| Research background and purpose:In recent years,premature birth has become the main disease in the neonatal department,and there are many causes.Among them,intrauterine infection is one of the most important causes,and the incidence of complications and mortality of preterm infants with intrauterine infection has increased significantly.Therefore,timely diagnosis and treatment of intrauterine infection in preterm infants is of great significance for improving the prognosis of preterm infants with intrauterine infection.However it is still a tough problem to make a quick and accurate diagnosis,and there is no sensitive and specific early diagnosis method.Interleukin-6(IL-6),a pro-inflammatory cytokine,which participates in various disease processes and rises in varying degrees,has attracted widespread attention to the early diagnosis of intrauterine infection in preterm infants.However,some studies have found that IL-6levels may also increase in non-infection comorbidities in the perinatal period,thereby limiting the value of IL-6 in the diagnosis of intrauterine infection in preterm infants.The first purpose of this study is to compare the differences in serum IL-6 levels between the preterm infants with non-infectious maternal comorbidities and those with intrauterine infection,and to explore the significance of serum IL-6 level in diagnosis of intrauterine infection in preterm infants by detecting the level of IL-6 in maternal blood,cord blood and neonatal venous blood of preterm infants,combined with the results of placental pathology.The second purpose is to provide clinical evidence for the diagnosis and intervention of preterm infants with intrauterine infection by investigating the correlation between maternal placental inflammation and IL-6 in preterm infants with intrauterine infection,the effect of maternal prenatal antibiotic use on serum il-6 level in preterm infants with intrauterine infection,and the relationship between the change of IL-6 level with the occurrence and short-term prognosis of postnatal infectious diseases of preterm infants.Methods:Adopting prospective research design,I chose the preterm infants(gestational age28-36 weeks;single live births),who were delivered in the obstetrics department of Ya’an People’s Hospital from January to December 2019 and admitted to the hospital’s neonatal department.Their placenta was sent for pathological examination.At the same time,the level of IL-6 in serum(maternal blood before delivery,cord blood and venous blood of preterm infants at birth,venous blood of preterm infants 48 hours after treatment)were measured by electrochemical luminescence.First of all,those who met the diagnostic criteria for intrauterine infection without other comorbidities were included in the intrauterine infection group,those with maternal non-infectious comorbidities were included in the non-infectious comorbidity group,and those without evidence of infection and mothers without comorbidities were included in the control group.Serum IL-6 level in each group was compared to explore the significance of serum IL-6 level in the diagnosis of intrauterine infection in preterm infants.Secondly,preterm infants with intrauterine infection were divided into non chorioamnionitis group,chorioamnionitis stage I group,and chorioamnionitis stage II group according to the results of placental examination.The relationship between maternal placental inflammation and serum IL-6 levels in preterm infants with intrauterine infection was investigated.Thirdly,preterm infants with intrauterine infection were divided into prenatal antibiotics for mothers ≥ 3 d group,<3 d group and unused group according to the course of antibiotics used by their mothers before delivery.The effects of prenatal antibiotic use on serum IL-6 levels in preterm infants with intrauterine infection were explored.Finally,preterm infants with intrauterine infection were grouped according to the gestational age,illness,IL-6 levels and the outcome 48 hours after treatment.The levels of IL-6 and the incidence of related diseases were compared in each group,to explore the relationship between the level of IL-6 and the incidence and short-term prognosis of postnatal diseases of preterm infants with intrauterine infection.Result:1.Comparative study of IL-6 levels in preterm infants with intrauterine infection and non-infectious maternal comorbiditiesThe levels of IL-6 in maternal blood,umbilical cord blood,and neonatal serum were significantly higher in the intrauterine infection group than in the non-infectious comorbidity group and the control group,and the differences were statistically significant(P<0.05).Only the level of IL-6 in maternal blood was higher in the non-infectious comorbidity group than in the control group,and the difference was statistically significant(Z=-6.552,P<0.001).There was no statistically significant difference in the levels of IL-6 in cord blood(Z=-0.028,P= 0.978)and newborn blood(Z=-0.450,P=0.653).The areas under the ROC curve for predicting intrauterine infection in preterm infants with IL-6 in maternal,umbilical,and neonatal blood were0.877,0.881,and 0.924,respectively.The optimal cutoff values for IL-6 in maternal blood,cord blood,and neonatal serum were 14.95 pg/ml,3.25 pg/ml,and 4.25 pg/ml.Among the three indices,the levels of IL-6 in the newborn’s blood predicted the highest sensitivity and specificity of intrauterine infection in preterm infants,respectively 89.1 % and 96.4 %.The area under the ROC curve of maternal blood IL-6level for predicting maternal non-infectious comorbidities was 0.907,and the maternal blood IL-6 level cut-off value was 5.50 pg/ml,and its sensitivity and specificity were93.0 % and 87.5 % respectively.2.Application of IL-6 detection in the treatment of preterm infants with intrauterine infection.Serum IL-6 levels in preterm infants of chorioamnionitis group were higher than in the non chorioamnionitis group,and in the cases of non chorioamnionitis,chorioamnionitis stage Ⅰ and stage Ⅱ cases,there was an increasing trend in order,and the difference was statistically significant(P<0.05).The serum levels of IL-6 in preterm infants whose mothers used antibiotics before birth(≥3 d,<3 d)were lower than those in unused cases,and the difference was statistically significant(P<0.05).There was no significant difference in serum IL-6 levels between preterm infants of different gestational ages(P>0.05).The serum IL-6 level of preterm infants at birth showed an increasing trend in the non-critical group,the critical group and the extremely critical group,but there was no significant difference among the three groups(P>0.05).The serum IL-6 level in the improved condition group after 48 hours of treatment was lower than that at birth,and the serum IL-6 level in the disease plus recombinationafter 48 hours of treatment was higher than that at birth,and the difference was statistically significant(P<0.05).There was no significant difference in the incidence of PVL,PIVH,ROP,and BPD in preterm infants with IL-6>7 pg/ml and ≤7 pg/ml(P>0.05).Conclusion :1.During intrauterine infection,the levels of IL-6 in maternal blood,umbilical cord blood,and neonatal blood increased significantly,while only the level of IL-6 in maternal blood increased during non-infection comorbidities.Among them,neonatal blood IL-6 level is the most sensitive for intrauterine infection,which helps to distinguish maternal infection from non-infectious comorbidities.Therefore,the serum IL-6 level at birth has important significance for the diagnosis of intrauterine infection in preterm infants.2.The level of IL-6 in venous blood of preterm infants with intrauterine infection increased,which was related to the severity of placental inflammation.Prenatal antibiotics used by mothers can effectively reduce serum IL-6 levels in preterm infants with intrauterine infection,and serum IL-6 levels are related to clinical treatment effects.There is no necessary link between the levels of IL-6 at birth and the incidence of PVL,PIVH,ROP,and BPD in preterm infants with intrauterine infection.Therefore,serum IL-6 level has certain reference significance for evaluating the severity of infection,guiding the application of antibiotics and evaluating the efficacy. |
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