A 28-year-old primigravida at 39 weeks gestation presents to the labor ward. After 12 hours of active labor, she has minimal cervical progress. Vaginal examination reveals a well-flexed vertex presentation at −2 station with a gynecoid pelvis. 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 in labor (FTP) is the single most common indication for cesarean section in developed countries, accounting for 20–30% of all cesarean deliveries. ### Definition and Classification Failure to progress encompasses two distinct patterns: 1. **Arrest of dilation** — cervical dilation does not change for ≥2 hours (nullipara) or ≥1 hour (multipara) during active labor 2. **Arrest of descent** — descent of the fetal head does not occur for ≥1 hour (nullipara) or ≥30 minutes (multipara) in the second stage ### Why FTP is the Most Common Indication **High-Yield:** In the scenario presented, the patient has been in active labor for 12 hours with minimal cervical progress — this meets the diagnostic criteria for arrest of dilation, which falls under the broader diagnosis of failure to progress in labor. This is the most frequent single indication for primary cesarean delivery in nulliparous women. ### Epidemiology and Risk Factors | Factor | Association with FTP | |--------|----------------------| | Maternal age > 35 years | Increased risk | | Obesity (BMI > 30) | Increased risk | | Induction of labor | Increased risk | | Epidural anesthesia | May prolong labor (not direct cause) | | Inadequate uterine contractions | Treatable cause | **Clinical Pearl:** Before diagnosing arrest of dilation, it is essential to confirm that the patient is in active labor (cervical dilation ≥6 cm with regular contractions). Inadequate contractions should be managed with oxytocin augmentation before resorting to cesarean delivery. ### Distinction from Related Diagnoses **Warning:** Do not confuse: - **Arrest of dilation** (FTP in first stage) with **cephalopelvic disproportion** (CPD) — CPD is a diagnosis of exclusion made only after ruling out inadequate contractions - **Prolonged latent phase** (>20 hours in nullipara) with arrest of dilation — these are separate diagnoses with different management approaches **Mnemonic: FTP Indications — "DADS"** - **D**ilation arrest (first stage) - **A**rrest of descent (second stage) - **D**ecelerations (fetal heart rate) - **S**talled progress (overall) [cite:Williams Obstetrics 26e Ch 21]