Augmentation of labor: does internal tocography result in better obstetric outcome than external tocography?

Labor was augmented in 250 patients for slow progress. These women were randomized to have uterine contractions recorded by either an external tocotransducer or an intrauterine catheter. Oxytocin was titrated to achieve an optimal frequency of contractions of six to seven every 15 minutes in each group; additional information on active contraction area profiles was available for those patients who had an intrauterine catheter. There was no statistically significant difference between the groups in the length of the post-augmentation period. The mean maximum dose of oxytocin was 11.1 mU/minute in the external tocography group and 11.0 mU/minute in the internal tocography group. Evidence of uterine hyperstimulation requiring temporary reduction of the oxytocin dose occurred in 19 and 20.2% of the patients in the external and internal tocography groups, respectively. Cesarean delivery was necessary in 12.6 and 16.9% of patients in the external and internal tocography groups, respectively, which is a nonsignificant difference. The incidence of low Apgar scores in the neonates and admission to neonatal intensive care was similar in both groups. The incidence of poor Apgar scores was not different between those who had transient hyperstimulation and those who had no hyperstimulation. In the management of augmented labor, monitoring of uterine contractions by intrauterine pressure catheters did not confer any advantage over tocography by external transducers.