Hyoscine Butylbromide for Cervical Rigidity in the First Stage of Labor: Randomized Clinical Trial

Background: Midwives and obstetricians may encounter dilations complicated by cervical rigidity, diagnosed during the periodic vaginal examinations performed during labor. Objective: To assess the effects of hyoscine butylbromide for cervical rigidity in the first stage of labor Study design: randomized, placebo-controlled, double-blind, parallel, pre-post clinical trial. Pregnant women delivering at University Hospital Germans Trias i Pujol in Badalona, Barcelona between January 2013 and January 2018 were eligible for inclusion. Our calculated sample size target was 70 participants 35 in each group with a 95% confidence level, an alfa and beta level of 5% and 80% power. The intervention group received 40 mg of hyoscine butylbromide intravenously, while controls received a placebo drip. Primary outcomes were: duration (minutes) of the first stage of labor, duration (minutes) from intervention to complete dilation and changes in cervical rigidity. We also collected data on maternal and neonatal variables. Results: Seventy-one women were included: 47 (66.2%) were nulliparous, and 35 (49.3%) had a spontaneous onset of labor. Fifty-seven (80.3%) women had vaginal deliveries: 37 (52.1%) were eutocic, 7 (9.8%) were assisted by obstetric vacuum, and 13 (18.3%) with forceps/spatulas; 14 (19.7%) were cesarean deliveries following complete dilation. Mean duration of the first stage of labor was 48.3 minutes shorter in the experimental group compared to the control (p=0.287), and mean time from intervention to complete dilation was 63.3 minutes shorter in the experimental group than control group (p=0.084). Conclusion: dilation time and duration of delivery were lower in women with cervical rigidity who receive hyoscine butylbromide, but differences were not statistically significant.