Measurements of Interleukin-8 and Matrix Metalloproteinases-9 in Cervicovaginal Fluid in Women with Preterm Labor: A Direct Comparison with Amniotic Fluid

Abstract

Objective  We aimed to evaluate the correlation and agreement of interleukin (IL)-8 and matrix metalloproteinases (MMP-9) levels between cervicovaginal (CVF) and amniotic fluids (AF) in women with preterm labor (PTL) and to determine the clinical values of these proteins in CVF compared with those in AF. Study Design We designed a retrospective cohort study of 85 singleton pregnant women with PTL at 23 to 34 weeks, who underwent amniocentesis. The AF was cultured, and CVF samples were collected at the time of amniocentesis. Paired AF and CVF samples were assayed for IL-8 and MMP-9 by enzyme-linked immunoassay (ELISA) in duplicate on a single plate, using similar dilution ratios. Results A significant but weak correlation was found for IL-8 levels between AF and CVF (r = 0.333), while no correlation was found for MMP-9 levels between AF and CVF (r = −0.039). Intra-class correlation coefficient for the agreement of IL-8 levels between CVF and AF was 0.4335 and −0.279 for MMP-9, indicating a poor-to-fair level of agreement between the two measured values, respectively. IL-8 and MMP-9 levels in CVF were not associated with the risk of either microbial invasion of the amniotic cavity (MIAC) or spontaneous preterm delivery (SPTD) within 7 days, whereas those in AF provided good-to-excellent predictive values for these two outcomes (area under the curve [AUCs]: 0.82–0.95). AUCs for IL-8 and MMP-9 were significantly larger using AF rather than using CVF for the prediction of MIAC and SPTD. Conclusions In women with PTL, IL-8 and MMP-9 levels in CVF do not precisely reflect the levels of the corresponding proteins in AF. IL-8 and MMP-9 levels in CVF had poor predictive values for the risk of MIAC and SPTD and were significantly inferior to those in AF. Key Points