A 28-year-old multiparous woman at 34 weeks gestation with chronic hypertension presents with sudden-onset severe abdominal pain, vaginal bleeding, and fetal bradycardia. Ultrasound shows a large retroplacental clot. Which laboratory finding best distinguishes severe abruptio placentae from severe placenta previa in terms of maternal coagulopathy?

Explanation

## Coagulopathy in Severe Abruptio Placentae vs. Placenta Previa ### Key Discriminating Feature **Key Point:** Severe abruptio placentae causes **disseminated intravascular coagulation (DIC)** with consumption of clotting factors and platelets, resulting in prolonged PT/aPTT and hypofibrinogenemia. Placenta previa does NOT cause DIC unless there is massive hemorrhage requiring massive transfusion. ### Comparative Table: Coagulation Profile | Coagulation Parameter | Severe Abruptio Placentae | Severe Placenta Previa | |----------------------|---------------------------|------------------------| | **PT** | Prolonged | Normal | | **aPTT** | Prolonged | Normal | | **Fibrinogen** | **Markedly decreased (<100 mg/dL)** | Normal (>200 mg/dL) | | **Platelet count** | Decreased (thrombocytopenia) | Normal or mildly decreased | | **D-dimer** | Markedly elevated | Mildly elevated | | **Mechanism** | DIC (tissue factor release) | Hemorrhage alone | | **Clinical consequence** | Bleeding from multiple sites; surgical bleeding | Bleeding controlled by transfusion | ### Pathophysiology of DIC in Abruptio Placentae 1. **Tissue factor release:** Placental separation exposes thromboplastin in the intervillous space 2. **Thrombin generation:** Massive activation of coagulation cascade 3. **Fibrin deposition:** Consumption of fibrinogen, prothrombin, and factors V and VIII 4. **Platelet consumption:** Microthrombi formation → thrombocytopenia 5. **Secondary fibrinolysis:** Elevated D-dimer and FDP; further fibrinogen consumption ### Clinical Pearl **Clinical Pearl:** The presence of **hypofibrinogenemia (<100 mg/dL)** in a bleeding pregnant woman is virtually pathognomonic for abruptio placentae with DIC. Placenta previa bleeding, even if massive, does NOT consume fibrinogen unless the patient has received massive transfusions (which triggers dilutional coagulopathy, not true DIC). ### High-Yield Facts **High-Yield:** - **Fibrinogen is the most sensitive marker** of DIC in abruptio placentae; it drops before PT/aPTT becomes prolonged - Serial fibrinogen measurement (every 1–2 hours) guides transfusion strategy - A fibrinogen <100 mg/dL warrants fresh frozen plasma (FFP) or cryoprecipitate - Placenta previa does NOT cause DIC unless there is massive concealed hemorrhage (rare) or the patient is in hemorrhagic shock ### Mnemonic **Mnemonic:** **DIC in Abruptio = Disseminated Intravascular Coagulation; tissue factor release → Decreased fibrinogen, Increased PT/aPTT, Consumption of platelets** ### Why This Matters **Tip:** In NEET PG exams, a question about "coagulopathy in APH" is almost always testing whether you know that **abruptio placentae causes DIC** (with low fibrinogen) while **placenta previa does not** (unless massive transfusion). This is a high-yield discriminator.