BACKGROUND AND PURPOSE:

• Foley balloon is a common mechanical method for cervical ripening
• Dilapan-S is another mechanical cervical dilator
  • Approved for cervical ripening in the 3rd trimester (FDA 2015)
  • Hydrogel rods which absorb fluid, soften cells via reversible dehydration and volume expand within the cervical canal
• Saad et al. (AJOG, 2019) sought to compare Dilapan-S to Foley balloon for preinduction cervical ripening at term

METHODS:

• Randomized controlled trial (RCT) for noninferiority (DILAFOL study)
  • Pregnant women ≥37w0d scheduled for induction
  • Unfavorable cervix: ≤3 cm dilated and ≤60% effaced
  • Exclusion: Macrosomia | PROM | Chorio | Prior uterine scar | Active bleeding | Nonreassuring tracing | Requires immediate delivery
• Women were randomly assigned to 12 hours of either
  • Foley balloon inflated with 60 mL saline
  • Dilapan-S for cervical ripening (as many rods as possible under direct visualization)
• Dilapan-S left in place 12 to 24 hours | Foley left in place minimum 12 hours
• If cervix unripe after 2 attempts, pharmacological ripening undertaken
• If cervix ripe – oxytocin protocol started
• Patients were followed in the hospital setting, but could ambulate, shower and ‘perform regular activity’
• Primary outcome: Vaginal delivery
• Secondary outcomes included
  • Change in Bishop score | Operative vaginal delivery | Cesarean Section | Time to active stage | Induction to delivery time | Device placement to delivery time | Hospital stay | Total time device in place | Regional anesthesia | Analgesia during cervical ripening | Patient satisfaction
• Statistical analysis
  • Noninferiority trial to test if Dilapan-S is no worse than Foley by more than 10% (noninferiority margin)

RESULTS:

• 209 in Foley group | 210 in Dilapan-S group
• Vaginal delivery was more common in Dilapan-S (81.3%) vs Foley balloon (76.1%) in the intent to treat group
  • Absolute difference compared to Foley was 5.2% (95% confidence interval, –2.7% to 13.0%), above the 10% margin, therefore indicating noninferiority for the prespecified margin
  • The difference was not large enough to show superiority
• Similar findings obtained in the ‘per-protocol’ population
• There were no significant differences seen in the secondary outcomes
• Secondary outcomes
  • Dilapan-S remained longer in-situ than Foley
  • No other differences in secondary outcomes was noted, including maternal or neonatal adverse events
• Cervical dilation at randomization, parity, or BMI >30 did not impact vaginal delivery outcome
• There were significant differences in patient satisfaction
  • Patients with Dilapan-S were more satisfied than patients with the Foley balloon for the following
    • Sleep (P = .01)
    • Relaxing time (P = .001)
    • Performance of desired daily activities (P = .001)

CONCLUSION:

• Dilapan-S is not inferior to the Foley balloon for perinduction cervical ripening at term
• The authors point out Dilapan-S advantages
  • FDA approval
  • Safety profile
  • No protrusion from the introitus
  • No need to keep under tension
  • Higher patient satisfaction score

Learn More – Primary Sources:

A randomized controlled trial of Dilapan-S vs Foley balloon for preinduction cervical ripening (DILAFOL trial)

Related ObG Topics:

The FIAT-M study: Simultaneous or Sequential Foley and Oxytocin for Induction in Multiparous Women

What is the Best Labor Induction Method for Multiparous Women?

Single or Multi-Dose Misoprostol for Labor Induction?

The ARRIVE Trial and SMFM Guidance: Elective 39 Week Induction to Reduce the Risk of Cesarean Section