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The Foley balloon is a tried and true mechanical method for cervical ripening
Dr. Esakoff is an Assistant Professor of Obstetrics and Gynecology in the Department of Obstetrics and Gynecology, Division of Maternal-Fetal Medicine at Cedars-Sinai Medical Center and the David Geffen School of Medicine at the University of California,
Dr. Kilpatrick is the Helping Hand of Los Angeles Endowed Chair Professor and Chair of the Department of Obstetrics and Gynecology at Cedars-Sinai Medical Center and Professor of Clinical Obstetrics and Gynecology at the David Geffen School of Medicine at the University of California, Los Angeles. She is also a member of the Contemporary OB/GYN editorial board. Neither author has a conflict of interest to disclose with respect to the content of this article.
Rates of labor induction in the United States rose from 9.5% to 23.2% of all deliveries between 1990 and 2010.1,2 Although labor is usually induced for maternal or fetal indications, inductions without maternal or fetal indication, or elective inductions, recently have been on the rise.3,4
Many women who undergo labor induction do not have a favorable cervix, so some method of cervical ripening-pharmaceutical or mechanical-often is used.5,6 Synthetic prostaglandins are thought to mimic the cervical ripening action of endogenous prostaglandins whereas synthetic oxytocin is thought to mimic the actions of natural oxytocin.
Mechanical methods, consisting of transcervical balloons and laminaria tents, are among the oldest ways to initiate labor and were developed to promote cervical ripening and onset of labor by stretching the cervix.
This paper reviews the role of the Foley transcervical balloon in cervical ripening and labor induction.
Illustration by Alex Baker, DNA Illustrations, Inc.
Clinically important endpoints for the study of cervical ripening or labor induction include labor length, cesarean delivery rates, and any adverse effects on the fetal heart rate (FHR).
Many studies have compared the transcervical Foley balloon to other methods of induction, but unfortunately, most have had small sample sizes and are therefore difficult to interpret.5
To improve sample size, a large systematic review grouped all mechanical methods together rather than evaluating transcervical Foley balloon catheters separately.6 That study summarized
3 systematic reviews that compared prostaglandins to mechanical methods such as laminaria tents, synthetic equivalents such as a Dilapan cervical dilator, transcervical Foley catheters, and other types of balloon catheters for induction of labor.
The researchers concluded that mechanical methods were less likely to result in uterine hyperstimulation than was prostaglandin E2 (PGE2) or vaginal misoprostol, but may be associated with increased maternal and neonatal infectious morbidity.6
A recent Cochrane review, however, examined various mechanical induction methods compared to the prostaglandins and oxytocin and specifically looked at a subgroup managed with transcervical Foley balloons.5 The key findings from that Cochrane review are described below and in Table 1.
Transcervical Foley balloon versus placebo
When comparing transcervical Foley balloon to placebo there was no difference in the incidence of cesarean delivery, but the transcervical Foley balloon did significantly increase the favorability of the cervix within 12 hours of treatment, with only 6% of women having an unfavorable cervix, compared to 86% in the no-treatment group.5,7,8
Transcervical Foley balloon versus prostaglandins
Twenty-three studies comparing the transcervical Foley balloon to any prostaglandin found no statistically significant difference in achieving a vaginal delivery within 24 hours or in the incidence of cesarean delivery.5
However, significantly less uterine tachysystole with FHR changes (ie, hyperstimulation) was seen in the transcervical Foley balloon group compared to the prostaglandin group (relative risk [RR] 0.19, 95% confidence interval [CI], 0.08–0.43).
Serious maternal morbidity and neonatal morbidity were rare events and did not differ between the groups. Oxytocin use was more common during labor in women who had started out with transcervical Foley balloons than in those who started with prostaglandins (RR 1.51, 95% CI, 1.15–1.97).5
Transcervical Foley balloon versus oxytocin
Finally, in a comparison of the transcervical Foley balloon with oxytocin, risk of cesarean delivery was significantly reduced in the balloon group (RR 0.57, 95% CI, 0.38–0.88) but no difference was seen in maternal/neonatal morbidity or hyperstimulation.5
Transcervical Foley balloon combinations
Trancervical Foley balloon with prostaglandins versus prostaglandins alone
Transcervical Foley balloons have also been used in combination with prostaglandins. In one study, the combination was associated with a significantly increased likelihood of a vaginal delivery within 24 hours (55%) with no impact on the cesarean delivery rate (31% vs 33%).
Uterine hyperstimulation was less common in the combined group (RR 0.53, 95% CI, 0.35–0.78) but both groups had relatively high rates of hyperstimulation at 12% versus 26%.
Transcevical Foley balloon with oxytocin versus prostaglandins alone
The combination of transcervical Foley balloon and oxytocin versus prostaglandin alone did not result in any differences in outcomes.5
Most recently, a retrospective cohort study of misoprostol versus the transcervical Foley balloon plus oxytocin found similar total duration of labor but differences in the labor curves between the 2 groups. Women in the balloon-plus-oxytocin group had faster progression of cervical dilation from 1 cm to 4 cm but a slower progression from 4 cm to 10 cm compared to the misoprostol group.
Transition from latent to active phase occurred at 4 cm for the misoprostol group and at 6 cm for the balloon-plus-oxytocin group.9
In summary, it appears that transcervical Foley balloons are as effective as prostaglandins in achieving vaginal delivery within 24 hours and have the benefit of causing less hyperstimulation compared to prostaglandins. They are also associated with a lower cesarean delivery rate than oxytocin use alone.
The effect on the labor curve of use of a transcervical Foley balloon should be considered in management of labor.
A transcervical Foley balloon can be inserted either digitally during a vaginal examination or using direct visualization by sterile speculum exam. No data exist to support one method over the other.
