**Question:** Which is not a feature of SVC syndrome?

A. Acute onset
B. Asymptomatic
C. Painless
D. Caused by herniation of liver or spleen into the IVC

**Core Concept:** SVC syndrome (Supreme Vena Cava syndrome) is a clinical condition characterized by compression of the superior vena cava (SVC) by extrinsic compression (e.g., tumor, lymphadenopathy) or intrinsic compression (e.g., thrombus). Clinical features include dyspnea, pleuritic chest pain, edema, and cyanosis.

**Why the Correct Answer is Right:** B. Asymptomatic is incorrect because SVC syndrome is typically an acute onset condition with symptoms that worsen over time. It is rarely an incidental finding on imaging studies.

**Why Each Wrong Option is Incorrect:**

A. Acute onset: Although the syndrome may not be acute, the symptoms are typically sudden in onset due to compression of the SVC.

C. Painless: While some patients may initially present without pain, the syndrome is usually associated with pleuritic chest pain due to SVC compression.

D. Caused by herniation of liver or spleen into the IVC: Herniation of abdominal organs into the IVC is not a feature of SVC syndrome, as the compression is caused by extrinsic factors such as tumors or lymphadenopathy.

**Clinical Pearl:** SVC syndrome is a clinical emergency and requires prompt evaluation and management. It is essential to suspect this condition when encountering patients presenting with acute dyspnea, cyanosis, and swelling in the upper extremities and face.

**Correct Answer:** **D. Caused by herniation of liver or spleen into the IVC.**

***Explanation:** Herniation of liver or spleen into the IVC is a feature of IVC syndrome, not SVC syndrome. SVC syndrome is caused by extrinsic compression of the SVC due to tumors or lymphadenopathy, leading to symptoms such as dyspnea, pleuritic chest pain, edema, and cyanosis. Herniation of abdominal organs into the IVC has a different clinical presentation and management approach, which is not relevant to SVC syndrome.