Objective: This study was undertaken to examine whether oligohydramnios in women with preterm premature rupture of membranes is associated with evidence of fetal, amniotic, and maternal inflammatory responses.
Study design: Amniotic fluid index was measured before the performance of amniocentesis in patients with preterm premature rupture of membranes. Fifty-nine patients who were delivered of preterm neonates (gestational age </=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 was evaluated by the following: presence of clinical and histologic chorioamnionitis; amniotic fluid concentrations of interleukin 6, interleukin 1beta, and tumor necrosis factor alpha; amniotic fluid white blood cell count; and interleukin 6 concentrations in umbilical cord plasma at birth. Proinflammatory cytokines were measured with specific and sensitive immunoassays.
Results: Thirty-two percent (19/59) of patients had an amniotic fluid index </=5 cm. Patients with an amniotic fluid index </=5 cm had significantly higher rates of positive amniotic fluid culture results and clinical and histologic chorioamnionitis; higher median amniotic fluid concentrations of interleukin 6, interleukin 1beta, and tumor necrosis factor alpha; and higher median cord plasma concentrations of interleukin 6 than did those with an amniotic fluid index >5 cm (positive amniotic fluid culture result, 79% [15/19] vs 30% [12/40]; clinical chorioamnionitis, 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 amniotic fluid interleukin 1beta 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). There 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 membranes is associated with an inflammatory response in the fetal, amniotic, and maternal compartments.