**Question:** Most common symptom in Pulmonary embolism is -

A. Shortness of breath
B. Pleuritic chest pain
C. Hemoptysis
D. Pleuritic chest pain without hypoxia

**Core Concept:**
Pulmonary embolism (PE) is a life-threatening condition characterized by the blockage of pulmonary arteries in the lungs due to blood clots. The clinical presentation can be divided into acute and subacute categories based on the time since the clot formation. The most common symptoms in acute PE are related to the embolus's size, location, and the resulting pulmonary artery obstruction.

**Why the Correct Answer is Right:**
The most common symptom in acute pulmonary embolism is **Shortness of breath (Dyspnea)**, which is primarily due to the increased workload on the right ventricle and the subsequent decrease in cardiac output and blood flow to the lungs. The increased right ventricular afterload (obstructed pulmonary arteries) leads to a compensatory increase in right ventricular contractility, which causes fatigue and failure.

**Why Each Wrong Option is Incorrect:**

**B. Pleuritic chest pain:** Pleuritic chest pain is typically seen in conditions like pleurisy, pneumonia, or pleural effusion. In PE, pleuritic pain is less common because the embolus is lodged in the pulmonary artery, and the pain is transmitted to the brain, resulting in a diagnosis of PE.

**C. Hemoptysis:** Hemoptysis is the expectoration of blood-streaked mucus from the respiratory tract. It is a symptom of lung parenchymal hemorrhage or infection and is not the most common symptom in acute PE.

**D. Pleuritic chest pain without hypoxia:** Pleuritic pain without hypoxia is more likely to be seen in pleural effusion or pleurisy rather than PE. Hypoxia is a common sign in PE due to the decreased oxygenation from the obstructed pulmonary arteries.

**Clinical Pearls:**
1. If a patient presents with pleuritic chest pain, it should raise suspicion for PE, but it is not the most common symptom.
2. Hypoxia is a key sign in pulmonary embolism due to the decreased oxygenation from obstructed pulmonary arteries.
3. The correct answer, dyspnea, is the most common symptom in acute PE, primarily due to increased workload on the right ventricle and decreased pulmonary perfusion.

**Correct Answer Explanation:**
The correct answer, dyspnea (shortness of breath), is the most common symptom in acute PE, primarily due to increased workload on the right ventricle and decreased pulmonary perfusion. The embolus obstructs the pulmonary arteries, leading to a decrease in pulmonary perfusion and oxygenation, which contributes to the patient's symptoms.