Abstract: OBJECTIVE To explore the predictive value of red blood cell immune response and inflammatory factors in puerperal infection after cesarean section with scar uterus.METHODS A total of 400 women with scar uterus who underwent cesarean section in a three-A tertiary hospital of Zhengzhou from Oct 2018 to Oct 2020 were enrolled. selected to observe the occurrence of puerperal infection. The occurrence of puerperal infection and distribution of pathogenic bacteria were observed. The risk factors for puerperal infection after cesarean section with scar uterus were analyzed. Levels of DTER, ATER and FEIR were detected and compared between patients with puerperal infection and non-puerperal infection. The predictive value of erythrocyte immune response indicators were evaluated.RESULTS Puerperal infection occurred in 32 cases(8.00%); Gram-negative bacteria accounted for 65.00%, followed by gram-positive bacteria, accounting for 35.00%. Compared with non-puerperal infection, DTER and ATER reduced and FEIR and related inflammatory factors increased in patients with puerperal infection(P＜0.05). Postpartum hemor rhage, vaginal inflammation, DTER, ATER, FEIR, PCT, TNF-αand IL-6 were independent risk factors for puerperal infection after cesarean section with scar(P＜0.05).The values of the three indicators including DTER, ATER and FEIR in predicting puerperal infection after cesarean section with scar were higher than those of single indexes. The AUC(0.95 CI) of the combination of the three indexes was 0.916(0.858-0.977).CONCLUSION Erythrocyte immune response index has a high predictive value in puerperal infection after cesarean section with scar uterus.