Placing tension on a transcervical balloon catheter reduces the time to catheter expulsion but does not hasten time to delivery, according to the results of a recently published randomized controlled clinical trial.1
The single-center prospective study was conducted at St. Mary’s Hospital, Saint Louis University School of Medicine, St Louis, Missouri. It included 140 women with a Bishop score ≤6 and a singleton cephalic gestation who had a balloon catheter (18 French 30 cc Foley bulb) placed with or without tension. Median time from catheter insertion to delivery was analyzed in an intent-to-treat population as the primary outcome, and it was not significantly different between the tension and no tension groups (16.2 hours vs 16.9 hours; P=.814).
Time from catheter insertion to expulsion, which was analyzed as a secondary outcome, was significantly shorter among women who had tension applied to the catheter compared with the no tension group (2.6 hours vs 4.6 hours; P<.001). The results for these 2 endpoints were similar in a per protocol analysis. Other analyses found no significant differences between the tension and no tension groups in the rate of vaginal delivery within 24 hours (79% vs 71%; P=.365) or cesarean delivery rate (25% vs 37%; P=.139].
There were very few complications. The rate of chorioamnionitis was 10.7% overall and not significantly different between the 2 study groups.
“We recognize that practitioners have limited tools with which to work when dealing with an unripe cervix, especially when medical ripening is either not indicated or unsuccessful. Thus, we are continuously evaluating our practice, and when assessing best practice with Foley mechanical dilation, we realized that the fundamental question of whether application of tension compared to no tension provides any advantages had never been evaluated,” said Gary Fruhman, MD.
“We feel that the findings of our study showing that tension placed on the catheter did not shorten delivery times will assist practitioners in simplifying the Foley bulb process. At our institution, we are no longer employing tension when using the transcervical balloon catheter.”
The study was completed while Dr Fruhman was a fellow in Maternal Fetal Medicine at Saint Louis University School of Medicine. He is now assistant director, Obstetrics and Maternal Fetal Medicine, Staten Island University Hospital, Staten Island, New York.
The women enrolled in the study were specifically selected to receive the transcervical catheter for cervical ripening versus other methods. Women were excluded from study participation if they had a medical condition precluding vaginal delivery, chorioamnionitis, vaginal bleeding, intrauterine fetal demise, a low-lying placenta, prior cervical surgery, or latex allergy. There were no statistically significant differences between the tension and no tension study groups in baseline maternal characteristics, including use of a prior cervical ripening agent.
As per the center’s protocol, the balloon was filled with 50 cc saline. In the tension group, the catheter was taped to the thigh with tension that was reapplied every 30 minutes as needed. After catheter placement, all women received low dose oxytocin with titration to a maximum of 6 milliunits/minute). The balloon was deflated and removed after 12 hours if it had not been expelled.
Dr Fruhman noted that the significant reduction in time to catheter expulsion in the tension group was an interesting finding.
“Considering that most patients were given an epidural injection after the catheter was removed, faster expulsion time with tension could result in less pain for patients,” he explained, “and therefore some practitioners may still want to apply tension even though the time to delivery is not decreased.”
Compared with the tension group, the no tension group received less oxytocin and had a significantly lower rate of epidural use (89.0% vs 98.5%; P=.035). The authors noted, however that the latter finding may be attributable to type II error of multiple comparisons. Median highest pain score during the time the catheter was in place was the same (7/10) in the two study groups.
The strength of the study lies in its prospective, randomized design. A potential limitation is that the amount of tension placed was probably not uniform among patients, Dr Fruhman told Contemporary OB/GYN.
1.Fruhman G, Gavard JA, Amon E, et al. Tension compared to no tension on a Foley transcervical catheter for cervical ripening: A randomized controlled trial. Am J Obstet Gynecol. 2016 Sep 15. [Epub ahead of print]