Failed Balloon Catheter Induction

Failed balloon catheter induction is failure of a Foley or double balloon catheter to ripen the cervix, shown by the balloon staying in place after 24 hours without cervical change, or by a cervix still less than 3 cm dilated with a Bishop score below 6 after expulsion. It results from a very unripe cervix, anxiety, malposition, a short catheter time or low balloon volume. It matters because balloon catheters are the only mechanical option in a scarred uterus, and failure can end in caesarean section.

• Risk factors: first pregnancy, Bishop score below 4, body mass index above 30 kg/m2, post term pregnancy, previous cervical surgery.
• A Foley catheter (16 to 18 French) with a 30 mL balloon is used.
• Oxytocin or misoprostol used together with the catheter shorten induction.

Women have little pain, no or irregular contractions and a catheter that remains in place. After removal, the cervix is long and closed or minimally dilated.

• Cervix 0 to 2 cm dilated with a firm consistency.
• Mild spotting at insertion is common.
• Differential diagnosis: catheter placed below the internal os, inadequate balloon volume, wrong gestation, cervical scarring, latent phase, inappropriate indication.
• Complications: prolonged induction, maternal discomfort, intrauterine infection, membrane rupture, cord prolapse (rare), caesarean section, bleeding from low lying placenta.

The diagnosis is made by assessing the cervix after 12 to 24 hours of the catheter, or on its expulsion.

• Bishop score before insertion and after removal; record whether the balloon was expelled spontaneously and at what dilatation.
• Check catheter position and balloon volume (30 mL sterile water); exclude placenta previa before insertion.
• Cardiotocography; maternal temperature and pulse; ultrasound for presentation and liquor.
• Review the indication and urgency.

The principle is to add a pharmacological method or amniotomy, and to deliver by caesarean section when the cervix remains unripe and birth is urgent.

• Supportive: explain the options; rest and fluids; leave the catheter in for up to 24 hours; remove it earlier if contractions start, bleeding occurs, membranes rupture or the tracing is abnormal; continuous cardiotocography in high risk women.
• Pharmacological: 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) with the balloon in place or after removal; misoprostol 25 micrograms vaginal 6-hourly (maximum 4 doses) in an unscarred uterus; mifepristone 200 mg oral once followed 24 hours later by misoprostol where available; ampicillin 2 g IV 6-hourly plus gentamicin 5 mg/kg IV once daily for chorioamnionitis; benzylpenicillin 5 million units IV then 2.5 million units 4-hourly for rupture of 18 hours or more; cefazolin 2 g IV before caesarean section.
• Procedures: reinsertion of a Foley catheter with a 30 mL balloon, or a double balloon catheter, after 12 hours of rest; amniotomy when the cervix is 2 to 3 cm dilated and the head is engaged; caesarean section for fetal compromise, infection, a strong indication to deliver, or failure after a second course.
• Special groups: a uterine scar uses a Foley catheter alone or oxytocin with senior review, with misoprostol and dinoprostone avoided; low lying placenta contraindicates balloon catheter insertion until previa is excluded.
• Red flags: fever above 38 degrees Celsius, bleeding, tachysystole, abnormal fetal heart rate, scar pain, cord prolapse.
• Follow-up: repeat Bishop score at 12 to 24 hours; maternal temperature 4-hourly; newborn sepsis surveillance if infection occurred; review at 6 weeks.