A computational model suggests elevated hematocrit increases the time that platelets spend in proximity to a thrombus. Simulations of whole blood flow with 40% (A, C, E, G) and 60% (B, D, F, H) hematocrit were conducted as described in “Methods.” (A-B) Snapshots showing instantaneous positions of RBCs (red) and platelets (black) for (A) 40% and (B) 60% hematocrit in flowing blood indicate RBCs are less prevalent close to vessel walls and platelets are more prevalent in this near-wall RBC-depleted zone. (C-D) Time-averaged RBC distribution for flow past a small thrombus (filled circles) in (C) 40% and (D) 60% hematocrit. The near-wall depleted zone is narrower in higher hematocrit. Scale indicates relative RBC distribution. (E-H) Time-dependent progression (2-millisecond intervals) of an individual platelet (blue) over a small or large thrombus (black circles): (E) 40% hematocrit, small thrombus, (F) 60% hematocrit, small thrombus, (G) 40% hematocrit, large thrombus, (H) 60% hematocrit, large thrombus. For both the small and the large thrombus, the platelet spends substantially more time near the thrombus for 60% hematocrit than for 40% hematocrit. Bars indicate 10 µm.