A 32-year-old woman, gravida 3 para 2, presents at 38 weeks gestation for antenatal evaluation. Obstetric ultrasound reveals complete placenta previa with the placental edge 1.5 cm from the internal cervical os. She is hemodynamically stable with no vaginal bleeding. Her previous two deliveries were both vaginal. What is the most appropriate plan for delivery?

Explanation

## Management of Complete Placenta Previa **Key Point:** Complete placenta previa (placental edge ≤2 cm from internal cervical os) is an absolute contraindication to vaginal delivery and requires planned cesarean section at 39 weeks gestation in stable, asymptomatic patients. ### Classification of Placenta Previa | Type | Definition | Vaginal Delivery Possible? | |------|-----------|---------------------------| | **Complete previa** | Placental edge covers internal os completely | **NO** — absolute contraindication | | **Partial previa** | Placental edge partially covers os | NO — relative contraindication | | **Marginal previa** | Placental edge ≤2 cm from os | NO — relative contraindication | | **Low-lying placenta** | Placental edge >2 cm from os | YES — may attempt vaginal delivery | **High-Yield:** This patient has **complete previa** (edge 1.5 cm from os = within 2 cm margin, and described as "complete") → **absolute contraindication to vaginal delivery**. ### Rationale for Planned Cesarean at 39 Weeks 1. **ACOG Guideline:** Planned cesarean delivery is standard for complete and partial placenta previa [cite:ACOG Practice Bulletin 203] 2. **Timing:** 39 weeks balances fetal maturity with risk of antepartum hemorrhage 3. **Asymptomatic, stable:** No indication for earlier delivery (37 weeks) unless recurrent bleeding or other complications 4. **Previous vaginal deliveries:** Do NOT change management; placenta previa is anatomic, not affected by parity ### Why NOT Vaginal Delivery - Placental tissue will obstruct the birth canal - Risk of massive hemorrhage (placenta is highly vascularized) - Fetal death or severe morbidity from placental separation during labor - Even "trial of labor" is contraindicated **Clinical Pearl:** Placenta previa is one of the few absolute contraindications to trial of labor. Unlike arrest disorders or previous cesarean, there is no role for vaginal delivery attempt. ### Management Flowchart ```mermaid flowchart TD A[Placenta previa diagnosed]:::outcome --> B{Type of previa?}:::decision B -->|Complete or partial| C[Cesarean delivery]:::action B -->|Marginal or low-lying| D{Bleeding episodes?}:::decision D -->|Yes, recurrent| E[Cesarean delivery]:::action D -->|No| F[Trial of vaginal delivery possible]:::action C --> G[Plan delivery at 39 weeks if stable]:::action E --> G ``` **Mnemonic:** **PREVIA** = **P**lanned **C**esarean, **R**outine at 39 weeks, **E**xpect **V**aginal delivery only if **I**ncomplete or **A**way from os.