Association of oligohydramnios in women with preterm premature rupture of membranes with an inflammatory response in fetal, amniotic, and maternal compartments

OBJECTIVE: This study was undertaken to examine whether oligohydramnios in women with preterm premature rupture of membranes is associated With eviden ce of fetal, amniotic, and maternal inflammatory responses. STUDY DESIGN: Amniotic fluid index was measured before the performance of a mniocentesis in patients with preterm premature rupture of membranes. Fifty -nine patients who were delivered of preterm neonates (gestational age less than or equal to 35 weeks) within 3 days of amniocentesis were included in this study. Amniotic fluid was cultured for aerobic and anaerobic bacteria and for genital mycoplasmas. The intensity of the inflammatory response wa s evaluated by the following: presence of clinical and histologic chorioamn ionitis; amniotic fluid concentrations of interleukin 6, interleukin 1 beta , and tumor necrosis factor alpha; amniotic fluid white blood cell count; a nd interleukin 6 concentrations in umbilical cord plasma at birth. Proinfla mmatory cytokines were measured with specific and sensitive immunoassays. RESULTS: Thirty-two percent (19/59) of patients had an amniotic fluid index less than or equal to 5 cm. Patients with an amniotic fluid index less tha n or equal to 5 cm had significantly higher rates of positive amniotic flui d culture results and clinical and histologic chorioamnionitis; higher medi an amniotic fluid concentrations of interleukin 6, interleukin 1 beta, and tumor necrosis factor a; and higher median cord plasma concentrations of in terleukin 6 than did those with an amniotic fluid index >5 cm (positive amn iotic fluid culture result, 79% [15/19] vs 30% [12/40]; clinical chorioamni onitis, 37% [7/19] vs 5% [2/40]; histologic chorioamnionitis, 100% [17/17] vs 69% [24/35]; median amniotic fluid interleukin 6 concentration, 13.5 ng/ mL; range, 0.2-142.2 ng/mL vs 3.0 ng/mL and 0.001-115.2 ng/mL; median amnio tic fluid interleukin 1 beta concentration. 348.0 pg/mL; range, 0.7->80,000 pg/mL vs 36.6 pg/mL and 0-2075 pg/mL; median amniotic fluid tumor necrosis factor alpha concentration, 132.0 pg/mL; range, 0-1600 pg/mL vs 11.2 pg/mL and 0-1305 pg/mL; median cord plasma interleukin 6 concentration, 49.7 pg/ mL; range, 4.4-7400 pg/mL vs 9.1 pg/mL and 0-5211 pg/mL; P<.05 for each). T here was no significant difference between the 2 groups of patients in the mean umbilical artery pH at birth. CONCLUSION: Oligohydramnios in women with preterm premature rupture of memb ranes is associated with an inflammatory response in the fetal, amniotic, a nd maternal compartments.