What is meant by swelling?
Swelling means that a body part or tissue becomes larger. Fluid accumulation is called edema, but swelling can also be due to blood, inflammation, infection, or a tissue change.
Edema can be soft and leave a dimple when pressed, but this is not always the case. Over time, lymphedema can become firmer and the skin can change.
Location and symmetry are key. Swelling in one leg, both legs, a face, or a single joint has different likely causes.
Common causes of swelling
Local swelling often occurs after injury, overuse, insect bites or infection. A sprain can cause bleeding and inflammation, while arthritis causes swelling in and around the joint.
Swollen legs on both sides can be caused by venous insufficiency, heart failure, kidney or liver disease, medications, or prolonged sitting. Unilateral swelling can be caused by injury, infection, blood clots, or impaired lymph transport.
Lymphedema is caused by impaired transport of lymph fluid. Also read about lymph nodes and their role in the lymphatic system.
When is swelling a warning symptom?
Seek emergency medical attention if you experience sudden swelling of your face, tongue, or throat, especially if you have difficulty breathing or swallowing. This may be an allergic reaction.
Sudden unilateral leg swelling with pain, warmth, or redness needs to be evaluated for a blood clot. Swelling along with chest pain or shortness of breath should be evaluated urgently.
A red, warm, rapidly increasing swelling with a fever may be due to infection. Discoloration, cold skin, or severe pain may indicate circulatory problems.
Call 112 if you have swelling in your face or throat with difficulty breathing. Seek emergency care if swelling is accompanied by chest pain, severe shortness of breath or a rapidly worsening condition.
How is swelling investigated?
The healthcare provider will assess when the swelling started, whether it is one-sided, whether it varies throughout the day, and what medications you are taking. Your skin, circulation, heart, lungs, abdomen, and lymph nodes may need to be examined.
Blood and urine tests can provide information about the kidneys, liver, protein levels, inflammation and heart strain. Weight and blood pressure can be monitored over time.
Ultrasound is used when a blood clot is suspected. The heart can be assessed with an ECG and ultrasound, while local swelling sometimes requires ultrasound, X-ray, CT or MRI.
What imaging diagnostics are used for swelling?
Ultrasound is often the first-line method for suspected blood clots, fluid-filled lesions, or superficial nodules. X-rays are used for skeletal injuries and can show some signs of heart or lung disease.
CT and MRI are used when deeper tissues or organs need to be assessed. The choice is guided by whether the question concerns vessels, soft tissue, bones, abdominal organs or inflammation.
A general MRI is not a standard investigation for swelling. The correct test is chosen based on the most likely mechanism.
What can help with harmless swelling?
For mild leg swelling after sitting, movement, elevation and breaks can help. Compression stockings may be appropriate for some but should be used after assessment if circulation is uncertain.
In the event of an injury, appropriate loading and short-term elevation are often useful. Avoid hard massage of a suddenly swollen and painful leg before a blood clot has been ruled out.
Do not change fluid intake or diuretics on your own. Treatment should be directed at the cause.
Differences between venous swelling, lymphedema and inflammation
Venous swelling in the legs is often more noticeable during the day and may decrease after a night's rest or elevation. The skin may become discolored and tight over time. Treatment may include movement, compression, and addressing underlying vein problems.
Lymphedema can start out soft but often becomes firmer over time. It can occur after surgery or radiation therapy, but also for other reasons. Specialized lymphatic therapy, skin care, and compression can reduce discomfort and the risk of infection.
Inflammatory swelling is often warm, tender, and sometimes red. In the case of injury, swelling is part of the healing process, while infection requires treatment. It is not always possible to distinguish the conditions by appearance alone.
Measuring circumference or monitoring body weight can be useful for recurrent swelling, but the results need to be interpreted in context. For example, rapid weight gain along with shortness of breath may indicate fluid retention and should be evaluated.