Amniotic fluid interleukin-6 and tumor necrosis factor-alpha at mid-trimester genetic amniocentesis: relationship to intra-amniotic microbial invasion and preterm delivery.

Objective: To determine the value of amniotic fluid interleukin-6 (AF IL-6) and tumor necrosis factor-alpha (AF TNF-alpha) in the diagnosis of microbial invasion of the amniotic cavity and in the prediction of preterm delivery (PTD).

Study Design: Following amniocentesis, a sample of amniotic fluid was sent for aerobic and anaerobic bacterial cultures along with Ureaplasma urealyticum culture and it was also assessed for IL-6 and TNF-alpha.

Results: Forty-eight women who delivered preterm (<37 weeks) were matched with 96 controls. The AF IL-6 and TNF-alpha concentrations of women with spontaneous PTD were significantly higher than those who delivered at term (IL-6: 176.3 pg/ml [130.6-208.6] vs. 52.3 pg/ml [37.2-92.3]; TNF-alpha: 8.8 pg/ml [7.2-10.7] vs. 5.5 pg/ml [5.0-6.3]). AF IL-6 and TNF-alpha concentrations of >99.3 pg/ml and of >6.6 pg/ml respectively, had a sensitivity of 89.6% and 81.3% and a specificity of 80.3% and 79.2% for the prediction of spontaneous PTD. Moreover, AF IL-6 and TNF-alpha concentrations of >99.3 pg/ml and of 6.3 pg/ml respectively, had a sensitivity of 91.9% and 78.4% and a specificity of 73.8% and 70.1% for the prediction of a positive AF culture.

Conclusions: Elevated mid-trimester concentrations of AF IL-6, or/and of TNF-alpha can identify women at risk for intra-amniotic infection and for spontaneous PTD.