A 28-year-old primigravida at 39 weeks of gestation presents to the labour ward with regular uterine contractions. On examination, cervical dilation is 3 cm, and the fetal head is at −2 station. Fetal heart rate is 140 bpm with normal variability. After 6 hours of augmentation with oxytocin, cervical dilation remains 3 cm with no descent of the fetal head. Pelvic assessment suggests adequate pelvic dimensions. What is the most appropriate next step in management?

Explanation

## Diagnosis: Arrest Disorder of Labour (Prolonged Latent Phase / Arrest of Dilation) ### Clinical Context This primigravida has failed to progress despite adequate uterine contractions and oxytocin augmentation for 6 hours. The cervix remains at 3 cm with no descent—meeting criteria for **arrest of dilation**. ### Diagnostic Criteria for Arrest of Dilation | Feature | Nullipara | Multipara | | --- | --- | --- | | **Duration of no cervical change** | ≥4 hours with adequate contractions | ≥2–3 hours with adequate contractions | | **Adequate contractions** | ≥200 Montevideo units in 10 min | ≥200 Montevideo units in 10 min | | **Station at arrest** | Usually −2 to 0 | Variable | **Key Point:** In this case, 6 hours of no cervical change in a nullipara with augmentation constitutes arrest of dilation and is an indication for cesarean delivery. ### Management Algorithm ```mermaid flowchart TD A[Labour with inadequate progress]:::outcome --> B{Adequate contractions?}:::decision B -->|No| C[Augment with oxytocin]:::action B -->|Yes| D{Cervical change after 4-6 hrs?}:::decision C --> E{Response to oxytocin?}:::decision E -->|Yes, progress| F[Continue labour management]:::action E -->|No progress after 4-6 hrs| G[Arrest of dilation]:::outcome D -->|Yes| F D -->|No| G G --> H{Maternal/fetal compromise?}:::decision H -->|Yes| I[Cesarean section]:::action H -->|No, stable| J{Cephalopelvic disproportion?}:::decision J -->|Likely| I J -->|Unlikely| K[Consider trial of labour vs CS]:::decision ``` ### Why Cesarean Section? **High-Yield:** According to ACOG (2019) and WHO guidelines, arrest of dilation in active labour despite adequate contractions and augmentation for ≥4 hours in a nullipara is an absolute indication for cesarean delivery. **Clinical Pearl:** Arrest disorders carry increased risk of: - Maternal exhaustion and infection - Fetal hypoxia and acidosis - Prolonged labour complications - Uterine rupture (if further augmentation attempted) **Key Point:** The pelvic assessment is adequate, but the **failure to progress despite adequate contractions** is the key indication—this suggests either: 1. Inadequate uterine contractility (despite oxytocin) 2. Cephalopelvic disproportion (CPD) undetected on clinical pelvimetry 3. Malposition of the fetal head ### Why Not the Other Options? - **Continuing oxytocin for 4 more hours:** This is unsafe. The patient has already had 6 hours of adequate augmentation with no progress. Further delay increases maternal and fetal morbidity. - **Artificial rupture of membranes (ARM):** While ARM can be used in early labour to augment contractions, it does not address the underlying arrest and may increase infection risk if labour is prolonged further. - **Epidural and expectant management:** Analgesia is appropriate, but expectant management without progress is not indicated in arrest of dilation. Delaying cesarean increases complications. [cite:ACOG Practice Bulletin 49, WHO Labour Care Guidelines]