The value of the leukocyte esterase test in diagnosing intra-amniotic infection

This communication examines the diagnostic value of the leukocyte esterase activity (LEA) test in the detection of intra-amniotic infection. Amniotic fluid from 171 consecutive patients with premature rupture of membranes (n = 149) and preterm labor (n = 22) was obtained through amniocentesis. Gram stain, bacterial and mycoplasma cultures, and LEA tests were performed. The LEA had a sensitivity of 19%, a specificity of 86.7%, a positive predictive value (PPV) of 42.3% and a negative predictive value (NPV) of 67.6% in the prediction of a positive amniotic fluid culture (prevalence of positive cultures = 33.9%). The Gram stain had a sensitivity of 36.2%, specificity of 94.7%, PPV of 77.8%, and NPV of 74.3%. When both tests were combined, a significant increase in sensitivity to 50% was observed. This was associated with a drop in specificity to 81.4%. There was a correlation between the number of white blood cells in the amniotic fluid and the result of the LEA test. A positive LEA assay was associated with an increased likelihood of postpartum endometritis, but not with clinical chorioamnionitis or neonatal infectious morbidity.