Although it is also unclear if the aseptic technique makes a difference, we use that technique in our practice. Typically, a 16F transcervical Foley catheter balloon is advanced to or past the internal os and the balloon is filled with 30 mL–80 mL of sterile water. The catheter is then placed on gentle traction by taping the distal tip to the medial thigh. To maintain gentle traction, periodic repositioning of the distal tip on the thigh is necessary. This is supported by a recent comparison of simple taping to the thigh versus keeping the balloon on tension, which found that although total time to delivery did not differ for the 2 methods, time to spontaneous catheter expulsion was significantly shorter in the traction group (2.6 hrs vs 1.5 hrs, P <0.001).10
Transcervical Foley balloons are thought to be safe and cost-effective methods of cervical ripening.5,6,11
A recent study of more than 1000 women found that complications were rare with transcervical Foley balloons but included the following: acute transient febrile reaction (3%), non-reassuring FHR tracing (2%), vaginal bleeding (1.8%), pain necessitating removal of catheter (1.7%), and altered fetal presentation from vertex to breech (1.3%).12
One of the theoretical concerns about transcervical balloons is the risk of infection. Few studies have addressed this issue and those that have are quite small. Nevertheless, the risk of puerperal and neonatal infection based on the current evidence does not appear to be higher with mechanical methods such as the Foley balloon than with other methods of induction.13-15
Multiple types of balloon catheters for cervical ripening have been investigated (Table 2). In a comparison of the standard transcervical Foley balloon catheter with extra-amniotic saline infusion with the Cook cervical ripening balloon (a double balloon catheter), time from insertion to delivery was shorter (19.6 hrs vs 23.4 hrs, P = 0.03) and the cost was less for the standard than the Cook balloon.16
Another study compared single transcervical Foley balloon catheters without extra-amniotic saline infusion to double balloon catheters. The single balloon catheter resulted in a significantly shorter induction-to-delivery interval (median time 23.2 hrs [95% CI, 20.8–25.8] vs 24.5 hrs [95% CI, 23.7–30.6]) and significantly less pain for the patients (pain score ≥4 in 36% for the single balloon vs 55% for the double balloon, P< 0.001).17
Data are mixed on whether extra-amniotic saline infusion in conjunction with a transcervical Foley balloon is beneficial and if there is associated risk. A retrospective study from a single tertiary care hospital found increased risk of chorioamnionitis with extra-amniotic saline infusion compared to other methods of induction.18
In contrast, a randomized controlled trial of the Foley catheter with concurrent oxytocin infusion versus Foley catheter with extra-amniotic saline infusion with concurrent oxytocin infusion found no difference in complications between the 2 groups. However, no increased efficacy was seen with extra-amniotic saline infusion.20
Finally, another randomized trial comparing transcervical Foley balloon with and without extra-amniotic saline infusion reported a shorter induction-to-vaginal delivery time and decreased incidence of chorioamnionitis with extra-amniotic saline infusion.20
Several studies have also evaluated whether the amount of inflation of the transcervical Foley balloon affects outcome. The first study compared a 30-mL Foley balloon with an 80-mL Foley balloon for preinduction cervical ripening and found that the 80-mL balloon provided significantly more dilation, faster labor, and decreased need for oxytocin.21
The second study compared a 30-ml balloon with a 60-mL balloon and found that the 60-mL balloon was more likely to result in delivery within 12 hours. No differences were seen in rates of delivery within 24 hours, cesarean delivery, or labor complications, or neonatal outcomes.22
In summary, the standard single transcervical Foley balloon is more efficacious and less expensive than the Cook balloon. Data are mixed on whether higher dilation of the balloon provides improved long-term benefit in labor induction.
Evidence suggests that transcervical Foley balloons may have a role in the outpatient setting. A randomized trial of 111 women at term using the transcervical Foley balloon for preinduction cervical ripening in an outpatient versus an inpatient setting found it to be just as effective in the outpatient setting, with no increase in maternal morbidity or any adverse events.23
Specifically, the researchers found that the mean change in Bishop scores after catheter placement did not differ between the inpatient and outpatient groups, and the maximum dose of oxytocin, time of oxytocin, epidural rate, induction time, 1- and 5-minute Apgar scores, and cord pH were not significantly different. No adverse events or maternal morbidity were reported in either group.23
However, this study was underpowered for these outcomes and more research is necessary on use of the Foley balloon for labor induction in the outpatient setting.
Although many providers use transcervical Foley balloons in the setting of a scarred uterus, data on this topic are limited.
A recent retrospective cohort study from France evaluated the safety and efficacy of balloon catheters for labor induction in 151 women with previous cesarean deliveries and reported a 54% rate of vaginal delivery and a 1.2% uterine rupture rate. The side effect profile was low.24
The researchers concluded that prior cesarean delivery is not an absolute contraindication for cervical ripening with the transcervical Foley balloon, but further studies are warranted.
Data are sparse on patient satisfaction with use of a transcervical Foley balloon for labor induction.
The only study evaluating the outcome of patient discomfort with insertion and cervical ripening using a visual analogue scale found significantly less discomfort during ripening with a single balloon catheter than with prostaglandins and a double balloon catheter.17
The transcervical Foley balloon is one of the least expensive methods for cervical ripening. Table 3 compares the wholesale cost of the transcervical Foley balloon to other commonly used methods. These prices do not reflect the cost of the entire induction or hospital mark-up.
The transcervical Foley balloon has been in use for many decades and is as effective as prostaglandins. It appears to be associated with fewer complications. It is clearly one of the least expensive methods available for labor induction.
The transcervical Foley balloon should be considered a useful tool for cervical ripening and induction of labor.
To download a PDF of this patient education handout, go to www.contemporaryobgyn.net/Foley_balloon.pdf
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