A rapid MMP-8 bedside test for the detection of intra-amniotic inflammation identifies patients at risk for imminent preterm delivery

Abstract

Objective: Matrix metalloproteinase-8 (MMP-8) is an enzyme that is released during neutrophil activation. MMP-8 amniotic fluid concentrations are elevated not only in patients with intra-amniotic infection, but also in patients with negative amniotic fluid cultures who deliver preterm neonates. The objective of this study was to determine whether the results of a rapid MMP-8 bedside test predict imminent preterm delivery. This test can be performed in 15 minutes and without laboratory equipment.

Study design: Amniotic fluid was retrieved from 331 patients admitted with increased preterm uterine contractions and intact membranes who met the inclusion criteria. Amniotic fluid was processed for microbial cultures, Gram stain, glucose concentration, and white blood cell count. Amniotic fluid samples were stored, and the MMP-8 rapid test was performed after delivery. End points included spontaneous preterm delivery within 48 hours, 7 days, and 14 days. Diagnostic indices, predictive values, and likelihood ratios were calculated.

Results: The prevalence of spontaneous preterm delivery within 48 hours, 7 days, and 14 days was 11.6% (38/327), 20.2% (66/327), and 24.5% (80/327), respectively (4 patients with augmentation of labor were excluded). A positive MMP-8 rapid test had a positive predictive value of 70% (23/33) for the identification of patients who delivered spontaneously within 48 hours, and 94% (31/33) for patients who were delivered within 7 days and 14 days (likelihood ratios: 17.5 [95% CI, 9-33.9], 61.3 [95% CI, 15.1-250], and 50 [95% CI, 12-196], respectively).

Conclusion: The MMP-8 rapid test can identify patients at risk for preterm delivery within 7 days and 14 days. Moreover, a positive MMP-8 rapid test result can identify patients with intra-amniotic infection/inflammation with a high sensitivity and specificity. This rapid test will give clinicians a fast and accurate assessment of the inflammatory status of the amniotic cavity and allow for better identification of patients at risk for impending preterm delivery.