Introduction
A high proportion of preterm premature rupture of membranes (PPROM) occurring before 34 weeks of gestation are associated with chorioamnionitis (CA), which is caused primarily by the ascending bacterial invasion of the vagina, leading to infection of fetal membranes, placenta, amniotic fluid, and uterine cavity[1-3]. Chorioamnionitis could be divided into clinical CA (CCA) and histological CA (HCA). CCA is diagnosed based on the presence of clinical evidence before or during labor and delivery; HCA is identified from the evidence of infection and inflammation in the examination of the placenta[4, 5], with its clinical course often asymptomatic and its prevalence higher than CCA[6, 7]. In addition, HCA was associated with early-onset sepsis and combined perinatal comorbidities in infants, which are of more diagnostic importance than CCA alone[8]. However, confirmation of HCA through pathological examination of the placenta is unable to provide an early warning for the treatment of newborns. Therefore, it is vitally important to explore a sensitive and accurate diagnostic biomarker for early detection of histological chorioamnionitis that may allow for early intervention and treatment of newborn infants.
As is well known, monitoring of maternal serum infectious indicators including WBC, neutrophil, lymphocyte, CRP and PCT levels may assist in early diagnosis of infection. However, antenatal corticosteroid therapy, including either betamethasone or dexamethasone for women in preterm labor[9, 10] have shown a transient increase in maternal WBC and neutrophil, which is easily confused with chorioamnionitis and induces unnecessary early termination of the pregnancy[11-13]. Although some studies have shown that this increase was physiologic leukocytosis after corticosteroid administration, most of those results were merely obtained from PPROM patients without chorioamnionitis, lacking the comparison of data from a HCA group. In addition, procalcitonin (PCT), secreted by thyroid C-cells, is markedly elevated in many bacterial infections and can be used as a prognostic infectious indicator of sepsis[14]. However, its role as a biomarker for the detection of HCA in PPROM is still controversial[15-17]. Furthermore, the constant response of PCT after injection of corticosteroids has not been fully investigated.
Consequently, this retrospective study was conducted to thoroughly investigate the dynamic responses of maternal WBC, neutrophil, lymphocyte, CRP and PCT to antenatal dexamethasone in PPROM women, compare the differences of the above serum indicators between the CON women and HCA group, and determine the predictive value of CRP and PCT for predicting HCA by analyzing dynamical changes constantly.