The 2026 annual meeting of the International Society on Thrombosis and Haemostasis (ISTH) just concluded in Paris, France. From July 11 through July 15, the 2026 ISTH Congress was five days of insightful sessions, late-breaking research presentations, and networking opportunities, bringing together global experts in thrombosis and hemostasis.

With the congress concluded, we are taking the time to showcase some of the thousands of abstracts that were presented at the 2026 ISTH Congress. The following abstracts are focused on deep vein thrombosis. Some descriptions and conclusions were edited for clarity and brevity. For the complete look at the nearly 2700 abstracts presented at the ISTH annual meeting, view the full abstract program on the conference’s official website. 

Deep Vein Thrombosis Abstracts from the 2026 ISTH Congress

Innate Immune Memory in Recurrent Deep Vein Thrombosis

  • Description: Recurrent venous thromboembolism represents a major clinical burden, yet the mechanisms underlying disease recurrence remain poorly defined. While acute deep vein thrombosis induces systemic inflammation, it is unknown whether an initial thrombotic event elicits durable alterations in hematopoiesis that predispose to subsequent thrombosis.
  • Conclusion: These findings identify thrombin-driven trained immunity in the bone marrow as a causal mechanism underlying recurrent deep vein thrombosis. Durable hematopoietic reprogramming following a first thrombotic event sustains a prothrombotic myeloid response upon recurrence. Targeting thrombin-mediated innate immune memory may represent a therapeutic strategy to reduce recurrent thrombo-inflammatory disease beyond conventional thromboprophylaxis.

Predictive Accuracy of Residual Vein Obstruction for Post-Thrombotic Syndrome in Patients with First Episode of Deep Vein Thrombosis

  • Description: Residual vein obstruction, persistent thrombotic material in veins following deep vein thrombosis, is a risk factor for recurrent deep vein thrombosis. But, its potential in predicting Post-thrombotic syndrome, a long-term debilitating complication of deep vein thrombosis, has not been studied extensively. Post-thrombotic syndrome occurs frequently in patients with recurrent deep vein thrombosis  with limited preventive strategies.
  • Conclusion: Residual vein obstruction following [the] first deep vein thrombosis episode proved to be an independent predictor of post-thrombotic syndrome with strong prediction accuracy. Early identification of residual vein obstruction can help with targeted preventive interventions to reduce post-thrombotic syndrome, a long-term complication of deep vein thrombosis.

Safely Ruling out Deep Vein Thrombosis (DVT) in Pregnancy with the LEFt Clinical Decision Rule and D-dimer (the LEaD Study): A Prospective Cohort Study

  • Description: [The researchers] hypothesized that a combination of an "unlikely" LEFt score and a negative D-Dimer could safely/efficiently exclude deep vein thrombosis in pregnancy.
  • Conclusion: An “unlikely” LEFt score and negative D-dimer may safely exclude deep vein thrombosis in pregnancy without the need for imaging. A “likely” LEFt score identifies a sub-group at high risk of venous thromboembolism meriting diligent investigation and follow-up.

Biomarkers of Endothelial Injury and Fibrinolysis Distinguish Catheter-Associated From Non-Catheter-Associated Deep Vein Thrombosis in Children: Analysis of the Kids-DOTT Trial

  • Description: Central venous catheters are the most common risk factor for pediatric deep venous thrombosis (CADVT). Emerging evidence suggests that CADVT and non-CADVT are associated with distinct pathophysiological pathways. However, such evidence is lacking in children.
  • Conclusion: Children with CADVT demonstrate persistently elevated markers of endothelial injury (VCAM, IL-8, TNF-α), suggesting thrombosis driven primarily by local vascular damage; while those with non-CADVT more frequently exhibit infection, higher BMI, elevated D-dimer, and impaired fibrinolysis, reflecting systemic hypercoagulability and metabolic dysregulation as the predominant mechanism. These findings suggest distinct pathophysiological pathways underlying pediatric venous thromboembolism subtypes.

Outcomes Post-Thrombectomy in Children: A Multi-Site Assessment of a New Non-Lytic Endovascular Device for Management of Adolescents with Extensive Acute Lower Limb Deep Vein Thrombosis

  • Description: Adolescents who develop extensive lower extremity deep venous thrombosis are at high-risk for adverse outcomes including post-thrombotic syndrome with anticoagulation alone. Catheter directed thrombolysis using tissue plasminogen activator has been reported, yet evidence-based guidelines do not routinely recommend use in pediatrics. More recently, a multi-site prospective adult registry study reported reduced post-thrombotic syndrome following treatment with a new nitinol mechanical thrombectomy device. However, there is limited data on this device in adolescents with lower extremity deep venous thrombosis.
  • Conclusion: Results suggest it is feasible to combine this new endovascular thrombectomy device in combination with intensive periprocedural anticoagulation, and that such a regimen may reduce post-thrombotic syndrome in adolescents with extensive lower limb deep venous thrombosis. Lack of bleeding events and short ICU monitoring may be advantages over endovascular thrombolysis in this population.

Risk Stratification Based on a Modified Caprini Score and Deep Vein Thrombosis After Foam Sclerotherapy

  • Description: Foam sclerotherapy is widely used for the treatment of lower limb varicose veins and, although considered safe, is not free from the risk of deep vein thrombosis. Adequate thrombotic risk stratification may support clinical decision-making regarding pharmacological prophylaxis. Adaptations of the Caprini score have been used in ambulatory venous procedures; however, data specifically addressing foam sclerotherapy are limited.
  • Conclusion: In real-world clinical practice, the adoption of an institutional thrombotic risk stratification strategy based on selected Caprini score variables prior to foam sclerotherapy was associated with a lower incidence of deep vein thrombosis within 30 days. These findings suggest that systematic thrombotic risk stratification may support clinical decision-making regarding pharmacological prophylaxis in this setting.

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