What is the next step in managing a primigravida at 38 weeks gestation with arrested labor and no change in cervical dilation after 4 hours?

Management of Arrested Labor in a Primigravida at 38 Weeks Gestation

Intravenous oxytocin administration is the most appropriate next step in management for this patient with arrested labor despite adequate contraction strength. 1

Assessment of the Current Situation

• The patient is a 23-year-old primigravida at 38 weeks with spontaneous rupture of membranes and painful contractions
• Cervical examination shows 8 cm dilation, 90% effacement, with the head at 0 station
• Contraction strength is 200 Montevideo units every 10 minutes (adequate strength)
• After 4 hours, the cervix remains unchanged despite adequate contractions
• Fetal heart rate tracing is normal

Management Algorithm

Step 1: Confirm Diagnosis of Active Phase Arrest

• Active phase arrest is defined as no cervical change despite adequate uterine contractions 1
• The patient meets criteria with 4 hours of no cervical change despite 200 Montevideo units of contraction strength 1

Step 2: Evaluate for Potential Causes

• Assess for cephalopelvic disproportion (CPD), which occurs in 25-30% of active phase arrest cases 1, 2
• Consider other factors: fetal malposition, macrosomia, or insufficient uterine contractility 1
• In this case, estimated fetal weight is 3600g (8lb), which is not macrosomic

Step 3: Select Appropriate Intervention

• Oxytocin augmentation is the first-line treatment for active phase arrest when CPD is not evident 1, 3
• Research shows that extending oxytocin augmentation for at least 4 hours in active-phase arrest is safe and effective 4, 5
• Oxytocin should be titrated carefully to avoid uterine hyperstimulation 1, 3

Why Oxytocin is the Correct Choice

• The patient has adequate contractions (200 Montevideo units) but may benefit from enhanced uterine activity 1
• FDA guidelines support oxytocin use for stimulation of labor when progress is inadequate 3
• Studies show that 92% of women with active-phase arrest delivered vaginally after oxytocin augmentation 4
• Even with no progress after 2 hours of oxytocin, 74% of nulliparas still achieved vaginal delivery 4

Why Other Options Are Not Appropriate

• Amnioinfusion (Option A): Not indicated as there is no evidence of cord compression or thick meconium 6
• Cervical examination in 2 hours (Option B): Delaying intervention is not appropriate when active phase arrest is already established 1
• Cesarean delivery (Option C): Premature without first attempting oxytocin augmentation 1, 2
• Operative vaginal delivery (Option E): Contraindicated at 8cm dilation (not fully dilated) 1

Important Considerations

• Monitor fetal heart rate closely during oxytocin administration to detect any signs of distress 3
• If no progress occurs after 4 hours of adequate oxytocin augmentation, reassess for CPD 1, 2
• If evidence of CPD emerges (increasing molding, deflexion, or asynclitism without descent), consider cesarean delivery 1, 2
• The presence of normal fetal heart rate tracing supports continued labor management rather than immediate cesarean 1

Oxytocin Administration Protocol

• Start at a low dose (1-2 mU/min) and increase gradually in increments of 1-2 mU/min 3
• Titrate to achieve effective contractions while avoiding uterine hyperstimulation 3
• Discontinue immediately if signs of fetal distress or uterine hyperactivity occur 3
• Continue for at least 4 hours before considering cesarean for arrest if fetal status remains reassuring 4, 5