A 32-year-old primigravida at 28 weeks gestation presents with sudden onset vaginal bleeding and abdominal pain. Ultrasound confirms placental abruption. Which of the following is the most common risk factor associated with abruptio placentae in this patient?

Explanation

## Most Common Risk Factor in Abruptio Placentae **Key Point:** Maternal hypertension (chronic hypertension or preeclampsia/eclampsia) is the single most common and well-established risk factor for placental abruption, accounting for approximately 40–50% of cases. ### Pathophysiology Hypertension causes: 1. Endothelial damage and placental ischemia 2. Increased placental vascular fragility 3. Separation of placental villi from decidua 4. Retroplacental hemorrhage ### Risk Factors for Abruptio Placentae — Comparative Table | Risk Factor | Frequency | Mechanism | | --- | --- | --- | | **Maternal hypertension** | **Most common (40–50%)** | **Endothelial damage, placental ischemia** | | Trauma / blunt abdominal injury | Common | Direct placental separation | | Maternal smoking | Common | Placental insufficiency, vascular fragility | | Cocaine use | Common | Acute hypertension, vasoconstriction | | Placental abruption in prior pregnancy | Moderate | Recurrence risk ~25% | | Preeclampsia/eclampsia | Very common | Severe endothelial dysfunction | | Uterine anomalies | Uncommon | Abnormal placentation | | Polyhydramnios | Rare | Uterine overdistension | | Placenta previa | Not associated | Different pathology | **High-Yield:** Hypertension is the leading preventable risk factor; tight BP control in pregnancy reduces abruption risk. **Clinical Pearl:** In a patient presenting with APH, always check BP and urine protein — preeclampsia may be the underlying cause. ### Why Hypertension Stands Out - Present in ~40–50% of abruption cases - Both chronic hypertension and pregnancy-induced hypertension (preeclampsia) increase risk - Dose-dependent relationship: higher BP = higher risk - Reversible with antihypertensive therapy [cite:Williams Obstetrics 26e Ch 34]