Amniotic fluid matrix metalloproteinase-9 and interleukin-6 in predicting intra-amniotic infection

OBJECTIVE: To assess the potential role of amniotic fluid (AF) matrix metalloproteinase-9 and interleukin-6 in predicting intra-amniotic infection. METHODS: Eighty-four women with singleton gestations with preterm contraction, preterm labor, preterm premature rupture of membranes, or clinical suspicion of intra-amniotic infection were studied. Amniotic fluid was obtained by transabdominal amniocentesis before starting any treatment. Intra-amniotic infection was defined as the presence of a positive AF culture. Amniotic fluid glucose concentration, leukocytes, matrix metalloproteinase-9, and interleukin-6 were determined. RESULTS: Amniotic fluid matrix metalloproteinase-9 and interleukin-6 levels were significantly higher in women with intra-amniotic infection than in those without. With intra-amniotic infection, levels of matrix metalloproteinase-9 significantly correlated with interleukin-6 (r = 0.813, P < .001). Each of matrix metalloproteinase-9 and interleukin-6 significantly correlated with AF leukocytes and inversely correlated with AF glucose. Using AF cutoff levels of 13.6 ng/mL for matrix metalloproteinase-9 and 11.4 ng/mL for interleukin-6, the sensitivity, specificity, and positive and negative predictive values for diagnosing intra-amniotic infection were 77% versus 73%, 100% versus 79%, 100% versus 61%, and 90% versus 86%, respectively. Combining AF matrix metalloproteinase-9 with interleukin-6 slightly improved the sensitivity and the negative predictive values in diagnosing intra-amniotic infection. CONCLUSIONS: Amniotic fluid matrix metalloproteinase-9 and interleukin-6 are significantly elevated in women with intra-amniotic infection. Amniotic fluid matrix metalloproteinase-9 is an accurate biochemical marker in predicting intra-amniotic infection with better sensitivity, specificity, and positive and negative predictive values than interleukin-6.