Here is the design of a clinical trial:

Official Title: MEchanical DIlatation of the Cervix in a Scarred Uterus (MEDICS)

Included conditions:
- Pregnancy Related
- Labor Complication
- Cesarean Section; Dehiscence

Study Armgroups:
- {'label': 'Cervical Balloon', 'type': 'ACTIVE_COMPARATOR', 'description': 'Transcervical 2-way 18 French (18F) single balloon Foley catheter, applied using a sponge-holding forceps into the cervical canal with the balloon inflated to a minimum of 30ml and maximum of 60ml with sterile water or saline \\[1\\]. This will be administered once during the study and will be retained for a maximum of 12 hours within the 24 hour study period.', 'interventionNames': ['Device: Cervical balloon']}
- {'label': 'Prostaglandin', 'type': 'ACTIVE_COMPARATOR', 'description': 'Prostaglandin E2 (Prostin®) 3mg tablet, placed high in the vaginal fornix. This will be administered per vaginum once in the first 6 hours; a second dose is administered at the discretion of the clinician / clinical team 6 hours after the first pessary, for a cumulative total of 6mg within the 24 hour study period.', 'interventionNames': ['Drug: Prostaglandins']}

Interventions:
- {'type': 'DEVICE', 'name': 'Cervical balloon', 'description': 'To assess if a cervical balloon catheter (foleys catheter) for mechanical induction of labour is comparable to prostaglandin usage for induction of labour in women who have had a previous caesarean section.', 'armGroupLabels': ['Cervical Balloon'], 'otherNames': ['Foley Balloon Catheter']}
- {'type': 'DRUG', 'name': 'Prostaglandins', 'description': 'Prostin will be used in the control arm.', 'armGroupLabels': ['Prostaglandin'], 'otherNames': ['Prostin']}

Primary Outcomes:
- {'measure': 'Improvement in Bishops score', 'description': 'Assess for increase in Bishops score from baseline of \\<5 (Unfavourable) to \\>6', 'timeFrame': '24hours'}

Please estimate the sample size based on the assumption: 
Using α=0.05 and 80% power, with an anticipated attrition rate of 20%.
Statistical analysis plan and sample size estimation
        We deliver ~4000 pregnancies annually, of which 10%â15% are of patients with a single previous CS. Of these, ~60% attempt TOLAC (20 per month) and 20%â25% undergo IOL (5 per month). At our centre, the current VBAC success rate is ~40%â55%, with the remaining patients undergoing emergency CS. The variance applied to our population is derived from a retrospective cohort study from Hong Kong using the DBC in 24 women with one previous CS in which the median improvement in BS was 3 units with an IQR of 2.50 Assuming a normal distribution we derive a variability of Î´=1.5. Postulating that the difference in modified BS between the two groups at 12â24âhours is 1 point with a range of 2â8 points (SD=1.5),64 using Î±=0.05% and 80% power we calculate that we require 40 patients in each arm. Anticipating an attrition rate of 20%, a total of 100 subjects will be randomised equally into the two groups. A general linear model will be used to compare numerical outcome variables between both groups, while Poisson regression will be used to compare binary outcomes and derive relative estimates. All analyses will be performed using SPSS V.25.0 and GraphPad Prism V.6.07.