Most Common Type of Pulmonary Embolism: Symptoms, Causes, and Risk Factors

Understanding Pulmonary Embolism: A Sudden and Dangerous Condition

Pulmonary embolism (PE) is a serious medical condition that occurs when a blood clot—typically originating in the deep veins of the legs—travels through the bloodstream and blocks one of the pulmonary arteries in the lungs. This blockage can severely impair oxygen exchange and lead to life-threatening complications if not promptly diagnosed and treated.

The Most Frequent Presentation: Acute Shortness of Breath with Chest Pain

The most common clinical manifestation of pulmonary embolism is sudden-onset dyspnea, or shortness of breath, often accompanied by sharp chest pain. This pain is typically localized to the right side of the chest and tends to worsen with deep breathing or physical exertion. Unlike typical musculoskeletal discomfort, this type of chest pain is directly related to reduced blood flow and oxygenation in the lung tissue.

Key Signs That Signal a Potential PE

One of the hallmark signs of a significant pulmonary embolism is a noticeable drop in blood oxygen levels, known as hypoxemia. What makes this particularly concerning is that the low oxygen saturation often does not improve significantly with supplemental oxygen therapy. This resistance to standard oxygen treatment should raise immediate red flags for healthcare providers and may prompt urgent imaging studies such as a CT pulmonary angiogram to confirm the diagnosis.

Origin of the Clot: Deep Vein Thrombosis and Triggering Events

In the majority of cases, the clot responsible for PE originates from deep vein thrombosis (DVT), especially in the lower extremities. Certain activities can trigger the dislodgement of these clots. For example, when patients with existing DVT become physically active—such as standing up, walking, or moving their limbs after a period of immobility—the shift in venous pressure can cause the clot to break free and travel to the lungs.

Additional risk factors include conditions that increase intra-abdominal pressure, such as severe constipation, straining during bowel movements, or even chronic coughing. These situations elevate venous pressure in the pelvic and leg veins, which can push a stationary clot into circulation. Other high-risk scenarios include recent surgery, prolonged bed rest, pregnancy, and certain clotting disorders.

Beyond the Common Symptoms: Atypical Presentations

While acute dyspnea and pleuritic chest pain are the most recognized symptoms, pulmonary embolism can sometimes present more subtly. Some patients may experience persistent low-grade fever, unexplained fatigue, rapid heart rate (tachycardia), or even fainting spells (syncope). These atypical signs can make diagnosis more challenging, especially in individuals without a clear history of DVT.

Early recognition and intervention are critical. Delayed treatment increases the risk of complications such as pulmonary hypertension, right heart strain, or even sudden cardiac arrest. Therefore, anyone with risk factors who develops sudden respiratory symptoms should seek immediate medical evaluation.