Microclots are associated with critical illness. (A) Microclots were characterized according to number of microclots per field (counts per field). Typical images are presented. (B) The number of microclots (counts per field) were compared between patients on admission to the ICU (n = 104) and paired fresh and frozen (n = 10) and historical (n = 10) normal healthy controls. (C) Microclots were characterized according to size (pixels per field). Typical images are presented. (D) The size of microclots (pixels per field) were compared between patients on admission to the ICU (n = 104) and paired fresh and frozen (n = 10) and historical (n = 10) normal healthy controls. (E) Microclot number and size were compered between ICU patients with nonsepsis (n = 62) and sepsis (n = 42). (F) Microclot number and size were compared between patients diagnosed with DIC (n = 19) and those without DIC (n = 85). Continuous data presented in panels B,D,E-F were analyzed using Mann-Whitney U test.