The relaxant effect of adrenergic compounds on isolated gravid human myometrium

The frequency and clinical significance of intra-amniotic inflammation in women with preterm uterine contractility but without cervical change: do the diagnostic criteria for preterm labor need to be changed?

OBJECTIVE

The objective of this study was to determine the frequency and clinical significance of intra-amniotic inflammation in patients with preterm increased uterine contractility with intact membranes but without cervical change.

METHODS

Amniocentesis was performed in 132 patients with regular uterine contractions and intact membranes without cervical change. Amniotic fluid was cultured for bacteria and mycoplasmas and assayed for matrix metalloproteinase-8 (MMP-8). Intra-amniotic inflammation was defined as an elevated amniotic fluid MMP-8 concentration (>23 ng/mL).

RESULTS

(1) Intra-amniotic inflammation was present in 12.1% (16/132); (2) Culture-proven intra-amniotic infection was diagnosed in 3% (4/132) of patients without demonstrable cervical change on admission or during the period of observation; and (3) Patients with intra-amniotic inflammation had significantly higher rates of preterm delivery and adverse outcomes, and shorter amniocentesis-to-delivery intervals than those without intra-amniotic inflammation (P < 0.05 for each). Adverse outcomes included chorioamnionitis, funisitis, and neonatal death.

CONCLUSION

Intra-amniotic inflammation was present in 12% of patients with regular uterine contractions without cervical change, while culture-proven intra-amniotic infection was present in 3%. The presence of intra-amniotic inflammation was a significant risk factor for adverse neonatal outcomes. These observations question whether cervical changes should be required for the diagnosis of preterm labor, because patients without modifications in cervical status on admission or during a period of observation are at risk for adverse pregnancy outcomes.

Beta-adrenoceptors in the pregnant and non-pregnant myometrium of the goat and cow

The muscle relaxing effect of beta-adrenoceptor agonists was examined without and with the presence of beta-adrenoceptor antagonists in strips from the pregnant and non-pregnant myometrium of the goat and from the pregnant myometrium of the cow. Isoprenaline, salbutamol and ritodrine caused a dose-dependent reduction of the spontaneous contractions of the pregnant myometrium and a dose-related and parallel shift to the right of the isoprenaline dose-response curve was obtained with butoxamine but not with practolol. Isoprenaline but neither salbutamol nor ritodrine caused a dose-related reduction of the spontaneous contractions in the non-pregnant myometrium and a dose-related and parallel shift to the right of the dose-response curve of isoprenaline was brought about with propranolol but not with either butoxamine or practolol. The muscle relaxing effect of ritodrine on the pregnant myometrium of the goat and cow shown in vitro was also demonstrated in vivo in the same species within eight hours of delivery. It is concluded that the beta-adrenoceptors in the pregnant myometrium of the goat and cow belong to the beta2-group whereas those in the non-pregnant myometrium cannot be classified as either beta1- or beta2-adrenoceptors.