By Mayo Clinic staff
Your doctor may try to rule out other causes of swelling in order to arrive at a diagnosis of lymphedema. Swelling can have many causes, including a blood clot or an infection that doesn't involve your lymph nodes.
If you're at risk of lymphedema — for instance, if you've recently had cancer surgery involving your lymph nodes — your doctor may assume you have lymphedema based on your signs and symptoms.
If the cause of your lymphedema isn't as obvious, your doctor may order imaging tests to determine what's causing your signs and symptoms. To get a look at your lymphatic system, your doctor may use an imaging technique, such as:
- Radionuclide imaging of your lymphatic system (lymphoscintigraphy). During this test you're injected with a radioactive dye and then scanned by a machine. The resulting images show the dye moving through your lymph vessels, highlighting areas where the lymph fluid is blocked.
- Magnetic resonance imaging (MRI). This scan gives your doctor a better look at the tissues in your arm or leg. He or she might be able to use an MRI to see characteristics of lymphedema.
- Computerized tomography (CT). A CT scan produces images of your arm or leg in cross sections.
- Doppler ultrasound. This variation of the conventional ultrasound assesses blood flow and pressure by bouncing high-frequency sound waves (ultrasound) off red blood cells.