A 28-year-old primigravida at 39 weeks gestation presents to the labor ward. After 12 hours of active labor, she has failed to progress beyond 6 cm cervical dilation despite adequate uterine contractions. What is the most common indication for cesarean section in this clinical scenario?

Explanation

## Most Common Indication for Cesarean Section in Labor **Key Point:** Failure to progress (arrest of dilation or descent) is the single most common indication for cesarean section in both primigravidas and multiparas, accounting for approximately 30–40% of all cesarean deliveries in India and globally. ### Clinical Context This patient has: - Adequate uterine contractions (meeting criteria for augmentation trial) - Arrest of cervical dilation at 6 cm for ≥2 hours - No fetal or maternal distress mentioned This meets the definition of **arrest of dilation** (previously called cephalopelvic disproportion or CPD, now recognized as a diagnosis of exclusion). ### Pathophysiology & Differential | Indication | Frequency | Mechanism | When Diagnosed | |---|---|---|---| | **Failure to progress** | 30–40% | Inadequate contractions or mechanical obstruction | During active labor | | Cephalopelvic disproportion | ~5–10% | Pelvic inlet/mid-pelvis/outlet obstruction | Diagnosed after trial of labor | | Fetal distress | 10–15% | Hypoxia, cord compression, meconium | Intrapartum on CTG | | Placental abruption | 1–2% | Premature placental separation | Acute, with vaginal bleeding | | Malpresentation | 5–10% | Transverse lie, brow, face | Antenatal or early labor | **High-Yield:** Failure to progress is diagnosed when: 1. Cervical dilation does not advance ≥1 cm/hour in nulliparas (≥1.2 cm/hour in multiparas) for ≥2 hours in active labor, OR 2. Descent of fetal head does not progress for ≥1 hour despite adequate contractions. ### Why This Is Most Common - Affects both primigravidas and multiparas - Often multifactorial (weak contractions, maternal exhaustion, relative CPD) - Requires objective diagnosis and intervention - Cephalopelvic disproportion is now considered part of the spectrum of failure to progress, not a separate entity **Clinical Pearl:** Modern obstetrics no longer diagnoses "true CPD" antenatally; CPD is a retrospective diagnosis made only after a failed trial of labor with adequate contractions. Most cases labeled "CPD" are actually inadequate contractions or maternal fatigue. ### Management Pathway ```mermaid flowchart TD A[Active labor, arrest of dilation]:::outcome --> B{Adequate contractions?}:::decision B -->|No| C[Augmentation with oxytocin]:::action B -->|Yes| D[Reassess after 2 hours]:::action D --> E{Progress?}:::decision E -->|Yes| F[Continue labor]:::action E -->|No| G[Cesarean section for arrest]:::urgent C --> H{Contractions improved?}:::decision H -->|Yes| D H -->|No| G ``` [cite:Williams Obstetrics 26e Ch 21]