and morbidity. We provide a current view on how patients with DVT are managed in routine practice compared with the recommendations of published clinical guidelines.

METHODS

A literature review was conducted on studies reporting diagnostic and treatment patterns for acute DVT. Four dimensions were evaluated to compare the differences between clinical practice and clinical guidelines recommendations: diagnostic pathway, prescription of pharmacologic treatment and related duration, and prescription of compression therapy. For each aspect, the agreement with the corresponding guideline has been estimated as a percentage ranging from 0% (no agreement) to 100% (full agreement).

RESULTS

Sixteen studies reported clinical practices in 10 countries. Among them, Japan showed the highest agreement with guidelines, followed by the UK and Switzerland. Hong Kong showed the highest agreement with diagnosis guidelines, Spain for drug treatment, UK for treatment duration, and France for compression therapy. Conversely, Germany reported a complete disagreement with guidelines for diagnosis, followed by low agreement level by UK and Italy, and Switzerland reported a lower agreement level with prescription of compression therapy.

CONCLUSIONS

The implementation of clinical guidelines for the management of patients with DVT varies among countries from strict adherence to a complete lack of adherence. In this context, registries may be a useful tool to analyze clinical practice and produce findings that may be generalizable across populations.

Literature review of distal deep vein thrombosis

OBJECTIVE

Although distal deep vein thrombosis (DDVT) has been more frequently diagnosed with the availability of better ultrasound imaging quality, the data on the best method to manage DDVT have been conflicting. The aim of the present review was to summarize the current and evidence-based recommendations for the diagnosis and management of DDVT and to provide a summary of the most recent societal guideline recommendations.

METHODS

A literature review of DDVT was performed. The PubMed databases were queried for articles on the epidemiology, risk factors, diagnosis, and management of DDVT.

RESULTS

The prevalence of isolated DDVT has been reported in a broad range. The reported risk factors include older age, active malignancy, a low degree of mobility, acute infection, and atrial fibrillation. With more evidence, anticoagulation therapy was found to be associated with a reduced risk of recurrent venous thromboembolism (VTE) and/or thrombus propagation compared with conservative management. However, anticoagulation was associated with an increased risk of bleeding in a number of studies. The rate of VTE recurrence ranged from 7% to 23% during a follow-up period ranging from 3 months to 8 years. The significant risk factors for VTE recurrence included cancer, older age, an unprovoked event, and inpatient status.

CONCLUSIONS

Few studies have addressed the diagnosis and management of DDVT. Further research is needed to standardize the best approach to diagnose and treat DDVT.

Venous Doppler ultrasound in critically Ill COVID-19 patients: game changer in anticoagulation therapy

BACKGROUND

COVID-19 infection has been associated with a high rate of thrombotic events, such as deep vein thrombosis (DVT) and acute pulmonary embolism (APE).

METHODS

The purpose of our retrospective study was to evaluate the prevalence of asymptomatic DVT in lower limbs in critically ill COVID-19 patients (n = 23) with severe respiratory failure and high levels of D-dimer by bedside Doppler ultrasound (DU).

RESULTS

DVT was diagnosed in 14 cases (60.87%), 5 in proximal venous territory and 9 in infrapopliteal veins. Computed Tomography Pulmonary Angiography (CTPA) was performed in six patients and all of them showed acute pulmonary embolism (APE) at segmental or subsegmental branches of pulmonary arteries. These patients (APE or DVT confirmed) were treated with therapeutic doses of anticoagulant therapy.

CONCLUSION

In critically COVID-19 ill ICU patients with severe respiratory failure and elevated D-dimer, the incidence of asymptomatic DVT is high. We propose that DU allows detection of DVT in asymptomatic patients, adding a factor that may balance the decision to fully anticoagulate these patients.

Diagnostic Accuracy in Acute Venous Thromboembolism: Comparing D-Dimer, Thrombin Generation, Overall Hemostatic Potential, and Fibrin Monomers

Introduction  For acute venous thromboembolism (VTE), a biomarker with higher specificity than D-dimer would be of great clinical use. Thrombin generation and overall hemostatic potential (OHP) reflect the hemostatic balance by globally assessing multiple coagulation factors and inhibitors. These tests discriminate between healthy controls and patients with a prothrombotic tendency but have yet to be established as clinical biomarkers of VTE.

Objective  This study compares endogenous thrombin potential (ETP) and OHP to D-dimer and fibrin monomers (FM) in outpatients with suspected VTE.

Methods  A cross-sectional diagnostic study where 954 patients with suspected pulmonary embolism or deep venous thrombosis were recruited consecutively from the medical emergency department at Karolinska University Hospital. D-dimer, FM, OHP, and ETP were analyzed in a subpopulation of 60 patients with VTE and 98 matched controls without VTE. VTE was verified either by ultrasonography or computed tomography and clinical data were collected from medical records.

Results  Compared with healthy controls, both VTE and non-VTE patients displayed prothrombotic profiles in OHP and ETP. D-dimer, FM, ETP area under the curve (AUC), and ETP T _lag were significantly different between patients with VTE and non-VTE. The largest receiver-operating characteristic AUCs for discrimination between VTE and non-VTE, were found in D-dimer with 0.94, FM 0.77, and ETP AUC 0.65. No useful cutoff could be identified for the ETP or the OHP assay.

