What is the recommended induction of labor protocol for a term (≥ 37 weeks) singleton cephalic pregnancy with an unfavorable cervix (Bishop score < 5) and no contraindications to labour?

Protocol for Induction of Labor at Term with Unfavorable Cervix

For a term singleton cephalic pregnancy with an unfavorable cervix (Bishop score <5), begin with cervical ripening using dinoprostone gel (0.5 mg intracervically or 10 mg vaginal insert) followed by oxytocin augmentation after at least 30 minutes, allowing a minimum of 12 hours after completing cervical ripening before considering cesarean delivery for failed induction. 1, 2

Step 1: Assess Cervical Favorability

• Perform Bishop score assessment first to determine if cervical ripening is needed before oxytocin can be effective 1, 2
• Bishop score <5 indicates an unfavorable cervix requiring cervical ripening 3
• Bishop score ≥5 allows proceeding directly to oxytocin and artificial rupture of membranes 3

Step 2: Cervical Ripening for Unfavorable Cervix

Primary Agent: Dinoprostone

Administer dinoprostone as a single 10 mg vaginal insert that releases approximately 0.3 mg/hour, removing it after 12 hours maximum or upon onset of active labor, whichever comes first. 1

• Dinoprostone is FDA-approved for ripening an unfavorable cervix in pregnant women at or near term with a medical or obstetrical need for labor induction 4
• Continuous fetal heart rate monitoring and uterine activity monitoring are mandatory during dinoprostone administration 1
• Wait at least 30 minutes after removing the dinoprostone insert before starting oxytocin 1, 2

Alternative Agent: Oral Misoprostol

• Oral misoprostol 20-25 µg every 2-6 hours results in fewer cesarean sections (RR 0.84) and costs significantly less than dinoprostone 1, 2
• However, misoprostol is absolutely contraindicated in women with prior cesarean delivery due to significantly increased uterine rupture risk (13%) 2, 5

Critical Contraindications to Prostaglandins

• Active cardiovascular disease is an absolute contraindication to dinoprostone due to profound blood pressure effects, theoretical risk of coronary vasospasm, and arrhythmias 3, 1, 2
• In patients with cardiac disease or cyanosis, use mechanical methods (Foley catheter) instead to avoid drops in systemic vascular resistance 3, 5
• Prior cesarean delivery is a relative contraindication for prostaglandins; mechanical methods are preferred 2

Step 3: Oxytocin Augmentation

• After cervical ripening is complete and at least 30 minutes have elapsed since dinoprostone removal, initiate oxytocin infusion per institutional protocol 1, 2
• Oxytocin is indicated for initiation or improvement of uterine contractions in patients with a medical indication for labor induction 6
• Artificial rupture of membranes can be performed as an adjunctive measure when the cervix becomes favorable 2

Step 4: Define Failed Induction

Allow at least 12 hours after completion of cervical ripening, membrane rupture, and oxytocin use before considering cesarean delivery for "failed induction" in the latent phase. 3, 2

• Nulliparous women require longer induction times, often 24+ hours total 2
• Multiparous women progress faster with dilation rates ≥1.5 cm/hour 2
• This patience reduces cesarean delivery rates without compromising maternal or neonatal outcomes 3

Expected Outcomes with This Protocol

• In the ARRIVE trial, 63% of enrolled women had an unfavorable cervix (Bishop score <5) at randomization 3
• Cervical ripening agents were used for women with unfavorable cervix, followed by oxytocin augmentation 3
• This approach resulted in an 18.6% cesarean delivery rate in the induction group versus 22.2% in expectant management (RR 0.84) 3
• Hypertensive disorders were reduced from 14.1% to 9.1% (RR 0.64) with induction at 39 weeks 3, 5

Special Populations Requiring Protocol Modification

Premature Rupture of Membranes (PROM)

• For term PROM with unfavorable cervix, initiate dinoprostone within 6 hours of membrane rupture rather than waiting 6-24 hours 7
• Earlier induction (within 6 hours) significantly reduces cesarean delivery rate (15.8% vs 29.3%, p=0.002) and nonreassuring fetal heart rate tracings (4.8% vs 10.5%, p=0.043) 7

Patients on Anticoagulation

• Switch to unfractionated heparin at least 36 hours before planned induction 2
• Discontinue heparin 4-6 hours before delivery 2
• Women on prophylactic low-molecular-weight heparin should be allowed spontaneous labor when possible rather than scheduled induction 5

High-Risk Cardiac Patients

• Deliver in tertiary centers with specialist multidisciplinary team care 3, 2
• Use mechanical methods (Foley catheter) for cervical ripening instead of prostaglandins 3, 5
• Avoid dinoprostone entirely due to profound blood pressure effects 3, 1, 2

Common Pitfalls to Avoid

• Do not proceed directly to oxytocin without cervical ripening when Bishop score <5 – oxytocin cannot be effective without a favorable cervix 1, 2
• Do not declare failed induction before allowing at least 12 hours after completing cervical ripening, membrane rupture, and oxytocin use 3, 2
• Do not use misoprostol in women with prior cesarean delivery due to 13% uterine rupture risk 2, 5
• Do not use dinoprostone in patients with active cardiovascular disease due to profound hemodynamic effects 3, 1, 2
• Do not start oxytocin immediately after dinoprostone removal – wait at least 30 minutes 1, 2