A 39‑week multigravida with a fully effaced cervix is now 5 cm dilated after 4 hours of strong regular contractions; what is the most appropriate next step in management?

Management of Protracted Active Phase Labor

The most appropriate next step is amniotomy combined with oxytocin augmentation (Option B/C combined), after first excluding cephalopelvic disproportion. 1

Diagnostic Confirmation

This multigravida has protracted active phase labor, defined as cervical dilation slower than 1.5 cm/hour in multiparous patients or below the minimum acceptable rate of 0.6 cm/hour. 1 Her progression of 1 cm over 4 hours (0.25 cm/hour) clearly meets diagnostic criteria. 1

• At 4-5 cm dilation with strong regular contractions, she is definitively in the active phase of labor, not the latent phase. 1
• The fully effaced cervix confirms active labor status. 1

Critical Pre-Intervention Assessment

Before initiating augmentation, you must exclude cephalopelvic disproportion (CPD), which occurs in 25-30% of protracted active phase cases. 1

Assess for:

• Fetal malposition (occiput posterior/transverse) 1
• Excessive molding, deflexion, or asynclitism without descent 1
• Fetal macrosomia, maternal diabetes, or obesity 1
• Suprapubic palpation to differentiate true descent from molding 1

If CPD is confirmed or suspected, proceed directly to cesarean delivery (Option A). 1 Oxytocin is contraindicated when CPD cannot be excluded because obstructed labor increases uterine rupture risk. 1

Evidence-Based Management Algorithm

When CPD is ruled out, the recommended management is combined amniotomy with oxytocin augmentation. 1

• Amniotomy alone rarely produces further dilation and is insufficient as monotherapy. 1
• The combination approach is the evidence-based standard per the American College of Obstetricians and Gynecologists. 1

Oxytocin Protocol

• Start at 1-2 mU/min and increase by 1-2 mU/min increments every 15 minutes 1
• Target 7 contractions per 15 minutes 1
• Maximum dose 36 mU/min 1
• Immediately discontinue if uterine hyperstimulation or fetal distress develops 1

Monitoring and Decision Points

• Perform serial cervical examinations every 2 hours after amniotomy 1
• Continuously monitor fetal heart rate patterns, contraction frequency, duration, and intensity 1

If no cervical progress occurs after 4 hours of adequate contractions:

• Reassess for CPD 1
• If CPD confirmed or suspected → cesarean delivery 1
• If CPD excluded → continue oxytocin titration 1

At 4-5 cm dilation, the traditional 4-hour observation window remains appropriate before declaring arrest. 1 Recent evidence suggests 2-hour windows may be safer after 6 cm, but not at this earlier dilation. 1

Why Other Options Are Incorrect

• Option A (Cesarean section): Premature without evidence of CPD or fetal compromise; cesarean is reserved for confirmed CPD or failed augmentation. 1
• Option C (Amniotomy alone): Insufficient as monotherapy and should be paired with oxytocin. 1
• Option D (Reassess after 2 hours): Inappropriate because she already meets diagnostic criteria for protracted active phase labor requiring active management, not further observation. 1

Common Pitfalls

• Do not delay intervention once protracted active phase is diagnosed—expectant management is only appropriate for latent phase labor. 1
• Do not start oxytocin without first excluding CPD—this creates dangerous obstructed labor. 1
• Watch for increasingly marked molding, deflexion, or asynclitism without descent during augmentation as signs of emerging CPD. 1