Abstract: Objective　To investigate the clinical application significance of neutrophil VCS parameters in the detection of acute bacterial infection and the stringency diseases with cardiovascular or cerebrovascular accident，major surgery operation and acute gastrointestinal hemorrhage.   Methods　A total of 128 patients with acute bacterial infection，56 patients with acute cardiovascular or cerebrovascular disease，51 patients after major surgery operation，42 patients with acute gastrointestinal hemorrhage and 50 healthy subjects were enrolled in the study. The neutrophil VCS parameters were determined by Coulter LH-750 hematology analyzer. The parameters included mean neutrophil volume（MNV），mean neutrophil conductivity（MNC），mean neutrophil scatter（MNS） and neutrophil volume distribution width（NDW）. Results　The results of acute bacterial infection group were as follows：MNV（154.90±7.61）fL，MNC 146.02±2.56，MNS 134.13±6.18 and NDW 24.88±3.57.The results of acute cardiovascular or cerebro vascular disease group were as follows：MNV（144.50±6.52）fL，MNC 146.64±2.60，MNS 139.00±3.50 and NDW 20.40±2.34. The results of acute gastrointestinal hemorrhage group were as follows：MNV（147.42±5.00）fL，MNC 147.00±3.10，MNS 138.00±3.91 and NDW 21.51±2.50. The results of major surgery operation group were as follows：MNV（150.84±5.96）fL，MNC 146.20±3.13，MNS 136.80±4.87 and NDW 22.75±1.99. The results of healthy control group were as follows：MNV（140.22±4.27）fL，MNC 147.21±2.05，MNS 142.42±6.18 and NDW 18.56±1.15.There were statistical significances of MNV，MNS and NDW between acute bacterial infection，acute cardiovascular or cerebrovascular disease，acute gastrointestinal hemorrhage and major surgery operation groups with healthy control group（P＜0.01）. The changes of MNV，MNS and NDW in acute bacterial infection group were the most obvious among those 4 groups. The results of stringency disease group，including acute cardiovascular or cerebrovascular disease group，major surgery operation group and acute gastrointestinal hemorrhage group，were as follows：MNV（147.50±6.29）fL，MNS 137.50±4.70 and NDW 21.66±2.54. The differences of these parameters between stringency disease group and acute bacterial infection group had statistical significance（P＜0.01）. Conclusions　The neutrophil VCS parameters can reflect the morphologic changes of neutrophil in acute bacterial infection and common stringency diseases，and the change in acute bacterial infection is more obvious than that in common stringency diseases.

Key words: VCS parameter, Neutrophil, Bacterial infection, Stringency reaction