What is the Hnbb method for cervical ripening in a term singleton vertex pregnancy with an unfavorable cervix (Bishop score ≤6) and intact membranes?

Cervical Ripening for Labor Induction: There is No "Hnbb" Method

The term "Hnbb" does not correspond to any recognized cervical ripening method in obstetric practice. You are likely referring to one of the established evidence-based approaches for cervical ripening in a term singleton vertex pregnancy with an unfavorable cervix (Bishop score ≤6).

Standard Evidence-Based Cervical Ripening Methods

Assessment First

• Calculate the Bishop score before initiating any induction regimen to determine whether cervical ripening is needed (score <5 mandates ripening; score ≥5 permits immediate oxytocin). 1, 2
• A Bishop score <6 predicts lower success rates for induction and requires cervical ripening before oxytocin will be effective. 3, 4

Pharmacologic Options

Prostaglandin E2 (Dinoprostone)

• Use dinoprostone vaginal insert (10 mg releasing 0.3 mg/hour) for up to 12 hours maximum for cervical ripening in patients with unfavorable cervix. 1
• Wait at least 30 minutes after removing dinoprostone before starting oxytocin. 1
• Absolute contraindication: active cardiovascular disease due to profound blood pressure effects, coronary vasospasm risk, and arrhythmias. 1
• Relative contraindication in prior cesarean delivery; mechanical methods are preferred in this population. 1
• Requires continuous fetal heart rate and uterine activity monitoring throughout administration. 1

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
• Absolutely contraindicated in women with prior cesarean delivery due to 13% uterine rupture risk. 5, 1

Mechanical Methods

Foley Catheter

• Mechanical cervical ripening (Foley catheter) is the safest option for women with prior cesarean delivery as no uterine ruptures have been reported with this method. 5
• Preferred method for patients with cardiac disease, cyanosis, or any active cardiovascular condition to avoid systemic vascular resistance drops from prostaglandins. 1
• Advantages include low cost, minimal systemic side effects, and low risk of uterine hyperstimulation. 6

Critical Timeline Considerations

• Allow at least 12 hours after completion of cervical ripening, membrane rupture, and oxytocin use before declaring "failed induction" in the latent phase. 1
• Nulliparous women require longer induction times (often 24+ hours total), while multiparous women progress faster with dilation rates ≥1.5 cm/hour. 1
• Premature cesarean delivery for "failed induction" before this 12-hour observation period is a common preventable error. 1

Common Pitfalls to Avoid

• Do not initiate oxytocin when Bishop score is <5 without first performing cervical ripening—oxytocin alone is ineffective in this setting. 1
• Do not use misoprostol in any woman with prior uterine surgery due to catastrophic rupture risk. 5, 1
• Do not use dinoprostone in patients with cardiovascular disease; switch to mechanical methods. 1
• Do not declare induction failure before the mandatory 12-hour observation period. 1

Special Populations

Prior Cesarean Delivery

• Mechanical methods (Foley catheter) are first-line. 5, 1
• Prostaglandin E2 (dinoprostone) may be used with caution (2% rupture risk). 5
• Oxytocin carries 1.1% rupture risk. 5

Cardiac Disease

• Deliver in tertiary centers with multidisciplinary cardiac-obstetric teams. 1
• Use mechanical cervical ripening exclusively; avoid all prostaglandins. 1