Interleukin-6 in amniotic fluid obtained at forewater amniotomy compared with hindwater samples in women in spontaneous labour

Using an aseptic technique, samples of amniotic fluid were obtained from the forewaters and hindwaters of fifteen women in spontaneous labour with a deeply engaged fetal head. Prior to sampling, a cervical swab was obtained to exclude infection and in 10 cases samples of amniotic fluid were sent for microscopy and culture. Forewater samples were obtained using a pudendal block needle. Hindwater samples were obtained after membrane rupture by inserting an intra-uterine pressure catheter. Batch assay for interleukin-6 (IL-6) concentrations was performed using a specific ELISA. The levels of IL-6 in forewater samples of amniotic fluid were significantly higher than those found in hindwater samples ( t = 3.65, P < 0.002). This suggests that either the production of IL-6 as a result of stimulation by its cytokine ‘effectors’ is greater at this site, or that the loss or metabolism of IL-6 in the forewaters is less than that in the hindwaters. The concentration of IL-6 parallels the reported levels of PGE 2, and it is therefore likely that if IL-6 is involved in the mechanism of labour it acts through the effects of the resultant PGE 2 release.