For Physicians. By Physicians.™

ObGFirst: Get guideline notifications, fast. First month free!Click here

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


  • 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

Learn More – Primary Sources:

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