Interleukin-6 and interleukin-8 in cervical fluid in a population of Swedish women in preterm labor: relationship to microbial invasion of the amniotic fluid, intra-amniotic inflammation, and preterm delivery

Abstract

Background. Intrauterine infection and inflammation in women with preterm labor are related to adverse perinatal outcome. Due to its subclinical nature, a correct diagnosis depends on retrieval of amniotic fluid. Amniocentesis is, however, not performed as a clinical routine because of its invasiveness. Hypothetically, cytokines in the cervical fluid may represent an alternative diagnostic approach. The aim was to examine cervical interleukin (IL)-6 and IL-8 in relation to microbial invasion of the amniotic fluid, intra-amniotic inflammation, and preterm birth in women in preterm labor. Methods. Women with singleton pregnancies in preterm labor (<34 weeks of gestation) and intact membranes were included. Cervical (n = 91) and amniotic fluids (n = 56) were collected. Polymerase chain reaction for Ureaplasma urealyticum and Mycoplasma hominis and culture for aerobic and anaerobic bacteria were performed. IL-6 and IL-8 were analyzed with enzyme-linked immunosorbent assay. Results. Non-lactobacillus-dominated biota was detected in cervical secretion in 25% (22/89) and the presence of micro-organisms in the amniotic fluid in 16% (9/56) of the patients. The presence of U. urealyticum in the cervical fluid (21/46) was associated with significantly higher levels of IL-6 in the secretion. IL-6 and IL-8 were significantly higher in cervical fluid of women with intra-amniotic infection and inflammation and in women who delivered ≤7 days and/or before 34 weeks of gestation. Cervical IL-6 ≥ 1.7 ng/ml was related to intra-amniotic inflammation (relative risk: 2.67; range: 1.50–4.74) and had a sensitivity, specificity, positive predictive value, and negative predictive value of 58, 83, 75, and 69%, respectively, in the identification of intra-amniotic inflammation. Similar data were obtained for IL-8 ≥ 6.7 ng/ml. Conclusions. High levels of cervical IL-6 and IL-8 are moderately predictive of intrauterine infection/inflammation and preterm delivery.