A 28-year-old multigravida (G3P2) at 36 weeks of gestation is admitted with 400 mL of painless vaginal bleeding. She has a history of two previous cesarean deliveries. Vital signs are stable: BP 130/85 mmHg, HR 92 bpm. Transabdominal ultrasound shows a placenta covering the entire internal cervical os with no gap visible. The lower placental edge is <0.5 cm from the os. Fetal biometry is appropriate for gestational age with normal Doppler studies. What is the most likely type of placenta previa, and what is the recommended mode of delivery?

## Classification of Placenta Previa **Key Point:** Placenta previa is classified by the relationship of the lower placental edge to the internal cervical os. The ultrasound finding of placenta covering the entire os with <0.5 cm distance indicates **total (complete) placenta previa**. ### Placenta Previa Classification Table | Type | Definition | Vaginal Delivery | |------|-----------|------------------| | **Marginal** | Lower edge 0–2 cm from internal os | May be attempted if bleeding controlled | | **Partial** | Lower edge covers os but not entirely | Vaginal delivery contraindicated | | **Total/Complete** | Lower edge completely covers internal os | **Cesarean delivery mandatory** | **High-Yield:** Total placenta previa accounts for ~20% of all placenta previa cases and requires **mandatory cesarean delivery** because vaginal delivery is impossible without placental separation and massive hemorrhage. ## Management of Total Placenta Previa at 36 Weeks 1. **Admit for observation** — Monitor for recurrent bleeding. 2. **Administer betamethasone** — Fetal lung maturation (if not already given). 3. **Plan elective cesarean delivery at 37 weeks** — Balances fetal maturity and maternal safety; do not delay beyond 37 weeks due to recurrent hemorrhage risk. 4. **Avoid vaginal delivery** — Impossible and dangerous with total previa. **Clinical Pearl:** The presence of a **previous cesarean scar** increases the risk of placenta accreta spectrum (PAS) in patients with placenta previa. This patient should have a high index of suspicion for PAS and may require MRI if ultrasound is inconclusive. **Mnemonic:** **TOTAL PREVIA = TOTAL CESAREAN** - **T**otal coverage of os - **O**bstetric emergency if labor begins - **T**ransabdominal delivery mandatory - **A**bsolute contraindication to vaginal delivery - **L**ower placental edge completely covers os ## Why Other Options Are Incorrect | Option | Error | |--------|-------| | Marginal previa + vaginal delivery | Misclassification; this is total previa (complete os coverage), not marginal | | Partial previa + TOLAC | Misclassification; partial previa is also contraindicated for vaginal delivery; TOLAC is contraindicated with placenta previa | | Expectant management until 39 weeks + vaginal delivery | Total previa requires cesarean; waiting until 39 weeks increases hemorrhage risk and is unsafe | [cite:Williams Obstetrics 26e Ch 34]