AMNIOTIC-FLUID INTERLEUKIN-6 DETERMINATIONS ARE OF DIAGNOSTIC AND PROGNOSTIC VALUE IN PRETERM LABOR

PROBLEM: The purpose of this study was to determine if amniotic fluid concentrations of the interleukin-6 (IL-6) are of value in diagnosis o f microbial invasion of the amniotic cavity and in the prediction of f ailure of tocolysis, preterm delivery and perinatal morbidity and mort ality. METHOD: Amniotic fluid was obtained by transabdominal amniocent esis from 146 consecutive patients admitted with the diagnosis of pret erm labor and intact membranes. Fluid was cultured for aerobic and ana erobic bacteria as well as for mycoplasmas. Amniotic fluid IL-6 levels were measured using a monoclonal antibody-based enzyme-linked immunos orbent assay with a sensitivity of 0.03 ng/ml. Logistic regression and Cox's proportional hazards model were used to examine the effect of s everal variables on dichotomous outcomes or interval to delivery. RESU LTS: Patients with a positive amniotic fluid culture had a significant ly higher amniotic fluid IL,6 concentrations than patients with a nega tive culture (median 91.2 ng/ml, range 0.9 to 437 ng/ml versus median 0.4 ng/ml, range <0.3 to 195 ng/ml, respectively; P<.0001). An amnioti c fluid IL-6 concentration of greater than or equal to 11.3 ng/ml had a sensitivity of 93.3% (14 of 15) and a specificity of 91.6% (120 of 1 31). All patients with an amniotic fluid IL-6 concentration above 11.3 ng/ml and a negative amniotic fluid culture (N = 11) delivered preter m and all placenta available for examination (N = 7) had histologic ev idence of chorioamnionitis. Amniotic fluid concentrations of IL-6 were an independent predictor of preterm delivery, amniocentesis-to-delive ry interval and neonatal morbidity and mortality. Moreover, IL-6 conce ntrations added significant information to the prediction of these out comes to that provided only by clinical information such as cervical d ilatation, gestational age at admission or at delivery. CONCLUSION: IL -6 is a sensitive and rapid test for the detection of microbial invasi on of the amniotic cavity and for identifying women at risk for sponta neous preterm delivery and neonates at risk for morbidity and mortalit y.