Amniotic Fluid Glucose Concentration: A Marker for Infection in Preterm Labor and Preterm Premature Rupture of Membranes

Amniotic fluid Gram stain and culture have been utilized as laboratory tests of microbial invasion of the amniotic cavity. The Gram stain of amniotic fluid has a low sensitivity in the detection of clinical infection or microbial invasion of the amniotic cavity, and amniotic fluid culture results are not immediately available for management decisions. Glucose concentration is used to diagnose infection in other sites such as cerebrospinal fluid. Objective: The purpose of this study was to evaluate the usefulness of amniotic fluid glucose concentration in detecting microbial invasion of the amniotic cavity associated with preterm labor and preterm premature rupture of membranes. Methods: Amniocentesis was performed in 60 women with preterm labor and/or preterm premature rupture of membranes. Gram stain and culture for Mycoplasma hominis, Ureaplasma urealyticum, aerobic, and anaerobic bacteria were performed. Subjects were studied prospectively for the development of positive amniotic fluid cultures and the development of clinical chorioamnionitis. Results: The diagnosis of clinical chorioamnionitis was made in 25% (15/60) of women entered into the study. Low amniotic fluid glucose concentration Was considered < 15 mg/dl. The sensitivity, specificity, and positive predictive value of low amniotic, fluid glucose concentration to predict clinical chorioamnionitis were 73.3%, 88.1%, and 68.8% respectively, while positive amniotic fluid culture, hada sensitivity of 43.8%, specificity of 79.5%, and positive predictive value of 43.8%. Conclusions: Amniotic fluid glucose concentration was more sensitive in predicting chorioamnionitis than either Gram stain or culture. Amniotic fluid glucose concentration was better in predicting clinical chorioamnionitis than predicting positive amniotic fluid culture results. Gestational age-dependent normal ranges and pathologic conditions that may alter amniotic fluid glucose concentrations should be considered when interpreting amniotic fluid glucose values to diagnose microbial invasion of the amniotic cavity.