Drotaverine, Hyoscine, and Valethamate for Improving Bishop Score
Direct Answer
None of these antispasmodic agents (drotaverine, hyoscine butyl-bromide, or valethamate) are recommended for improving an unfavorable Bishop score, as they do not perform cervical ripening—instead, use dinoprostone or mechanical methods (Foley catheter) for cervical ripening when the Bishop score is <5. 1, 2
Understanding the Clinical Context
What These Drugs Actually Do
Antispasmodics (drotaverine, hyoscine, valethamate) reduce smooth muscle spasm and may accelerate cervical dilation during active labor, but they do not ripen an unfavorable cervix before labor begins. 3
The Bishop score <5 identifies an unfavorable cervix that requires cervical ripening before oxytocin or active labor management can be effective. 1, 4
Cervical ripening and labor augmentation are fundamentally different processes: ripening changes cervical structure (softening, effacement) while augmentation enhances uterine contractions during established labor. 1
Evidence on Antispasmodics in Labor
Efficacy During Active Labor (Not Cervical Ripening)
A 2012 Cochrane review found that antispasmodics (including valethamate, hyoscine, and drotaverine) reduced first stage labor duration by 66 minutes and increased cervical dilation rate by 0.55 cm/hour, but this was in women already in established labor, not for cervical ripening. 3
The evidence quality was low due to poor study design, significant heterogeneity, and inconsistent reporting of adverse events. 3
Comparative Studies Show Conflicting Results
A 2001 trial found drotaverine superior to valethamate (injection-to-delivery interval 194 vs 221 minutes), with fewer side effects, but both groups were already at 4 cm dilation in active labor. 5
A 2010 study confirmed drotaverine reduced injection-delivery time to 183 minutes versus 207 minutes for valethamate and 245 minutes for placebo, again in women already in active labor at 4 cm. 6
However, a 2008 trial found no significant difference between drotaverine and hyoscine versus controls for labor augmentation, with mean active phase durations of 4.5,3.9, and 3.6 hours respectively (not statistically significant). 7
A 2020 meta-analysis of hyoscine showed it reduced active labor phase by 84 minutes overall, but with 99% heterogeneity between studies, limiting confidence in the findings. 8
Correct Approach to Unfavorable Bishop Score
Step 1: Assess Cervical Favorability
Measure the Bishop score before induction; a score <5 mandates cervical ripening before oxytocin can work. 1, 4
A Bishop score ≥5 permits immediate oxytocin and amniotomy without prior ripening. 1
Step 2: Choose Appropriate Cervical Ripening Method
First-Line: Dinoprostone (Prostaglandin E₂)
Dinoprostone 10 mg vaginal insert (releasing 0.3 mg/hour) is indicated for cervical ripening in women with Bishop score <5, removed after 12 hours maximum or onset of active labor. 2
Wait at least 30 minutes after removing dinoprostone before starting oxytocin. 1
Continuous fetal heart rate and uterine activity monitoring are mandatory throughout dinoprostone use. 2
Alternative: Oral Misoprostol
Oral misoprostol 20-25 µg every 2-6 hours results in fewer cesarean sections (RR 0.84) and costs significantly less than dinoprostone. 1
Misoprostol is absolutely contraindicated in women with prior cesarean delivery due to 13% uterine rupture risk. 1
Alternative: Mechanical Methods (Foley Catheter)
Mechanical cervical ripening is preferred over prostaglandins in women with prior cesarean delivery or active cardiovascular disease. 1, 2
Administer pre-procedure NSAID (naproxen 500-550 mg or ibuprofen 800 mg) 1-2 hours before Foley insertion to reduce discomfort. 1
Critical Contraindications to Dinoprostone
Active cardiovascular disease is an absolute contraindication to dinoprostone due to marked blood pressure changes, potential coronary vasospasm, and arrhythmia risk. 2
Cyanotic heart disease contraindicates dinoprostone because it reduces systemic vascular resistance and worsens hemodynamics. 2
In these patients, use mechanical methods (Foley catheter) exclusively for cervical ripening. 2
When to Consider Antispasmodics (After Ripening)
Once cervical ripening is complete and active labor is established (typically ≥4 cm dilation with regular contractions), antispasmodics may be considered as adjuncts to accelerate labor, though evidence is mixed. 3, 5, 6
Drotaverine appears to have fewer side effects than valethamate (which causes maternal tachycardia, flushing, dry mouth), but neither drug addresses the fundamental problem of an unfavorable cervix. 5, 6
Hyoscine evidence is highly heterogeneous and unreliable for clinical decision-making. 8
Definition of Failed Induction
Allow at least 12 hours after completing cervical ripening, membrane rupture, and oxytocin use before declaring "failed induction" and proceeding to cesarean delivery. 1
Nulliparous women require longer induction times (often 24+ hours total) while multiparous women progress faster with dilation rates ≥1.5 cm/hour. 1
Common Pitfalls to Avoid
Do not use antispasmodics as a substitute for proper cervical ripening when Bishop score is <5—they will not soften or efface the cervix. 1, 3
Do not initiate oxytocin when Bishop score is <5 without first performing cervical ripening; oxytocin alone is ineffective in this setting. 1
Do not use dinoprostone in patients with active cardiovascular disease; switch to mechanical methods immediately. 2
Do not declare failed induction before the mandatory 12-hour observation period after ripening, membrane rupture, and adequate oxytocin titration. 1
Do not use misoprostol in women with prior cesarean section due to high uterine rupture risk. 1