Application Of SAA Combined With Hs-CRP And PCT In The Diagnosis And Treatment Of Intrauterine Infection In Preterm Infants

Background:Preterm infants have higher mortality and morbidity than in term infants.Intrauterine infection can cause preterm birth and impaired fetal brain development,thus aggravating near-term disease complications and long-term poor neurological outcome in preterm infants.Therefore,timely diagnosis of intrauterine infection in preterm infants and corresponding rational clinical medication are crucial to improve the prognosis of preterm infants.However,at present,the clinical diagnostic methods of intrauterine infection in premature infants are still scarce.There are no ideal inflammatory indicators with high sensitivity and specificity.Serum amyloid A(SAA),hypersensitive C-reactive protein(hs-CRP)and procalcitonin(PCT)are common inflammatory markers in the detection of intrauterine infection in preterm infants in clinical practice.However,in addition to infection,these indicators can also participate in the process of variable diseases,in which the concentration varies in different stages of diseases.It unavoidably limits their diagnostic ability in intrauterine infection of preterm infants.The importance of assessing SAA in combination with hs-CRP and PCT for early diagnosis and treatment of intrauterine infection in preterm infants is of great clinical significance,as it can improve both short-term and long-term outcomes of preterm infants.Objectives1.By comparing the differences in venous serum SAA,hs-CRP,and PCT between groups of preterm infants with maternal infection,preterm infants with maternal non-infective complications and preterm infants without maternal complications,we evaluated the significance of SAA,hs-CRP,and PCT for the diagnosis of intrauterine infection of preterm infants,and found the best reference values of SAA,hs-CRP,and PCT in the diagnosis of intrauterine infection in preterm infants.2.By comparing the differences in venous serum SAA,hs-CRP,and PCT between subgroups of preterm infants intrauterine stratified by the degree of maternal placental inflammation,gestational age,postnatal severity or short-term prognosis,we explored the relationship between maternal placental inflammation,gestational age,postnatal severity and short-term prognosis and serum SAA,hs-CRP,and PCT levels,which would provide clinical evidences for the early prevention,diagnosis and treatment of intrauterine infection in preterm infants.MethodsThis study was a prospective study.This study recruited singleton preterm infants with gestational age(GA)of 25-34 weeks,delivered in obstetrical department and transferred to NICU for treatment from June 2020 to June 2021 in Shandong Provincial Maternal and Child Health Care Hospital.All infants of their guardians agreed to enroll in this study and the relevant informed consent was signed.Infants who had a history of severe asphyxia and hypoxia,genetic or metabolic diseases,serious congenital malformations or whose mother had alcohol,tobacco or drug use(e.g.,anti-epileptic drugs,anti-psychotic drugs and other specific drugs)during pregnancy,were excluded.After the delivery of the preterm infants,the placental membranes were sent for pathological examination,venous serum levels of SAA,hs-CRP and PCT in the 6 hours after birth and 48h after treatment were detected.The intrauterine infection group was preterm infants who met the diagnostic criteria for intrauterine infection and had no other pregnancy complications;the non-infective complication group was preterm infants with non-infective complications but no signs of intrauterine infection;the control group was preterm infants with no infective and non-infective complications.Comparisons of serum SAA,hs-CRP,and PCT in three group were conducted to evaluate the importance and reference values of serum SAA,hs-CRP,and PCT levels in the diagnosis of intrauterine infection in preterm infants.Preterm infants with intrauterine infection were further divided into different subgroups according to the degree of maternal placental inflammation,gestational age,postnatal severity or short-term prognosis.According to the histological pathology results of the placenta,preterm infants with intrauterine infection were divided into:no chorioamnionitis group,acute chorionitis group and acute chorioamnionitis group.According to the mother’s prenatal antimicrobial use,preterm infants with intrauterine infection were classified as:≥3 d antimicrobial use group,<3 d antimicrobial use group,and no antimicrobial use group.According to the gestational age,preterm infants with intrauterine infection were divided into:Very preterm infants(GA 28-31+ 6 W)and Moderate preterm infants(GA 32-33+6 W).According to the neonatal critical score,preterm infants with intrauterine infection were divided into:non-risk,risk and extreme risk group.According to the short-term outcomes after 48h of treatment,preterm infants with intrauterine infection were divided into:improved group and aggravated group.We compared the differences in venous serum SAA,hs-CRP,and PCT between different subgroups of preterm infants with intrauterine infection stratified by aforesaid potential influencing factors.Results1.Serum SAA,hs-CRP and PCT in the intrauterine infection group were all significantly higher than the non-infective complication group,and even more significantly higher than the control group,with statistically differences between groups.ROC curve analysis revealed that the area under the curve for serum SAA,hs-CRP,PCT and combined diagnosis of intrauterine infection were 0.827,0.865,0.909 and 0.912,respectively.The optimal cut-off values for SAA,hs-CRP,and PCT were 7.25 mg/L,5.65 mg/L,and 0.635 ng/mL，respectively.The sensitivity and specificity of combined SAA,hs-CRP and PCT for the diagnosis of intrauterine infection were 93.2%and 96.1%,respectively,higher than those of any single indicator.2.In preterm infants with intrauterine infection,the serum SAA,hs-CRP and PCT in infants without chorioamnionitis were all significantly lower than those with acute choriitis,and even more significantly lower than those with acute chorioamnionitis,all of which had statistical significance(P<0.05).3.In preterm infants with intrauterine infection,serum SAA,hs-CRP and PCT in the>3 d antimicrobial use group were significantly lower than<3 d antimicrobial use group,and more significantly lower than no antimicrobial use group,differences were all statistically significant(P<0.05).4.In preterm infants with intrauterine infection,there were no statistical differences in serum SAA,hs-CRP and PCT levels in very and moderate preterm infants(P>0.05).5.In preterm infants with intrauterine infection,serum SAA,hs-CRP and PCT in extreme risk preterm infants were significantly higher than risk infants,and even more significantly higher than non-risk infants,all with significant differences between subgroups(P<0.05).6.In preterm infants with intrauterine infection,serum SAA,hs-CRP and PCT after 48 hours of treatment were all significantly lower than those at 6 hours after birth in the improved group;while they were all significantly higher than those at birth in the aggravated group(P<0.05).Conclusion1.Preterm infants with intrauterine infection exhibited significantly higher serum SAA,hs-CRP and PCT levels;Combined tests of three indicators demonstrated best sensitivity and specificity than any single indicators.The optimal cut-off for SAA,hs-CRP and PCT was 7.25 mg/L,5.65 mg/L,0.635 ng/ml,respectively.2.Serum SAA,hs-CRP,and PCT in preterm infants with intrauterine infection were associated with the severity of placental inflammation,maternal prenatal antibiotic use,disease severity,and outcome,independent of gestational age.3.Serum SAA,hs-CRP and PCT,which had significance in assessing the intensity of infection,antibiotics administration and clinical treatment effects.