Expansion
Lines of Zahn and attachment to the wall mark a true thrombus
Expansion
| Thrombus (antemortem) | Post-mortem clot | |
|---|---|---|
| Attachment | Adherent to the vessel wall | Not adherent |
| Surface | Dull, granular, lines of Zahn | Smooth, shiny, rubbery |
| Appearance | Firm, friable | “Chicken fat” yellow upper layer over “currant jelly” red lower layer |
| Shape | Conforms to the vessel, may propagate | Casts the vessel, gelatinous |
Lines of Zahn are alternating pale layers of platelets and fibrin with darker layers of red cells. They only form in flowing blood, so their presence proves the thrombus formed during life.
Arterial versus venous thrombus
- Arterial (white) thrombus: platelet rich, forms under high flow at sites of endothelial injury, typically over a ruptured plaque. Treated with antiplatelets
- Venous (red) thrombus: fibrin and red cell rich, forms in stasis. Treated with anticoagulants
“White for arteries and antiplatelets; red for veins and anticoagulants.”
Fates of a thrombus: resolution (fibrinolysis), organisation into the wall, recanalisation, propagation, or embolisation.