A comparative study of amniotic fluid white blood cell count and amniotic fluid culture for the prenatal diagnosis of intrauterine infection and the prediction of perinatal outcomes in women with preterm labor and intact membranes

Lee, Ki Joo; Kang, Sok Bom; Kim, Gil Ja; Kim, Teresa; Park, Joong Shin; Jun, Jong Kwan; Yoon, Bo Hyun; Syn, Hee Chul

Abstract

OBJECTIVES
To compare the diagnostic and prognostic performance of amniotic fluid white blood cell(AF WBC) count and amniotic fluid culture for the prenatal diagnosis of intrauterine infection and the prediction of neonatal outcomes in patients with preterm labor and intact membranes. Methods: Amniocentesis was performed in 75 patients with preterm labor and intact membranes, who delivered preterm neonates within 72 hours after amniocentesis. AF WBC was determined and amniotic fluid was cultured for aerobic and anaerobic bacteria as well as mycoplasma. The relations among placental histologic findings, perinatal outcome, AF WBC count, and AF culture were examined. Student t test, Mann Whitney U test, lamda2 test, Fisher's exact test, modified t test, and logistic regression analysis were used for statistical analysis. RESULTS: Microbial invasion of the amniotic fluid was more frequent in the patients with histologic chorioamnionitis than patients without histologic chorioamnionitis (28.9% vs 5.4%, p<0.05), and patients with histologic chorioamnionitis had significantly higher amniotic fluid white blood cell counts than those patients without such lesion (median 99, range 0-3024 cells/mm3 vs median 1, range 0-180 cells/mm3, p<0.01). Amniotic fluid white blood cell count (> or = 50cell/mm3) had a sensitivity of 55.3%(21/38) and a specificity of 94.6%(35/37) for the diagnosis of histologic chorioamnionitis and a sensitivity of 47.5%(19/40) and specificity of 90.9%(30/33) for the prediction of significant neonatal morbidity (defined as neonatal sepsis, respiratory distress syndrome, pneumonia, intraventricular hemorrhage, bronchopulmonary dysplasia, or necrotizing enterocolitis). These sensitivities were significantly higher than those of amniotic fluid culture (for histologic chorioamnionitis, 55.3% vs 28.9% ; for significant neonatal morbidity, 47.5% vs 25.0%, p<0.01 for each). CONCLUSION: Amniotic fluid WBC count is a more sensitive test for the prenatal diagnosis of intrauterine infection and for the prediction of significant neonatal morbidity than amniotic fluid culture in the patients with preterm labor and intact membranes.