A 32-year-old primigravida at 34 weeks gestation presents to the emergency department with sudden onset vaginal bleeding and severe abdominal pain. On examination, she is hemodynamically unstable (BP 90/60 mmHg, HR 110/min), with a rigid, tender uterus and vaginal bleeding. Fetal heart rate is 80 bpm with minimal variability. What is the investigation of choice to confirm the diagnosis of abruptio placentae?

Explanation

## Diagnosis of Abruptio Placentae **Key Point:** In suspected abruptio placentae, clinical diagnosis is paramount and should NOT be delayed by investigations. However, when imaging is needed, **transabdominal ultrasonography (USG) is the investigation of choice** — it is rapid, non-invasive, and available at the bedside. ### Role of Ultrasonography **High-Yield:** USG can identify: - Retroplacental hematoma (echogenic collection behind the placenta) - Subchorionic hemorrhage - Placental abruption with clot formation - Fetal viability and heart rate - Amniotic fluid volume - Fetal biometry **Clinical Pearl:** USG sensitivity for abruption is only 50–60%, meaning a **negative USG does NOT exclude abruption**. Diagnosis remains primarily **clinical** — based on vaginal bleeding, abdominal pain, uterine tenderness, and fetal distress. ### Why USG Is Preferred | Feature | Transabdominal USG | MRI | Amniocentesis | Coagulation Studies | |---------|-------------------|-----|----------------|---------------------| | **Speed** | Immediate (bedside) | 30–60 min | Not indicated | Minutes | | **Safety** | Safe in pregnancy | Safe but slow | Contraindicated (risk of further bleeding) | Supportive only | | **Diagnostic value** | Visualizes clot, fetal status | High sensitivity but not first-line | None (diagnostic) | None (diagnostic) | | **First-line?** | **Yes** | No (reserved for atypical cases) | No | No | **Warning:** In a hemodynamically unstable patient with clinical signs of abruption, **do NOT delay management for imaging**. Proceed to delivery (emergency cesarean section) based on clinical diagnosis alone. ### Role of Coagulation Studies Coagulation profile and fibrinogen are **supportive investigations**, not diagnostic: - Used to assess **disseminated intravascular coagulation (DIC)** — a complication of severe abruption - Guide transfusion and management - NOT used to confirm abruption itself [cite:Williams Obstetrics 26e Ch 34] ---