Neutrophil elastase in amniotic fluid as a predictor of preterm birth after emergent cervical cerclage

INTRODUCTION The aim of this study was to investigate neutrophil elastase (NE) in amniotic fluid as a potential marker for predicting pregnancy continuation. MATERIAL AND METHODS We enrolled 34 pregnant women with bulging fetal membrane during the second trimester who underwent emergent cerclage after confirming the absence of intrauterine infection (amniotic fluid glucose ≥15 mg/dL). Amniotic fluid NE levels were compared between women who completed and did not complete 30, 34, and 36 weeks of gestation, and the optimal cut-off value for predicting pregnancy continuation was estimated. Moreover, the differences in the duration of continued pregnancy were compared between women with NE levels above and below the optimal cut-off value. RESULTS The optimal cut-off value for NE in amniotic fluid that predicted pregnancy continuation beyond 30, 34, and 36 weeks of gestation was 180 ng/mL; this cut-off value had a sensitivity, specificity, positive predictive value, and negative predictive value of 84.0, 77.8, 91.3, and 63.7% beyond 30 weeks of gestation; 87.5, 80.0, 91.5, and 72.3% beyond 34 weeks of gestation; and 85.0, 71.4, 80.9, and 76.9% beyond 36 weeks of gestation, respectively. The duration of continued pregnancy from emergent cerclage to delivery was significantly longer in women with amniotic fluid NE <180 ng/mL (95.1 ± 5.4 days) than in women with amniotic fluid NE ≥180 ng/mL (44.8 ± 14.3 days). CONCLUSION The NE levels in amniotic fluid may serve as a useful marker for predicting the duration of continued pregnancy after cervical cerclage.