The most impoant cause of the coagulation failure in obstetrics is: September 2012
**Core Concept**
The question is testing the understanding of coagulation disorders in obstetrics, specifically the most common cause of coagulopathy in this context. **Disseminated intravascular coagulation (DIC)** is a key concept here, which involves the widespread activation of the coagulation cascade leading to both thrombosis and bleeding.
**Why the Correct Answer is Right**
The most important cause of coagulation failure in obstetrics is **amniotic fluid embolism (AFE)**. AFE occurs when amniotic fluid enters the maternal circulation, triggering a massive activation of the coagulation cascade. This leads to the formation of thrombi in small blood vessels, consumption of clotting factors, and ultimately, DIC. The pathophysiology involves the activation of **factor XII**, which initiates the intrinsic pathway of coagulation, and the release of **tissue factor**, which activates the extrinsic pathway.
**Why Each Wrong Option is Incorrect**
* **Option A:** While **severe preeclampsia** can cause coagulopathy, it is not the most common cause of coagulation failure in obstetrics.
* **Option B:** **Trauma** can lead to coagulopathy, but it is not the primary cause in the obstetric setting.
* **Option C:** **Inherited coagulopathy** is a rare cause of coagulation failure in obstetrics.
**Clinical Pearl / High-Yield Fact**
Remember the **"4Ts"** mnemonic for diagnosing DIC: **T**ime to diagnosis, **T**issue factor release, **T**hrombocytopenia, and **T**hrombosis.
**Correct Answer: A. Amniotic fluid embolism.**