Can a blood clot in the lungs strike without leg swelling?

When we think of a blood clot in the leg, we usually imagine a swollen, painful calf. And because most pulmonary embolisms originate from clots in the deep veins of the legs or pelvis, it is natural to assume that leg swelling should come first. But that is not always the case.

A pulmonary embolism can occur without any obvious leg swelling—and sometimes breathlessness or chest discomfort may be the first warning that something is wrong.

Pulmonary embolism, or PE, occurs when a blood clot travels through the bloodstream and blocks an artery in the lungs. The clot often begins as a deep vein thrombosis (DVT) in the leg. However, DVT does not always announce itself with pain, redness or swelling.

A clot may form quietly in the deeper veins of the leg or pelvis. 

Sometimes it produces very few symptoms. In other situations, part of the clot may break away and travel to the lungs before the leg has had time to become noticeably swollen.

This is why the absence of leg swelling should never be used to rule out pulmonary embolism.

Listen to what the body is telling you

The symptoms of PE can vary considerably. Some people experience sudden breathlessness or sharp chest pain, especially while taking a deep breath. Others may simply feel unusually tired, light-headed or notice that their heart is racing.

In a more serious pulmonary embolism, the person may suddenly become very breathless, develop low oxygen levels, faint or experience a significant fall in blood pressure. A large clot can obstruct blood flow through the lungs and place enormous strain on the right side of the heart. In severe cases, the condition can become life-threatening within a short period of time.

Who should be particularly careful?

Blood clots are more likely after major surgery, prolonged bed rest or hospitalisation, serious injury and long periods of immobility. Cancer is another important risk factor. Pregnancy, certain hormonal medications, previous episodes of DVT or PE and some clotting disorders can also increase the risk.

Yet, occasionally, we see patients with pulmonary embolism in whom there was no obvious warning or immediately identifiable trigger.

The good news: PE is treatable

When pulmonary embolism is suspected, doctors assess the symptoms and risk factors and may perform blood tests and imaging. CT pulmonary angiography can directly show clots within the arteries of the lungs. An ultrasound may also be performed to look for DVT in the legs.

Treatment depends on how severely the clot is affecting the patient. 

Many pulmonary embolisms can be successfully treated with blood-thinning medicines.

For selected patients with a large clot burden or significant strain on the heart, more urgent treatment may be necessary. Apart from clot-dissolving medicines, advances in minimally invasive treatment now allow interventional specialists to pass a catheter through a blood vessel into the pulmonary arteries and mechanically remove the clot.

Don't wait for the leg to swell

The most important message is simple: a person does not need to have a swollen leg to have a pulmonary embolism.

If someone develops sudden unexplained breathlessness, chest pain, fainting, low oxygen levels or a sudden drop in blood pressure, pulmonary embolism is one of the conditions that needs to be considered urgently.

Sometimes the body gives us obvious warnings. Sometimes it whispers. Recognising those quieter warning signs—and acting on them early—can save a life.

The author is a consultant - Endovascular Surgery and Interventional Radiology, Manipal Hospital, Goa. 

 

The opinions expressed in this article are those of the author and do not purport to reflect the opinions or views of THE WEEK.