Objective To investigate the diagnostic value of systemic immune-inflammatory index(SII)and soluble leukocyte differentiation antigen 14 subtype(Presepsin)in women with preterm premature rupture of membranes(PROM)complicated with histological chorioamnionitis(HCA).Methods A total of 146 pregnant women with preterm PROM admitted to Suqian First Hospital from June 2021 to June 2023 were selected.They were divided into non HCA group(n=44)and HCA group(n=102)based on the presence or absence of HCA.Based on the histological staging of HCA,the preterm PROM complicated with HCA group was divided into stage Ⅰ group(n=39),stage Ⅱ group(n=33)and stage Ⅲ group(n=30).The SII,Presepsin,C-reactive protein(CRP)and procalcitonin(PCT)levels of all subjects were detected.Pearson correlation coefficient was used to analyze the correlation between these indicators.The receiver operating characteristic(ROC)curve was used to analyze the diagnostic value of SII,Presepsin and other indicators for HCA in pregnant women with preterm PROM.Results Compared with the non HCA group,the SII(638.96±168.12 vs 421.65±153.84),serum Presepsin(608.62±116.97 ng/L vs 453.84±102.15 ng/L),CRP(7.01±3.02 mg/L vs 4.35±1.86 mg/L)and PCT(0.13±0.05 μg/L vs 0.08±0.03 μg/L)of the HCA group were increased,and the differences were statistically significant(t=7.347,7.611,5.410,6.165,all P＜0.05).The levels of SII and serum Presepsin,CRP and PCT in stage Ⅰ,Ⅱ and Ⅲ groups were increased successively,and the differences were significant(F=25.794,54.230,9.459,16.774,all P＜0.05).Pearson analysis showed that SII in the HCA group was positively correlated with Presepsin,CRP and PCT(r=0.485,0.312,0.353,all P＜0.05),and Presepsin in the HCA group was positively correlated with CRP and PCT(r=0.472,0.421,P＜0.05).ROC(95％CI)analysis showed that the areas under the curve of SII and Presepsin diagnosis of pregnant women with HCA was 0.859(95％CI:0.794～0.923)and 0.877(95％CI:0.820～0.934),respectively,which was significantly larger than those of CRP(0.773,95％CI:0.699～0.847),and PCT(0.774,95％CI:0.698-0.849).Conclusion The levels of SII and Presepsin in pregnant women with preterm PROM complicated with HCA were higher,and the levels of these two indicators were closely related to the histological staging of HCA.SII and Presepsin may have high diagnostic value for preterm PROM pregnant women complicated with HCA.