In view of the clinical paradigm shift "Six is the new Four", should the role of intrapartum hyoscine butyl bromide be reconsidered? A cohort study.

BACKGROUND

Hyoscine butyl bromide (HBB) inhibits the parasympathetic activity of the utero-cervical plexus with a potential to induce cervical dilatation by relaxing the cervical smooth muscles. However, many studies had administered HBB using an earlier threshold to define the onset of active labor.

OBJECTIVE

To determine the effect of HBB on the progress of labor, and the time taken for full dilatation, using the current recommended threshold of 5 cm dilatation of cervix to define the onset of active phase of labor.

MATERIAL AND

METHODS

100 patients (50 primigravidae and 50 multigravidae) who had received HBB after the cervical dilatation of 5 cm were compared with their respective control groups of 100 patients. The rate of progress of labor, the time taken to reach full dilatation and the proportion of women who exceeded the partogram expectation to reach full dilatation were analyzed in the study group (100 women) and these were compared to a control group (100 women) who did not receive HBB. The Mann-Whitney U Test and Fisher's Exact Test were used for statistical analysis.

RESULTS

In primigravidae, the median time to taken to achieve full dilatation was 6 h in women who did not receive HBB compared with 2 h in the HBB group (Mann-Whitney U Test p < 0.001). In multigravidae, the median time to taken to reach full dilatation was 6 h in women who did not receive HBB compared with only 2 h in the HBB (Mann-Whitney U Test p < 0.001). The proportion of women who exceeded the standard partogram expectation of 6 h to reach full dilatation was 38% and 2%, respectively in primigravidae (Fisher's Exact test p < 0.001), and 30% and 2%, respectively, in multigravidae (Fisher's Exact test p < 0.001). There was no statistically significant difference in the maternal and perinatal outcomes between the two groups.

CONCLUSION

Administration of HBB after redefining to the active phase of labor according to the contemporary scientific evidence and adjusting the rate of infusion based on to the cervical dilatation was associated with a statically significant reduction in the time taken to reach full dilatation of cervix.