Guidance for the management of venous thrombosis in unusual sites.

Venous thromboembolism (VTE) is a serious and often fatal medical condition with an increasing incidence. The treatment of VTE is undergoing tremendous changes with the introduction of the new direct oral anticoagulants and clinicians need to understand new treatment paradigms. This manuscript, initiated by the Anticoagulation Forum, provides clinical guidance based on existing guidelines and consensus expert opinion where guidelines are lacking. In this chapter, we address the management of patients presenting with venous thrombosis in unusual sites, such as cerebral vein thrombosis, splanchnic vein thrombosis, and retinal vein occlusion. These events are less common than venous thrombosis of the lower limbs or pulmonary embolism, but are often more challenging, both for the severity of clinical presentations and outcomes and for the substantial lack of adequate evidence from clinical trials. Based on the available data, we suggest anticoagulant treatment for all patients with cerebral vein thrombosis and splanchnic vein thrombosis. However, in both groups a non-negligible proportion of patients may present with concomitant bleeding at the time of diagnosis. This should not contraindicate immediate anticoagulation in patients with cerebral vein thrombosis, whereas for patients with splanchnic vein thrombosis anticoagulant treatment should be considered only after the bleeding source has been successfully treated and after a careful assessment of the risk of recurrence. Finally, there is no sufficient evidence to support the routine use of antithrombotic drugs in patients with retinal vein occlusion. Future studies need to assess the safety and efficacy of the direct oral anticoagulants in these settings.