Grand Rounds

How Does Dilapan-S Compare to Foley Balloon for Cervical Ripening?

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

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)

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)

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

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