Performance Characteristics of Putative Tests for Subclinical Chorioamnionitis

OBJECTIVE To evaluate amniotic fluid glucose, matrix metalloproteinase (MMP)-9, interleukin (IL)-6, and IL-12 for diagnosing subclinical chorioamnionitis in women with preterm labor. METHODS Forty-four women in preterm labor at 22-35 weeks gestation with suspected subclinical chorioamnionitis underwent amniocentesis. Amniotic fluid analysis included Gram stain, culture, and determination of glucose, MMP-9, IL-6, and IL-12 concentrations. Median values of these analytes were compared using the Mann-Whitney U test. Sensitivity, specificity, and positive and negative predictive values were calculated for tests using a positive amniotic fluid culture or delivery within 24 hours as the key outcome variables. RESULTS Amniotic fluid concentrations of glucose, MMP-9, and IL-6 correlated closely with positive culture or delivery within 24 hours. IL- 12 concentrations did not correlate with either a positive culture or delivery within 24 hours. CONCLUSIONS Amniotic fluid glucose, MMP-9, and IL-6 reliably predict microbial invasion of the amniotic cavity or imminent delivery. IL- 12 values did not correlate with amniotic fluid culture results or imminent delivery.