A 28-year-old pregnant woman develops sudden onset of dyspnea and tachycardia with no other physical findings. Which of the following is the most likely diagnosis?
**Core Concept**
The patient's presentation of sudden onset dyspnea and tachycardia in the context of pregnancy suggests a cardiovascular or respiratory issue. The most likely diagnosis in this scenario is pulmonary embolism (PE), which is a known complication of pregnancy.
**Why the Correct Answer is Right**
Pulmonary embolism occurs when a blood clot (thrombus) breaks loose and travels to the lungs, blocking blood flow and leading to sudden onset of dyspnea, tachycardia, and potentially even hypoxia. In pregnancy, the increased blood volume, venous stasis, and hypercoagulability state increase the risk of developing deep vein thrombosis (DVT), which can eventually lead to PE. The patient's lack of other physical findings makes this a likely diagnosis.
**Why Each Wrong Option is Incorrect**
* **Option A:** Pneumonia is less likely, as it typically presents with fever, cough, and other respiratory symptoms, which are not mentioned in the patient's presentation.
* **Option B:** Cardiac tamponade is a rare condition in pregnancy and would typically present with hypotension, muffled heart sounds, and jugular venous distension, which are not mentioned.
* **Option D:** Acute asthma exacerbation is unlikely, as it would typically present with wheezing, cough, and shortness of breath, which are not mentioned in the patient's presentation.
**Clinical Pearl / High-Yield Fact**
In pregnancy, the risk of pulmonary embolism is increased due to the hypercoagulability state, and patients with a history of DVT or PE should be screened regularly for recurrence.
**Correct Answer:** C. Pulmonary Embolism