Thrombogenicity of TAE-implicated batches may be caused by an increase in the spatial clot-growth rate. (A) Clot growth was studied using a video-microscopy-based instrument, as shown in the schematic diagram. Recalcified plasma was placed in a microchamber and brought into contact with a TF-coated activator. (B) Images of growing clots in healthy plasma supplemented with the indicated concentrations of FXIa at 0, 20, and 40 minutes. The TF-coated activator is indicated by the red vertical line. Shown representative of 2--4 repeats. (C) Clot-growth rate over time periods at the indicated FXIa concentration. Shown representative of 2--4 repeats. (D) Clot size over time periods at the indicated FXIa concentration. The vertical arrow indicates increasing concentrations of FXIa. Shown representative of 2--4 repeats.