Amniotic fluid infection as determined by transabdominal amniocentesis in patients with intact membranes in premature labor

The rate of microbial infection of amniotic fluid among patients in premature labor with intact membranes and the effect of this condition on perinatal morbidity and mortality are not known. To study this question, specimens of amniotic fluid were collected by transabdominal amniocentesis from 31 patients in premature labor with intact membranes. Microorganisms were isolated from 25% (8/31) of the specimens; 87% (7/8) of these mothers underwent delivery within 48 hours of amniocentesis, and 75% (6/8) of positive cultures were from mothers who never febrile. Perinatal morbidity was significantly greater among mothers with positive amniotic fluid cultures, as evidenced by earlier gestational age at delivery (31 vs. 36 weeks), lower newborn weight (1,704 vs. 2,613 grams), and longer hospitalization (39 vs. 9 days). A few simple, commonly available laboratory tests (amniotic fluid Gram stain, lactic dehydrogenase levels, and white blood cell count) appear to be useful in making a rapid diagnosis. The data suggest that the presence of microorganisms in the amniotic fluid of afebrile patients in premature labor with intact membranes represents an infectious process rather than an innocuous condition and raises questions with regard to current obstetric trends in the management of premature labor. The routine evaluation of similar patients by transabdominal amniocentesis is not recommended unless prospective studies can demonstrate a decrease in perinatal morbidity and mortality with this approach.