Cervical Ripening With a Double-lumen Balloon Catheter for Six Versus Twelve Hours

The Foley catheter is a safe, effective method for cervical ripening. Limited data exists to indicate ideal time of placement for optimal cervical ripening prior to induction. The proposed study is a randomized control trial to determine if shortening placement from 12 to 6 hours of foley catheter can decrease time from start of induction to delivery. The prediction is that shortening foley bulb placement will result in shorter induction times, increased patient satisfaction and decreased length of stay on labor and delivery with secondary decreased medical costs.

Objective: To determine whether a double-lumen balloon catheter requires twelve hours in the cervical canal to achieve its maximal cervical dilation. It is the hypothesis that the maximum cervical dilation and benefits of a double lumen foley catheter are achieved within the initial six hours after placement.

Study Design:

Overview: All eligible patients with a singleton pregnancy at 37 weeks gestational age or greater who are presenting for a clinically/ medically indicated induction with an unfavorable cervical exam will be invited to participate. As per the American College of Obstetricians and Gynecologists (ACOG) guidelines, all inductions performed prior to 39 weeks are medically indicated. Medical indications for induction prior to 39 weeks include but are not limited to preeclampsia, oligohydramnios and growth restriction. Upon admission to Labor and Delivery, women will be assessed for eligibility by an obstetric physician. A digital cervical examination will be performed and a Bishop score assigned. Patients with a Bishop score ≤ 6 are thought to benefit from a cervical ripening agent and the participants will be randomized based on parity at this point.

Type of Study: This study will be a prospective, randomized clinical control trial with human subjects.

Materials and Methods:

A qualified obstetric provider will provide eligible women with details of the study, including study objectives and methods. Consent will be obtained and witnessed from patients who elect to participate. Enrollment and randomization in the study will then occur. Patients will be randomized to the two groups using computer generated random numbers. The randomization will be stratified based on parity (i.e., women who have had any prior vaginal delivery above 20 weeks gestation v. women who have not). A foley bulb will then be placed by a qualified obstetric provider. Foley bulb will be inserted with or without speculum technique and with or without use of a stylet. In accordance with the standard of care, sterile saline will be placed in the intrauterine and vaginal balloon as tolerated by the patient for no more than a maximum of 80 cc in each balloon. The use of concomitant low dose pitocin with the foley bulb will be at the discretion of the admitting obstetric team. If the patient's foley bulb does not spontaneously expel within the maximum allotted time, they will be manually removed at six or twelve hours. At the time of manual removal or expulsion of the foley balloon, the patient's cervix will be checked by an experienced obstetric provider. As per usual protocol, additional cervical ripening and labor induction will proceed per managing obstetric team.

Independent Variables:

Data collection will include the independent variables of maternal age, parity, BMI, race (Caucasian, African American, Hispanic, Asian, other), Bishop Score, use of magnesium and epidural use. Data collection of independent fetal variables will include gestational age and estimated fetal weight.

Outcome Variables:

The primary outcome will be time from foley bulb placement to time of delivery. Secondary outcomes will include time from foley bulb placement to extrusion and rate of cesarean section. Additional comparison variables include: neonatal weight, APGAR scores and intrapartum and postpartum infection rates.

Eligibility Criteria:
Inclusion Criteria:

1. Intrauterine pregnancy at 37 weeks gestational age or greater as determined by best obstetrical dating criteria
2. Singleton gestation
3. Vertex presentation
4. Clinically adequate pelvis
5. Bishop Score less than or equal to 6
6. 16 years and older

   * North Carolina state law provides for the emancipation of minors, Chapter 7B-Article 35.

Exclusion Criteria:

1. Any maternal or fetal contraindication to vaginal delivery
2. Known uterine anomaly
3. Multifetal gestation
4. Estimated fetal weight of 4500 gm or greater
5. Ruptured membranes