Clinical risk factors for deep venous thrombosis in pregnancy and the puerperium

Sulfated non-anticoagulant low molecular weight heparin in the prevention of cancer and non-cancer associated thrombosis without compromising hemostasis

INTRODUCTION

Cancer-associated thrombosis (CAT) accounts for about 20% of all cases of Venous Thromboembolism (VTE). Tissue factor (TF) is documented to be highly expressed on cancer cells and pathological angiogenic endothelial cells. Here, we used a novel oxidized sulfated ultra-LMWH, S-NACH, which is devoid of anti-factor Xa and IIa activities with limited to no systemic anticoagulant effects. This sulfated form has enhanced binding to vascular endothelial cells (EC) and releases and potentiates the action of tissue factor pathway inhibitor (TFPI). S-NACH binds with high affinity to EC, releases and binds to EC TFPI, and promotes vascular antithrombotic effect with limited to no risk of bleeding complications.

MATERIALS AND METHODS

We investigated the effects of S-NACH on clot kinetics in vitro and in vivo. Also, we investigated the effects of S-NACH on CAT mediated by human acute leukemia cells (K562) and human pancreatic cancer cells (SUIT2).

RESULTS

S-NACH was associated with ~3-fold increase of TFPI 2 levels within 3 h. Also, S-NACH reversed the hypercoagulability state that is associated with cancer cells in vitro. In vivo, S-NACH at 20 mg/kg subcutaneously (SC) had no effect on bleeding time compared to both tinzaparin and enoxaparin at 5 mg/kg SC. S-NACH did not show any anti-IIa or anti-Xa activities in comparison to tinzaparin and enoxaparin (p < 0.001).

CONCLUSION

Data suggest the importance of S-NACH through its EC binding, EC TFPI release and its interaction with TFPI in enhancing its activity in the prevention of cancer and non-cancer associated thrombosis with limited to no bleeding complications.

Anatomic distribution of deep vein thrombosis in pregnancy

BACKGROUND

Prospective studies of nonpregnant patients have demonstrated that most deep vein thromboses of the lower extremity originate in the calf veins and progress proximally, but the anatomic distribution of thromboses in pregnant patients is unclear. An understanding of the anatomic distribution of deep vein thrombosis in pregnancy has important implications for optimizing diagnostic imaging protocols. We undertook this study to determine the anatomic distribution of deep vein thrombosis of the lower extremity in symptomatic pregnant patients.

METHODS

We systematically searched MEDLINE (1966 to January 2009), Embase (1980 to January 2009) and the Cochrane Library using prespecified criteria to identify articles providing objective diagnostic and anatomic information for unselected or consecutive symptomatic pregnant patients with deep vein thrombosis.

RESULTS

Six articles from an initial list of 1098 titles met the inclusion criteria. These articles provided information for 124 pregnant women with a diagnosis of deep vein thrombosis. Overall, involvement of the left leg was reported in 84 (88%) of the 96 patients for which the side affected was known, and 87 (71%) of 122 thromboses were restricted to the proximal veins without involvement of the calf veins. Among these cases of proximal deep vein thrombosis, 64% (56/87) were restricted to the iliac and/or femoral vein.

CONCLUSION

Despite a paucity of studies in this area, the results of our review suggest that the anatomic distribution of deep vein thrombosis in pregnant women differs from that for nonpregnant patients. In addition to what was previously known--that left-sided deep vein thrombosis is more common in pregnancy--we also found that proximal deep vein thrombosis restricted to the femoral or iliac veins is also more common (> 60% of cases). If confirmed by larger studies, these findings could affect our understanding of the pathophysiology and derivation of diagnostic algorithms for examination of pregnant women with suspected deep vein thrombosis.

Venous Thromboembolism in Obstetrics and Gynecology

The diagnosis of venous thromboembolism can present a clinical challenge. Using D-dimer testing and spiral or helical computed tomography scans has simplified the diagnosis of venous thromboembolism. In addition, the use of low molecular weight heparin has become widely accepted in the prevention and treatment of venous thromboembolism. However, further studies are needed to determine optimal prevention and treatment strategies, particularly in the obstetric population.

Comparison of incidence/risk of venous thromboembolism (VTE) among selected clinical and hereditary risk markers: a community-based cohort study

Background

Little information is available from community-based long-term VTE cohort studies to compare the absolute thrombosis risk of established clinical and genetic risk factors.

Materials and methods

The occurrence of venous thromboembolism (VTE) was observed during a 10-year observation period in the BAvarian ThromboEmbolic Risk (BATER) study, a cohort study of 4337 women (age 18–55 years). We collected data on demographics, reproductive life, lifestyle, conditions/diseases, and particularly potential risk factors for VTE with a self-administered questionnaire. The objective was to present incidence rates of VTE and to show relative risk estimated associated with different clinical and genetic risk factors.

Results

34 new, by diagnostic means confirmed VTE events occurred during the observation time of 32,656 women-years (WY). The overall incidence of VTE was 10.4 per 10⁴ WY. The incidence rates varied markedly among different risk cohorts. The highest incidence was observed in women with previous history of VTE, followed by family history of VTE. None of the measured "genetically-related risk markers" (antithrombin, protein C, FVL, prothrombin mutation, or MTHFR) showed a significant VTE risk.

Conclusion

Most of the discussed VTE risk factors showed no significant association with the occurrence of new VTEs due to smallness of numbers. Only first-degree family history of VTE and own history of a previous VTE event depicted a significant association with future VTE. Clinical information seems to be more important to determine future VTE risk than genetically related laboratory tests.