Significance of cervical secretion culture in predicting maternal and fetal outcome in pregnant women with premature rupture of membranes: a retrospective cohort study

Abstract

Background: To investigate the clinical value of cervical secretion culture in pregnant women with premature rupture of membranes (PROM) in predicting maternal and fetal outcomes. Methods: We retrospectively reviewed clinical records of pregnant women who underwent obstetric examination and delivered in Fujian Maternal and Child Healthcare from December 2013 to December 2016. Pregnant women with a clear diagnosis of PROM, who underwent cervical secretion culture immediately after hospital admission were selected for the study. The primary outcome was the occurrence of chorioamnionitis. The secondary outcome was neonatal admission to the neonatal intensive care unit (NICU). Correlation between maternal and fetal outcomes and the results of the cervical secretion culture was analyzed by one-way analysis and multifactorial analysis, respectively. The predictive efficacy of cervical secretion culture was evaluated using receiver operating characteristic curve (ROC), area under the curve (AUC) and the integrated discrimination improvement (IDI). Results: A total of 7,727 pregnant women with PROM were included in the study. Of them, 1812 had positive cervical secretion cultures (635 positive for mycoplasma infection, 475 for bacterial, 637 for fungal, and 65 for chlamydial infections). Pregnant women with positive mycoplasma and bacterial cultures had higher rates of developing chorioamnionitis compared to women with negative cervical secretion cultures (9%, 12% vs. 1%, respectively). Similarly, positive mycoplasma and bacterial cultures were associated with higher rate of the preterm (before 34 weeks) labor (3%, 3% vs. 1% in women with negative cultures, respectively), and neonatal admission to the NICU (9%, 11% vs. 7%, respectively). After adjusting for various confounding factors, our analysis demonstrated that a positive cervical secretion culture for mycoplasma or bacterial pathogens remained an independent risk factor for chorioamnionitis. Cervical secretion culture outcome was less effective in predicting chorioamnionitis (AUC 0.569) compared to white blood count (WBC) (AUC 0.626) and C-reactive protein (CRP) levels (AUC 0.605). The IDI of the combined predictive model incorporating WBC, CRP, maternal fever and cervical secretion culture results was 0.0029^. Conclusion: Positive cervical secretion cultures, especially for mycoplasma and bacteria, are associated with higher incidence of adverse maternal and fetal outcomes. However, the predictive value of this test is poor, and cannot be efficiently used for predicting chorioamnionitis.

Keywords: cervical secretion cultures; chorioamnionitis; pregnant women; premature rupture of membranes; retrospective cohort study.

FIGURE 1

Flowchart of participants selection for the cohort.

FIGURE 2

ROC curve for CRP, WBC, Cervical secretions culture and combination models.