Interleukin-6 and interleukin-8 in cervical and amniotic fluid: relationship to microbial invasion of the chorioamniotic membranes

Objective To evaluate the levels of interleukin (IL)-6 and IL-8 in cervical and amniotic fluid in relation to the presence of bacteria in the membranes in women in preterm labour (PTL). Design A prospective follow up study. Setting Sahlgrenska University Hospital, Goteborg, Sweden. Sample Women with singleton pregnancies (<34 weeks) presenting with PTL (n = 30). Methods Amniotic fluid was retrieved transabdominally and cervical fluid was sampled from the uterine cervix at admission and analysed for IL-6 and IL-8 with enzyme-linked immunosorbent assay (ELISA). At birth, the chorioamniotic membranes were separated and samples for polymerase chain reaction (PCR) for Ureaplasma urealyticum and Mycoplasma hominis and general culture were obtained. Main outcome measure IL-6 and IL-8 in relation to microbial invasion of the chorioamniotic membranes. Results Bacteria were found in the membranes in 8 of 21 patients in PTL for whom chorioamnion as well as amniotic fluid PCR and cultures were available. Cervical IL-6 was associated with detectable bacteria in the chorioamniotic membranes in women in PTL (median 8.2 ng/mL vs 0.73 ng/mL; P = 0.01). The IL-6 (median 13 ng/mL vs 1.7 ng/mL; P = 0.004) and IL-8 (median 7.2 ng/mL vs 0.28 ng/mL; P = 0.01) levels in amniotic fluid were higher in PTL cases in which bacteria were found in the chorioamniotic membranes. Conclusion IL-6 in cervical fluid and IL-6 and IL-8 in amniotic fluid were higher in those PTL cases in which bacteria were found in the chorioamniotic membranes.