Elevated amniotic fluid nitric oxide metabolites and cyclic guanosine 3',5'-monophosphate in pregnant women with intraamniotic infection

OBJECTIVE: Our purpose was to compare amniotic fluid nitric oxide metabolites and cyclic guanosine 3',5'-monophosphate in pregnant women with and without intraamniotic infection. STUDY DESIGN: Amniocentesis was performed on 72 pregnant women with preterm contractions, labor, or rupture of membranes. Fourteen patients had intraamniotic infection and 58 did not. Intraamniotic infection was defined as the presence of a positive amniotic fluid culture. Amniotic fluid Gram stain, glucose, leukocyte counts, leukocyte esterase activity, creatinine, pH, and specific gravity were performed. Endogenous nitrite was determined using Griess reagent. Amniotic fluid nitric oxide metabolites (nitrite and nitrate) were measured after reduction of nitrate to nitrite with Aspergillus nitrate reductase. Tests for amniotic fluid cyclic guanosine monophosphate levels were determined by enzyme immunoassay. Two-tailed t test, contingency table methods, linear regression, and correlation were used for statistical analyses. RESULTS: Amniotic fluid levels of nitric oxide metabolites, endogenous nitrite, nitrate, and cyclic guanosine monophosphate were significantly higher in pregnant women with intraamniotic infection than in those without intraamniotic infection (2.66 ± 0.49 vs 1.77 ± 0.07 μmol/mg creatinine p = 0.002; 0.69 ± 0.15 vs 0.38 ± 0.03 μmol/mg creatinine, p = 0.003; 1.99 ± 0.41 vs 1.38 ± 0.07 μmol/mg creatinine, p = 0.02; and 1.47 ± 0.22 vs 0.90 ± 0.08 nmol/mg creatinine, p = 0.004, respectively). Both amniotic fluid nitric oxide metabolites and cyclic guanosine monophosphate were positively correlated with amniotic fluid leukocyte counts and leukocyte esterase activity and negatively correlated with amniotic fluid glucose concentrations. CONCLUSIONS: Our data indicate that amniotic fluid nitric oxide and cyclic guanosine monophosphate may play important roles in the pathogenesis of intraamniotic infection. Measurements of amniotic fluid nitric oxide metabolites and cyclic guanosine monophosphate may be part of a panel of tests that can be used to detect intraamniotic infection.