A 32-year-old primigravida at 34 weeks of gestation presents to the emergency department with sudden onset of vaginal bleeding and severe abdominal pain. On examination, the uterus is tender and rigid. Fetal heart rate is 110 bpm with variable decelerations. Clinical suspicion for abruptio placentae is high. Which investigation is most appropriate to confirm the diagnosis?

## Investigation of Choice for Abruptio Placentae **Key Point:** Transabdominal ultrasound is the investigation of choice for suspected abruptio placentae, though it has limited sensitivity (10–25%) for detecting placental abruption, particularly concealed bleeding. ### Why Ultrasound? 1. **Non-invasive and safe** — no radiation, no risk to mother or fetus 2. **Real-time assessment** — allows evaluation of: - Fetal viability and heart rate - Amniotic fluid volume - Placental location and appearance - Presence of retroplacental clot or hematoma 3. **Guides immediate management** — helps triage for emergency delivery vs. expectant management 4. **First-line imaging** — performed at the bedside in acute settings ### Ultrasound Findings in Abruption | Finding | Sensitivity | Clinical Significance | | --- | --- | --- | | Retroplacental clot | 10–25% | Echogenic or hypoechoic area behind placenta | | Subchorionic hematoma | Variable | May indicate partial separation | | Placental heterogeneity | Low | Non-specific; may suggest bleeding | | Reduced amniotic fluid | Common | Suggests significant abruption | **Clinical Pearl:** The **absence of ultrasound findings does NOT exclude abruptio placentae** — diagnosis is primarily **clinical** (vaginal bleeding + abdominal pain + uterine tenderness + fetal distress). Ultrasound confirms the diagnosis in only ~10–25% of cases; the remainder are diagnosed clinically and by exclusion of placenta previa. **High-Yield:** In acute abruption with fetal distress and maternal hemodynamic instability, do NOT delay delivery waiting for imaging confirmation. Proceed to emergency cesarean section based on clinical grounds. ### Role of Coagulation Studies Coagulation profile and platelet count are **adjunctive investigations**, not diagnostic: - Assess for **disseminated intravascular coagulation (DIC)** — common in severe abruption - Guide transfusion and hemostatic support - NOT used to confirm the diagnosis itself ### Why NOT MRI? - Time-consuming; contraindicated in acute fetal distress - Not standard for obstetric emergencies - Reserved for specific indications (e.g., placental invasion assessment in selected cases) ### Why NOT Amniocentesis? - Amniocentesis for fetal lung maturity is **contraindicated** in abruption (risk of needle trauma, infection, further bleeding) - Fetal maturity assessment is irrelevant if delivery is urgent due to fetal distress or maternal instability