Failed Cervical Ripening

Failed cervical ripening is failure of the cervix to become favourable (Bishop score below 6, or less than 3 cm dilated) after a full course of a ripening method, which is misoprostol for 4 doses or a Foley catheter for 12 to 24 hours. It results from poor sensitivity of the cervix, scarring from previous surgery, anxiety, wrong dates or an inappropriate indication. It matters because induction cannot proceed to labour with an unripe cervix, and repeated attempts waste time and expose mother and baby to risk.

• Risk factors: first pregnancy, body mass index above 30 kg/m2, previous cervical surgery, post term pregnancy with a long cervix, maternal age above 35 years.
• Combined methods work better than one method alone.
• Simple rest between attempts is helpful.

Women have had ripening with little or no change in the cervix, with few contractions or irregular painful contractions. The cervix remains long, firm and closed or only slightly open.

• Bishop score below 6 after treatment.
• Contractions may be absent.
• Differential diagnosis: wrong gestation, cervical scarring or stenosis, drug not absorbed or expelled, inappropriate indication, latent phase of labour.
• Complications: prolonged induction, exhaustion, infection if membranes are ruptured, tachysystole, fetal distress, caesarean section.

The diagnosis is made by repeating the Bishop score after the course of treatment.

• Bishop score: dilatation (0 to 3), effacement (0 to 3), station (0 to 3), consistency (0 to 2), position (0 to 2); a score of 6 or more is favourable.
• Check that the agent was correctly placed or still in place, and the dose and timing.
• Cardiotocography; ultrasound for gestation, fetal weight, presentation and liquor.
• Review of the indication and a decision on how urgent birth is.

The principle is to review the need to deliver, then change or combine methods, rest, or deliver by caesarean section if birth is urgent.

• Supportive: rest and feeding for 12 to 24 hours if mother and fetus are well; reassurance; outpatient wait when the indication allows; membrane sweeping at examination; continuous cardiotocography during ripening in high risk women.
• Pharmacological: misoprostol 25 micrograms vaginal 6-hourly (maximum 4 doses), or misoprostol 25 micrograms oral 2-hourly for up to 6 doses, in an unscarred uterus; Foley catheter 30 mL balloon with oxytocin 10 IU in 1 litre Ringer's lactate (10 mU/mL) started at 12 mL per hour (2 mU/minute) and doubled every 30 minutes to a maximum of 192 mL per hour (32 mU/minute); mifepristone 200 mg oral once, followed by misoprostol 25 micrograms vaginal 6-hourly (maximum 4 doses) 24 hours later, where available; dinoprostone 10 mg vaginal insert for up to 24 hours where available; cefazolin 2 g IV before caesarean section.
• Procedures: Foley catheter ripening for 12 to 24 hours; combined Foley catheter and misoprostol; amniotomy once the cervix is 2 to 3 cm dilated and the head is engaged; caesarean section for fetal compromise, a strong indication to deliver, or no response to two courses.
• Special groups: a uterine scar avoids misoprostol, dinoprostone and mifepristone and uses a Foley catheter alone or elective caesarean section; women with high blood pressure or growth restriction have shorter waits before caesarean section.
• Red flags: tachysystole, fetal heart rate abnormality, bleeding, scar pain, fever above 38 degrees Celsius.
• Follow-up: repeat Bishop score after each course; maternal temperature 4-hourly if membranes ruptured; review at 6 weeks; counselling about the next induction.