Tension compared to no tension on a Foley transcervical catheter for cervical ripening: a randomized controlled trial

BACKGROUND: Cervical ripening of an unfavorable cervix can be achieved by placement of a transcervical catheter. Advantages of this method include both lower cost and lower risk of tachysystole than other methods. Despite widespread use with varying degrees of applied tension, an unanswered question is whether there is an advantage to placing the transcervical catheter to tension compared with placement without tension. OBJECTIVE: The purpose of this study was to determine whether tension placed on a transcervical balloon catheter that is inserted for cervical ripening results in a faster time to delivery. STUDY DESIGN: This was a prospective, randomized controlled trial; 140 women who underwent cervical ripening (Bishop score, <= 6) were assigned randomly to a balloon catheter with applied tension vs no tension. Tension was created when the catheter was taped to the patient's thigh and tension was reapplied in 30-minute increments. There were 67 patients in the tension group and 73 patients in the no tension group. Lowdose oxytocin (maximum, 6 mU/min) was administered after catheter placement. The primary outcome was time from catheter insertion to delivery. A secondary outcome was time from insertion to catheter expulsion. The Kolmogorov-Smirnov test was used to determine whether the data were distributed normally. Survival curves that used lifetables were constructed from time of catheter insertion to delivery and from time of catheter insertion to catheter expulsion and were compared with the use of the Wilcoxon (Gehan) Breslow statistic. A probability value of <.05 was set to denote statistical significance. RESULTS: Baseline characteristics were similar between groups. The median time from catheter insertion to delivery was not significantly different between the tension group and the no tension group (16.2 vs 16.9 hours; P =.814). The median time from catheter insertion to expulsion, however, was significantly less in the tension group vs the no tension group (2.6 vs 4.6 hours; P <.001), respectively. Vaginal delivery within 24 hours was not significantly different between the tension and no tension groups (41/52 [ 79%] vs 37/52 [ 71%]; P =.365) nor were there significant differences in cesarean delivery rates between the tension and no tension groups (17/67 [ 25%] vs 27/73 [ 37%]; P =.139). CONCLUSION: Application of tension did not result in faster delivery times but did result in faster times to catheter expulsion.