Background: Cerebral venous thrombosis (CVT) and splanchnic vein thrombosis (SVT) share prothrombotic factors, but it is unclear whether patients with both events represent a distinct phenotype with different prognosis than isolated SVT.
Objective: To describe clinical/etiological characteristics of SVT+CVT and compare presentation and SVT-related outcomes versus isolated SVT under identical eligibility criteria.
Methods: Retrospective observational cohort study using cross-linked databases (ENVIE/VALDIG, Cohort 360, BNDMR). The index date is the first imaging-confirmed SVT diagnosis date. Cases include Budd–Chiari syndrome or non-cirrhotic portal vein thrombosis with history of CVT. The date of CVT will be used to describe and analyse the temporal sequence between CVT and SVT (CVT before, after, or concomitant with SVT). Controls are isolated SVT patients from the same period, matched on age (±2 years) and sex. Comparative analyses will assess baseline features and predefined SVT-related outcomes. External validation: Main findings will be replicated in an independent multicenter VALDIG cohort using the same eligibility and matching strategy