Abstract: 【ABSTRACT】Objective: To investigate the correlation between the diameter of the inferior vena cava (SCI) and the blood volume of the patients with severe pregnancy induced hypertension (pregnancy induced hypertension) after cesarean section. Methods:Select our hospital surgical ICU of pregnancy induced hypertension (PIH Zhenghang cesarean section operation (without mechanical ventilation) patients as the research object,according to the central venous pressure (CVP) levels were divided into group A (CVP＜5mmHg) of the A,B CVP5-12mmHg,C group CVP＞12mmHg.The long and short diameter of the end expiratory inferior vena cava (IVC) were measured by ultrasonography in the right abdominal axillary midline position.The SCI was calculated and the correlation with Pearson was analyzed by CVP.Results:Total 43 cases were included in the study, of which a group of 10 cases, group B (22 cases) and C group (11 cases),the clinical data of the three groups of patients with age,heartrate,mean arterial pressure,lactate levels without statistical significance (P＞0.05);IVC of the long and short diameter and CVP were positively correlated,SCI and CVP were negative correlation;the ROC curve of SCI judgment CVP＜5mmHg analysis results,AUC was 0.938.Diagnosis of the critical value of 1.78,sensitivity 95.3 and specificity of 84.3;analysis of the ROC curve of SCI judgment CVP＞12mmHg results,the AUC was 0.952,community diagnosis value of 1.2,sensitivity of 94.9 specificity 85.2.Conclusion:Ultrasound measurement of the inner diameter of the inferior vena cava can be more accurate assessment of the blood volume of patients with severe pregnancy induced hypertension.