For women with a Bishop score ≤6, CR is an important first step in planned induction of labor (IOL). CR is believed to reduce the length of labor induction and increase the probability of a vaginal delivery. Historically, CR has been undertaken on a labor unit. However, with an increased rate of labor induction, the resources of the modern labor unit are incredibly stressed. Compounding the problem is the nursing shortage caused by the COVID-19 pandemic, which has resulted in staff being unavailable as they recover from a respiratory infection or are quarantined after an exposure. The COVID-19 pandemic also has motivated many patients to avoid the hospital as much as possible.
Office-based ambulatory CR is an alternative to inpatient CR and has the potential to reduce the use of labor unit resources. When CR is initiated in the office, the patient either is sent home overnight to return to the labor unit for IOL in the morning or is sent home in the morning to return for IOL in the evening or at night. A secondary benefit of office- and home-based CR is that it may increase patient satisfaction with the process of CR. This editorial summarizes the literature supporting office-based ambulatory CR.
Mechanical methods of CR
Contemporary mechanical methods of CR include the transcervical insertion of a Foley catheter, Cook double-balloon CR catheter, Dilapan-S, or laminaria. There are many publications reporting the feasibility of office-based ambulatory CR with transcervical balloon catheters and very few publications reporting on the use of Dilapan-S or laminaria for ambulatory CR.
Foley catheter
Many studies have investigated the effectiveness of transcervical Foley catheter for ambulatory CR. Policiano and colleagues compared the effectiveness of ambulatory versus inpatient Foley catheter CR.1 A total of 130 women with a Bishop score <6 at ≥41 weeks’ gestation were randomly assigned to outpatient or inpatient CR with a transcervical Foley catheter (Covidian Dover Silicon coated latex Foley catheter 16 Fr/5.3 mm diameter). The Foley catheter bulb was distended with 40 mL of a sterile saline solution. The end of the Foley was taped to the patient’s inner thigh. Manual traction was gently applied to the catheter every 6 hours. If the catheter was extruded, the Bishop score was assessed. For a Bishop score <6, the patient was given additional inpatient misoprostol (25 µg vaginally every 4 hours for up to 5 doses). For a Bishop score ≥6, intravenous oxytocin IOL was initiated. At 24 hours if the Foley catheter was still in situ, it was removed. Women were excluded from the study for the following factors: noncephalic presentation, spontaneous labor, hydramnios, nonreassuring cardiotocography (CTG), multiple pregnancy, ruptured membranes, active vaginal bleeding, Streptococcus group B infection, and HIV infection. Prostaglandin CR was not used if the woman had a previous cesarean delivery. No prophylactic antibiotics were administered. After placement of the Foley catheter, reassuring CTG was documented prior to sending the patient home.
Outpatient, compared with inpatient, CR resulted in a mean reduction of 10 hours in the time from admission to delivery. The time from insertion of the Foley catheter to delivery in the outpatient group was 38.2 hours, and 44.9 hours for the inpatient group (P<.01). The cesarean delivery rates were similar in both groups—28% and 38%, respectively. Three cases of chorioamnionitis occurred in each group. These study results support the feasibility of office-based ambulatory CR with a transcervical Foley.
Ausbeck and colleagues randomly assigned 126 nulliparous women with a Bishop score <5, at a gestational age ranging from 39 weeks and 0 days through 41 weeks and 6 days, to outpatient overnight CR or inpatient CR with a transcervical Foley catheter.2 Breech presentation and multiple gestation pregnancies were excluded from the study. The investigators utilized a 16 French Foley catheter and filled the balloon with 30 mL of sterile water. The Foley was taped to the woman’s inner thigh on slight tension. After placement of the Foley catheter at least 20 minutes of CTG monitoring was performed. The women in the outpatient group were given the contact number for the labor unit and advised that they could take acetaminophen for pain. They were advised that they could stay at home if the Foley catheter was expelled. They were admitted to the labor unit at the time scheduled for their IOL.
The mean time from admission to delivery was reduced by 4.3 hours in the outpatient compared with the inpatient CR group (17.4 vs 21.7 hours; P<.01). In the outpatient CR group, 22% of the women were admitted to labor before the time of the scheduled IOL. The cesarean delivery rates were similar in the outpatient and inpatient CR groups (24% vs 33%, P = .32). In the outpatient and inpatient groups, chorioamnionitis was diagnosed in 22% and 13% (P = .16) of the women. The authors concluded that outpatient CR with a transcervical Foley catheter reduced the time from admission to delivery.
Other research groups also have confirmed the feasibility of outpatient CR with a transcervical Foley catheter.3-5
Placement of the Foley catheter can be performed digitally without direct visualization of the cervix or by direct visualization using a vaginal speculum. After placement of the speculum, the cervix is cleansed with a povidone-iodine solution and a sterile ring forceps is used to grasp the catheter and guide it through the cervical os. In one small study, self-reported pain was similar for both digital and direct visualization methods for placement of the balloon catheter.6 When using Foley catheter CR, filling the standard Foley catheter balloon with 60 mL of fluid, rather than 30 to 40 mL of fluid, is rarely associated with balloon rupture and may result in more effective CR.6,7
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