A systematic review of histological characteristics in arterial and venous thrombi

Introduction: Despite being the leading causes of morbidity and mortality worldwide, very little is known about the similarities and differences between venous and arterial thrombi. This review is focused on comparing their structural, molecular, and temporal characteristics. Methods: A systematic review following PRISMA guidelines and focusing on arterial and venous thrombi was conducted. Only studies having histological images in vivo from animal studies and humans were included. Data on structural components and temporal changes of thrombi were collected and analyzed. Results: There were 76 articles found eligible from the full-text review. Only two studies had simultaneous temporal and spatial comparisons and did not attempt to compare the two types of thrombi: arterial and venous. Therefore, comparative insights were additionally drawn from studies analyzing one thrombus type in isolation. Four common factors were identified: red blood cells (RBCs), white blood cells (WBCs), platelets, and fibrin. Platelet concentration was higher in arterial thrombi, while more red blood cells (RBCs) were found in the venous thrombi. Conclusions: There is a clear lack of direct comparison between arterial and venous thrombi, with limited information on their evaluations. Most available findings are derived from independently conducted analyses. Registration: The protocol was registered on PROSPERO (registration ID: CRD420251003712).