Grand Rounds

RCT Results: Does Adding a Weight to the Foley Used for Induction of Labor Improve Outcomes?

BACKGROUND AND PURPOSE:

Cherian et al. (International Journal of Gynecology and Obstetrics. 2022) assessed the effectiveness of attaching a weight to a Foley catheter for labor induction

Randomized controlled trial
Participants
- ≥39 weeks | Singleton live fetus | Cephalic
- Admitted for induction of labor with an unfavorable cervix
Interventions
- 30 ml Foley catheter
- 30 ml Foley with a 500 ml weight
Study design
- Foley filled with 30 ml of saline
- Weight: 500 ml of saline attached to the end of the Foley and hung over the edge of the bed
- AROM and oxytocin 12 hours after Foley insertion
- If Foley expelled <12 hours and not in active labor: AROM done 12 hours after Foley insertion and oxytocin started
Sample size calculation
- 80% power
- Reduction of cesarean section for failed induction from 20% to 10% with the use of Foley with weight
- Two-sided test (α error 5%)
- 199 participants required in each arm
Primary outcome
- Prevention of lower segment cesarean section for failed induction

Foley: 200 women | Foley with weight: 199 women
There was no difference in proportion of mode of delivery between groups
- Foley: 17.1%
- With wight: 17.5%
- 95% CI, 0.98 (0.63 to 1.49); P=0.913
There was no statistically significant difference in cesarean section rates for failed induction between groups
- Foley: 26.5%
- Foley with weight: 45.7%
- P=0.1
There was a shorter time to Foley expulsion with weight attachment
- Foley: 10.9 ± 3.2 hours
- Foley with weight: 2.6 ± 3.3 hours
- P<0.001
Shorter time to expulsion did not translate to a difference in
- Time to active labor
- Time to delivery
- Difference in number of women who attained a Bishop score of ≥6

The addition of a weight to the Foley catheter did not reduce the rate of cesarean delivery due to failed induction
The authors state that

… the added effort of placing a weight and the restriction of the woman’s movement seem unwarranted

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