Induction of Labor With a Foley Balloon Catheter: Inflation With 30ml Compared to 60ml

Overview

The rate of labor induction is rising throughout the United States for a variety of reasons. Medical conditions that lead to increased risk of prolonging the pregnancy to both mother and fetus are not infrequent. In addition, elective deliveries are becoming more common. Foley balloon catheter placement is a common method used for labor induction in women with an unfavorable cervical assessment. There are several studies using various volumes of Foley balloon catheters for labor induction ranging from 30ml to 80ml, however, there are no studies replicating the findings of the largest study comparing 2 different volumes in the balloon. The investigators plan to compare instillation of 30ml of sterile saline versus 60ml in a Foley balloon catheter for women undergoing induction of labor with an unfavorable cervix. The investigators will observe the following outcomes: rate of delivery within 24 hours, cervical dilation after foley balloon catheter expulsion, insertion to balloon expulsion interval, induction to delivery time interval, peak oxytocin requirement, presence of infection or meconium, cesarean delivery rate, operative vaginal delivery rate, indication for operative vaginal or cesarean delivery, cervical laceration rate, placental abruption rate, 5-minute Apgar score, and umbilical cord arterial blood pH and base excess.

All potential candidates will be approached for the study and undergo written consent if willing to participate. Each candidate will be randomized to 30ml or 60 ml Foley balloon catheter volume. A random number generator will be used and within a sealed envelope will be placed the assignment. Nulliparous and multiparous patients will be randomized separately. The patient will be positioned for a standard cervical exam - either for digital or speculum exam, depending on the individual patient preference and provider choice. For digital exam, a sterile Foley balloon catheter will be digitally placed in the endocervical canal, into the extraamniotic space (between the fetal head, external to the unruptured amniotic sac, above the internal os of the cervix). For speculum exam, the cervix is wiped three times with a Betadine cleansing solution, and a sterile Foley balloon catheter bulb will be placed under direct visualization into the endocervical canal, into the extraamniotic space. Once the balloon is in place the provider inserts 30ml of sterile saline. The provider then leaves the room. The patient's nurse opens the envelope and if the patient is allocated to the 60ml volume group, the nurse adds an additional 30ml of sterile saline. If the patient is in the 30ml group, the RN staff will simulate placement of additional saline into the foley balloon without actually placing any additional saline in order to also blind the patients to their assigned group. The MD/CNM providers will then return to the room, blinded to the inflation of the Foley balloon, and the balloon catheter will be placed under tension by taping the external end to the patient's inner thigh. Oxytocin will be started within 30 minutes of the Foley balloon catheter placement, using the standard intravenous oxytocin protocol. Additional manual traction on the Foley balloon catheter will be performed every 30 minutes until Foley balloon catheter expulsion. A sterile cervical exam will be performed after spontaneous Foley catheter expulsion to evaluate post-balloon cervical dilation. No further procedures or tests specific to this study will be required beyond this point; only data collection on the above study outcomes during the remaining course of the patient's labor will be recorded.