Gram stain results from amniocentesis in patients with preterm premature rupture of membranes--comparison of maternal and fetal characteristics.

A total of 108 patients with preterm premature rupture of membranes who had undergone amniocentesis were retrospectively analyzed. Seventy-seven patients had negative amniotic fluid Gram stains and were managed expectantly. Thirty-one patients had positive amniotic fluid Gram stains confirmed by subsequent cultures and were delivered of infants on that basis. A univariate comparison of various parameters revealed significant differences in maternal temperature, pulse, and white blood cell count. Patients with positive Gram stains had lower mean gestational age, higher baseline fetal heart rate, and nonreactive fetal heart rate tracings. On the basis of a multivariate stepwise discriminate analysis, fetal heart rate greater than 150 beats/min or nonreactive nonstress test were the best predictors of the Gram stain findings, with a sensitivity of 71%, specificity of 76%, and negative predictive value of 87%. These data suggest that in patients with preterm premature rupture of membranes and fetal tachycardia or nonreactive nonstress test, amniocentesis should be performed in the initial evaluation.