Interpreting D-Dimer and Fibrin(ogen) Degradation Products in Hemodialysis Vascular Access Surveillance

Background: Vascular access dysfunction remains a major source of morbidity and repeat procedures in maintenance hemodialysis (HD), with thrombosis as a key proximate event. D-dimer and fibrin(ogen) degradation products (FDP) are widely available readouts of downstream fibrin(ogen) turnover, but they are not routinely used for access surveillance and are often difficult to interpret in HD. Summary: This narrative review summarizes HD-specific biology relevant to fibrin turnover and synthesizes clinical evidence linking D-dimer and FDP to access outcomes across arteriovenous fistulas, grafts, and catheters. HD promotes a prothrombotic, hypofibrinolytic profile through uremia-related endothelial disturbance, chronic inflammation, and extracorporeal circuit effects. The clinical literature is mostly small and heterogeneous in assay platforms, sampling, and outcome definitions. Across cohorts, within-patient pre-dialysis trajectories are more consistently aligned with evolving stenosis, thrombosis, or clinically relevant dysfunction than single measurements. Interpretation remains constrained by assay and unit variability and by non-access-related influences such as inflammation and intercurrent illness. Accordingly, D-dimer and FDP are best used as contextual adjuncts within an imaging- and hemodynamics-based framework, interpreted alongside access flow measures, duplex ultrasound, and clinical assessment.