Conclusion  Compared with D-dimer, neither ETP nor OHP were clinically viable biomarkers of acute venous thrombosis. The data indicated that a large portion of the emergency patients with suspected VTE were in a prothrombotic state.

Treatment of distal deep vein thrombosis

BACKGROUND

The treatment of distal (below the knee) deep vein thrombosis (DVT) is not clearly established. Distal DVT can either be treated with anticoagulation, or monitored with close follow-up to detect progression to the proximal veins (above the knee), which requires anticoagulation. Proponents of this monitoring strategy base their decision to withhold anticoagulation on the fact that progression is rare and most people can be spared from potential bleeding and other adverse effects of anticoagulation.

OBJECTIVES

To assess the effects of different treatment interventions for people with distal (below the knee) deep vein thrombosis (DVT).

SEARCH METHODS

The Cochrane Vascular Information Specialist searched the Cochrane Vascular Specialised Register, CENTRAL, MEDLINE, Embase and CINAHL databases and World Health Organization International Clinical Trials Registry Platform and ClinicalTrials.gov trials registers to 12 February 2019. We also undertook reference checking to identify additional studies.

SELECTION CRITERIA

Randomised controlled trials (RCTs) for the treatment of distal DVT.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected trials and extracted data. We resolved disagreements by discussion. Primary outcomes of interest were recurrence of venous thromboembolism (VTE), DVT and major bleeding and follow up ranged from three months to two years. We performed fixed-effect model meta-analyses with risk ratio (RRs) and 95% confidence intervals (CIs). We assessed the certainty of the evidence using GRADE.

MAIN RESULTS

We identified eight RCTs reporting on 1239 participants. Five trials randomised participants to anticoagulation for up to three months versus no anticoagulation. Three trials compared anticoagulation treatment for different time periods. Anticoagulant compared to no intervention or placebo for distal DVT treatment Anticoagulation with a vitamin K antagonist (VKA) reduced the risk of recurrent VTE during follow-up compared with participants receiving no anticoagulation (RR 0.34, 95% CI 0.15 to 0.77; 5 studies, 496 participants; I² = 3%; high-certainty evidence), and reduced the risk of recurrence of DVT (RR 0.25, 95% CI 0.10 to 0.67; 5 studies, 496 participants; I² = 0%; high-certainty evidence). There was no clear effect on risk of pulmonary embolism (PE) (RR 0.81, 95% CI 0.18 to 3.59; 4 studies, 480 participants; I² = 0%; low-certainty evidence). There was little to no difference in major bleeding with anticoagulation compared to placebo (RR 0.76, 95% CI 0.13 to 4.62; 4 studies, 480 participants; I² = 26%; low-certainty evidence). There was an increase in clinically relevant non-major bleeding events in the group treated with anticoagulants (RR 3.34, 95% CI 1.07 to 10.46; 2 studies, 322 participants; I² = 0%; high-certainty evidence). There was one death, not related to PE or major bleeding, in the anticoagulation group. Anticoagulation for three months or more compared to anticoagulation for six weeks for distal DVT treatment Three RCTs of 736 participants compared three or more months of anticoagulation with six weeks of anticoagulation. Anticoagulation with a VKA for three months or more reduced the incidence of recurrent VTE to 5.8% compared with 13.9% in participants treated for six weeks (RR 0.42, 95% CI 0.26 to 0.68; 3 studies, 736 participants; I² = 50%; high-certainty evidence). The risk for recurrence of DVT was also reduced (RR 0.32, 95% CI 0.16 to 0.64; 2 studies, 389 participants; I² = 48%; high-certainty evidence), but there was probably little or no difference in PE (RR 1.05, 95% CI 0.19 to 5.88; 2 studies, 389 participants; I² = 0%; low-certainty evidence). There was no clear difference in major bleeding events (RR 3.42, 95% CI 0.36 to 32.35; 2 studies, 389 participants; I² = 0%; low-certainty evidence) or clinically relevant non-major bleeding events (RR 1.76, 95% CI 0.90 to 3.42; 2 studies, 389 participants; I² = 1%; low-certainty evidence) between three months or more of treatment and six weeks of treatment. There were no reports for overall mortality or PE and major bleeding-related deaths.

AUTHORS' CONCLUSIONS

Our review found a benefit for people with distal DVT treated with anticoagulation therapy using VKA with little or no difference in major bleeding events although there was an increase in clinically relevant non-major bleeding when compared to no intervention or placebo. The small number of participants in this meta-analysis and strength of evidence prompts a call for more research regarding the treatment of distal DVT. RCTs comparing different treatments and different treatment periods with placebo or compression therapy, are required.

Treatment of distal deep vein thrombosis

This is a protocol for a Cochrane Review (Intervention). The objectives are as follows:

To assess the effects of different treatment interventions for people with distal (below the knee) deep vein thrombosis (DVT).

Severe Leg Pain Following Spinal Cord Stimulator Implantation - A Case Report

Following spinal cord stimulator (SCS) implantation, postoperative pain is commonly incisional or neuropathic from neurological damage. Occasionally, this new pain may mimic symptoms caused by preexisting pathology. This article presents a case of immediate, severe, postoperative leg pain secondary to a lower extremity deep vein thrombosis (DVT) and subsequent pulmonary embolism after percutaneous SCS implantation for failed back syndrome. The risk factors of DVT after spine surgery and perioperative prophylaxis are further discussed with a brief literature review. LEVEL OF EVIDENCE: V.