## **Core Concept**
The patient presents with symptoms suggestive of pleural effusion, which is a common complication in patients with nephrotic syndrome. Nephrotic syndrome can lead to hypoalbuminemia, which decreases the oncotic pressure and can cause fluid accumulation in the pleural space. The next best step is to confirm the diagnosis of pleural effusion.

## **Why the Correct Answer is Right**
The correct answer, **Chest Ultrasound (C)**, is the most appropriate next step for detecting pleural effusion. Chest ultrasound is highly sensitive and specific for detecting pleural effusions, even small ones. It is particularly useful in patients with nephrotic syndrome who may have a high risk of fluid overload and pleural effusions. Ultrasound can guide thoracentesis if needed and helps in assessing the nature of the effusion.

## **Why Each Wrong Option is Incorrect**
- **Option A: Chest X-ray** is often the first imaging done for respiratory symptoms but is less sensitive than ultrasound for detecting small pleural effusions. It can show indirect signs but is not as definitive.
- **Option B: CT Thorax** provides detailed images and can detect small effusions but involves radiation and is typically not the first line for suspected pleural effusion due to its cost and radiation exposure.
- **Option D: MRI Chest** is not routinely used for detecting pleural effusions due to its high cost, limited availability, and lesser utility compared to ultrasound or CT for this specific purpose.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that in patients with nephrotic syndrome, the presence of pleural effusion often indicates significant fluid overload. **Chest ultrasound** is a bedside tool that can quickly and accurately diagnose pleural effusions, making it an invaluable tool in acute settings.

## **Correct Answer: C. Chest Ultrasound**