Amniotic fluid neutrophil elastase and lactate dehydrogenase: association with histologic chorioamnionitis

Chorioamnionitis (CAM) is considered to be one of the main causes of preterm labor and has been associated with an adverse perinatal outcome in preterm infants. The diagnosis of acute histologic CAM requires delivery and examination of the placenta. Although numbers of markers have been reported to predict histologic CAM before birth, it is unknown whether the levels of neutrophil elastase and lactate dehydrogenase (LDH) in amniotic fluid are associated with histologic CAM.

Sixty women at gestational age of 16-35 weeks underwent transabdominal amniocentesis within 48 hr before delivery. Amniotic fluid was analyzed for white blood cell count, glucose level, LDH level, and neutrophil elastase level. The levels of neutrophil elastase were measured by latex immunoassay. Following delivery, tissue samples were obtained from umbilical cord, chorionic plate, and placental membranes. Histologic CAM was diagnosed based on Blanc's criteria.

Receiver-operator characteristic curve analysis showed that the amniotic fluid neutrophil elastase had the best screening efficiency in predicting histologic CAM. Using amniotic fluid cut-off levels of 0.15 microg/ml for neutrophil elastase and 250 IU/l for LDH, the sensitivity, specificity, and positive and negative predictive values for predicting histologic CAM were 88.9% versus 84.1%, 73.3% versus 66.7%, 90.9% versus 88.1%, and 68.8% versus 58.8%, respectively.

Amniotic neutrophil elastase and LDH are useful markers in predicting histologic CAM.