A 39‑week multigravida in active labor is 4 cm dilated with strong regular contractions; after 4 hours she is only 5 cm dilated. What is the appropriate management?

Management of Protracted Active Phase Labor

This multigravida with protracted active phase labor (0.25 cm/hour over 4 hours) should receive combined amniotomy with oxytocin augmentation after excluding cephalopelvic disproportion (CPD)—the answer is B (Oxytocin) combined with C (amniotomy).

Diagnostic Confirmation

This patient clearly has protracted active phase labor, defined as cervical dilation less than 1.5 cm/hour in multiparas 1. Her rate of 1 cm over 4 hours (0.25 cm/hour) is well below the minimum acceptable threshold of 0.6 cm/hour 1, 2.

• At 4 cm with strong regular contractions, she is definitively in active phase labor 1
• The diagnosis of protracted active phase cannot be made until active phase is confirmed, which it is in this case 1

Critical Pre-Intervention Assessment: Rule Out CPD

Before any intervention, you must evaluate for cephalopelvic disproportion, which occurs in 25-30% of protracted active phase cases 1, 2:

• Assess fetal position for malposition (occiput posterior/transverse) 2
• Evaluate for excessive molding, deflexion, or asynclitism without descent 2
• Consider fetal macrosomia, maternal diabetes, obesity, and pelvic adequacy 1, 2
• Perform suprapubic palpation to differentiate true descent from molding 2

If CPD is confirmed or suspected, proceed directly to cesarean delivery—oxytocin is contraindicated 2, 3.

Evidence-Based Management Algorithm

If CPD is excluded, the recommended management is combined amniotomy with oxytocin augmentation 2:

• Amniotomy alone is insufficient—it rarely produces further dilation and must be paired with oxytocin 2
• Start oxytocin at 1-2 mU/min, increase by 1-2 mU/min every 15 minutes 4
• Target adequate contractions (≥200 Montevideo units or 7 contractions per 15 minutes) 2, 5
• Maximum dose 36 mU/min with continuous fetal heart rate monitoring 2, 4

Monitoring and Decision Points

• Perform serial cervical examinations every 2 hours after initiating augmentation 2
• If no cervical progress occurs after 4 hours of adequate contractions at 4-5 cm dilation, reassess for CPD 2, 5
• Recent evidence suggests that at higher dilations (after 6 cm), a 2-hour window may be safer than 4 hours, but at 4-5 cm the traditional 4-hour window remains appropriate 2
• If CPD is confirmed during augmentation, proceed to cesarean delivery 2
• If CPD is excluded, continue oxytocin titration 2

Why Other Options Are Incorrect

• Option A (Cesarean section): Premature—not indicated without evidence of CPD or failure of augmentation after adequate trial 2, 5
• Option C (Amniotomy alone): Insufficient—rarely results in further dilation without oxytocin 2
• Option D (Reassess after 2 hours): Inappropriate—she already meets diagnostic criteria for protracted active phase requiring intervention, not further observation 1, 2

Safety Monitoring

• Immediately discontinue oxytocin if uterine hyperstimulation or fetal distress develops 2, 4
• Watch for increasingly marked molding, deflexion, or asynclitism without descent as signs of emerging CPD during augmentation 2
• A good response (effective contractions with progressive dilation) predicts favorable vaginal delivery outcome 2, 5
• Studies show 92% vaginal delivery rate overall with this protocol, with 74% success in nulliparas and higher rates in multiparas 5