**Question:** What is the minimum amount of free blood detectable by the FAST (Focused Assessment with Sonography in Trauma) examination?

**Core Concept:** FAST is a rapid ultrasound examination performed in trauma patients to assess for free fluid in the abdominal and thoracic cavities. It is a crucial tool in detecting hemorrhage and guiding clinical management.

**Why the Correct Answer is Right:** The correct answer is D, which states that FAST can detect free blood if it is a minimum of 10 mL. In FAST examination, the presence of free fluid corresponds to a minimum of 10 mL or more. This amount is significant enough to cause hemodynamic instability and clinical symptoms, prompting further evaluation and intervention.

**Why Each Wrong Option is Incorrect:**

A. Inaccurate: The FAST examination aims to detect clinically relevant hemorrhage, not a minimal amount of blood. Detecting less than 10 mL may not lead to clinical intervention or hemodynamic instability.

B. Inaccurate: The FAST examination is performed to detect significant hemorrhage, not based on the presence of blood. A minimal amount of blood does not necessarily indicate a clinical concern.

C. Inaccurate: The FAST examination is used to evaluate for clinically significant hemorrhage, not specifically the amount of blood. Detecting less than 10 mL may not warrant further investigation or intervention.

E. Inaccurate: The FAST examination assesses the presence and impact of hemorrhage, not the absolute volume of blood. Detecting less than 10 mL does not necessarily indicate clinical relevance.

**Clinical Pearl / High-Yield Fact:** The FAST examination is a rapid and non-invasive method to assess for clinically relevant hemorrhage in trauma patients. While the examination focuses on detecting free fluid, the minimum threshold is determined by the potential hemodynamic consequences and clinical implications of the hemorrhage, not the specific volume of blood.

**Correct Answer:** D (10 mL)