## **Core Concept**
The patient's symptoms of acute chest pain worsened by breathing (pleuritic chest pain) suggest a condition affecting the pleura or lung parenchyma. Bedridden patients are at risk for venous thromboembolism (VTE), which includes deep vein thrombosis (DVT) and pulmonary embolism (PE). Pulmonary embolism is a critical condition that can present with pleuritic chest pain.

## **Why the Correct Answer is Right**
The correct answer, **D. CT Pulmonary Angiography (CTPA)**, is helpful in diagnosing pulmonary embolism (PE), a condition that can cause acute chest pain worsened by breathing. CTPA involves injecting contrast into the patient's veins and then taking images of the lungs using computed tomography. It directly visualizes the pulmonary arteries and can show emboli (clots) within them, confirming the diagnosis of PE.

## **Why Each Wrong Option is Incorrect**
- **Option A:** While a **Chest X-ray** can provide some information about lung and heart conditions, it is not sensitive or specific for diagnosing pulmonary embolism. It might show nonspecific findings or sometimes the "Westermark sign" or "Pleural effusion," but it is not diagnostic.
- **Option B:** An **Echocardiogram** can show signs suggestive of pulmonary embolism indirectly, such as right heart strain, but it does not directly visualize the pulmonary arteries or emboli. It's useful in assessing cardiac causes of chest pain and hemodynamic instability but not the first choice for diagnosing PE.
- **Option C:** A **Ventilation-Perfusion Scan (V/Q Scan)** can be used to diagnose PE, especially when CTPA is contraindicated. However, it's generally not the first line due to its lower specificity compared to CTPA and the higher prevalence of intermediate probability results, which can be inconclusive.

## **Clinical Pearl / High-Yield Fact**
A critical clinical pearl is that **pulmonary embolism can present with pleuritic chest pain**, especially if the embolus affects the lung periphery or causes pulmonary infarction. The **Wells score** and **Revised Geneva score** are clinical prediction rules that can help estimate the probability of PE in patients.

## **Correct Answer: D. CT Pulmonary Angiography (CTPA).**