What is the management for a woman of childbearing age experiencing an arrest of dilation during labor?

Management of Arrest of Dilation During Labor

For a woman experiencing arrest of dilation in labor, initiate oxytocin augmentation combined with amniotomy after confirming cervical dilation ≥6 cm and ruling out cephalopelvic disproportion, continuing for at least 4 hours of adequate contractions before considering cesarean delivery. 1, 2, 3

Confirm the Diagnosis First

Before intervening, verify that true active phase arrest exists:

• Cervical dilation must be ≥6 cm to diagnose active phase arrest—anything less represents latent phase, not arrest 2
• No cervical change for ≥4 hours despite adequate contractions (≥200 Montevideo units), OR no change for ≥6 hours with inadequate contractions despite oxytocin 2
• Perform vaginal examinations every 2 hours to accurately track dilation progress 2

Critical Pre-Intervention Assessment: Rule Out Cephalopelvic Disproportion

Before starting oxytocin, you must evaluate for CPD, which occurs in 25-30% of active phase arrest cases 1, 2, 3:

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

If CPD is confirmed or suspected, proceed directly to cesarean delivery—oxytocin is contraindicated 1, 3

Evidence-Based Management Algorithm When CPD is Excluded

Step 1: Amniotomy Combined with Oxytocin Augmentation

• Amniotomy alone rarely produces further dilation; the American College of Obstetricians and Gynecologists recommends combining it with oxytocin 1
• This combination achieves a 92% vaginal delivery success rate when CPD is not present 3

Step 2: Oxytocin Administration Protocol

Follow FDA-approved dosing 4:

• Start at 1-2 mU/min and increase by 1-2 mU/min increments every 15 minutes 1
• Target 7 contractions per 15 minutes or ≥200 Montevideo units 1, 2
• Maximum dose: 36 mU/min 1
• Use an infusion pump for accurate control 4

Step 3: Monitoring During Augmentation

• Perform serial cervical examinations every 2 hours after amniotomy 1
• Continuously monitor fetal heart rate patterns 1, 3
• Monitor contraction frequency, duration, and intensity 1
• Watch for increasingly marked molding, deflexion, or asynclitism without descent as signs of emerging CPD 1
• Discontinue oxytocin immediately if uterine hyperstimulation or fetal distress occurs 3, 4

Step 4: Decision Point After 4 Hours

If no progress occurs after 4 hours of adequate contractions (≥200 Montevideo units) 1, 3, 5:

• Reassess for CPD 1, 3
• If CPD is confirmed or suspected, proceed to cesarean delivery 1
• If CPD is excluded, oxytocin titration can be continued 1

The evidence supporting 4 hours of augmentation is robust, with a 1999 study showing 92% vaginal delivery rates overall (88% for parous women, 56% for nulliparas with no progress after 4 hours) 5

Important Clinical Caveats

Recent evidence suggests that allowing 4 hours of arrest may be too long after 6 cm dilation, with 2 hours being safer 1. This reflects evolving understanding that the traditional 4-hour window may increase risks of postpartum hemorrhage and intraamniotic infection in late labor 6.

Common pitfall: Do not diagnose arrest before 6 cm dilation—contractions increase inconsistently in latent phase and provide limited diagnostic value for determining active phase 2. Misdiagnosing latent phase as active phase arrest leads to unnecessary interventions.

Safety consideration: Oxytocin must be discontinued immediately if signs of fetal distress or uterine hyperactivity occur, with oxygen administered to the mother and immediate physician evaluation 3, 4