Value of amniotic fluid neutrophil collagenase concentrations in preterm premature rupture of membranes.

OBJECTIVE

Neutrophils in amniotic fluid are thought to be of fetal origin, and therefore the detection of these cells and/or their products in amniotic fluid may reflect the fetal inflammatory status. We propose that amniotic fluid neutrophil collagenase (matrix metalloproteinase-8) is a useful parameter to predict adverse neonatal outcome, impending preterm labor/delivery, and intrauterine infection in the setting of preterm premature rupture of the membranes.

STUDY DESIGN

Amniotic fluid was obtained by transabdominal amniocentesis from 101 patients with preterm premature rupture of the membranes (gestational age, 24-36 weeks). Fluid was cultured for aerobic and anaerobic bacteria and Mycoplasmas. Amniotic fluid analysis included Gram stain, white blood cell count, and determination of interleukin-6 and matrix metalloproteinase-8 concentrations (enzyme-linked immunosorbent assay).

RESULTS

Neonates with adverse neonatal outcome were born to mothers with a significantly higher median amniotic fluid matrix metalloproteinase-8 concentration than those without adverse neonatal outcome (median, 54.4 ng/mL; range, 0.82-14,500 ng/mL vs median, 28.9 ng/mL; range, 0.78-2451.8 ng/mL; P <.05, respectively). The higher the amniotic fluid matrix metalloproteinase-8 concentrations, the shorter the interval to delivery (Cox proportional hazards model adjusting for gestational age at delivery; hazard ratio, 1.9; 95% CI, 1.1-3.5; P <.03). Amniotic fluid matrix metalloproteinase-8 concentration was more sensitive than an amniotic fluid white blood cell count and interleukin-6 in the detection of microbiologically proven intra-amniotic infection.

CONCLUSION

Increased concentrations of neutrophil collagenase (matrix metalloproteinase-8) in amniotic fluid are associated with intra-amniotic infection, impending preterm delivery, and adverse neonatal outcome in patients with preterm premature rupture of the membranes. Moreover, matrix metalloproteinase-8 in amniotic fluid is a stronger predictor for the duration of pregnancy and intra-amniotic inflammation than interleukin-6 and an amniotic fluid white blood cell count.