Lymphoedema is a chronic condition where swelling develops because the body’s lymphatic system is not able to drain fluid properly. The lymphatic system is a vital part of the immune system and circulatory system. It helps clear extra fluid, waste products, and proteins from tissues and returns them to the bloodstream. When this system becomes blocked, damaged, or underdeveloped, fluid builds up in the tissues. This causes swelling, heaviness, tightness, and sometimes changes in the skin.
Lymphoedema is a gradual condition, and early recognition and treatment make a major difference. Although it is a lifelong condition, many people achieve excellent control of symptoms with a combination of therapy and, in selected cases, surgery.
Causes of Lymphoedema
Lymphoedema can be broadly divided into primary and secondary forms.
Primary Lymphoedema
Primary lymphoedema occurs when parts of the lymphatic system have not developed normally. This can include lymph vessels that are too narrow, too few in number, or poorly formed lymph nodes. Many people are born with these changes, but swelling might not appear until puberty, pregnancy, or even adulthood. People with primary lymphoedema may notice swelling beginning in the feet or lower leg, a feeling of heaviness or aching, and gradually increasing difficulty with movement.
Secondary Lymphoedema
Secondary lymphoedema is much more common and happens when a previously healthy lymphatic system becomes damaged. The most common causes include:
- Surgery involving lymph node removal (e.g., breast cancer, melanoma, gynaecological cancer).
- Radiation therapy, which can scar and stiffen lymphatic channels
- Trauma or burns
- Recurrent cellulitis, which damages lymph vessels permanently
- Venous disease, where chronic back-pressure affects lymph drainage
- Obesity, which physically compresses and impairs the lymphatic system
In some people, several of these factors combine to increase the risk.
Progression of Lymphoedema
The lymphatic system normally collects protein-rich fluid from the tissues and returns it to the bloodstream. When the system becomes impaired: Lymphatic flow slows down or stops, causing fluid to accumulate in the tissues. Inflammation develops as the body reacts to this stagnant fluid. Over time, the tissues undergo fatty and fibrotic changes, meaning they become firmer, thicker, and harder to compress. The limb becomes more prone to infection, especially cellulitis, because the immune cells cannot move effectively through the swollen tissue. This cycle can worsen without treatment. Early-phase lymphoedema may feel soft and pitting, while late-phase lymphoedema becomes firm and difficult to indent, which is why patients with long-standing lymphoedema often develop a heavier, more fibrous limb.
Investigations
Although lymphoedema can often be diagnosed through a clinical examination, imaging studies provide useful information about the underlying structure and function of the lymphatic system.
- Ultrasound
Ultrasound is usually the first test performed. It helps rule out other causes of swelling such as blood clots, varicose veins, cysts, or soft-tissue masses. It may show changes typical of lymphoedema, such as thickened skin and increased soft-tissue fluid. - MRI
MRI provides highly detailed images of the soft tissues. In lymphoedema, it can show fluid accumulation, changes in fat distribution, and tissue thickening. MRI is helpful when planning surgery or when the cause of swelling is unclear. - Lymphoscintigraphy
This nuclear medicine scan looks at how well lymph fluid drains from the limb. A small tracer is injected under the skin, and a special camera tracks how it moves through the lymphatic vessels to the lymph nodes. It can show blocked pathways and slow or delayed drainage. Lymphoscintigraphy is useful for an overall diagnosis but does not show very small lymphatic vessels in detail. - ICG Lymphangiography
ICG lymphangiography is now one of the most important tools for assessing lymphoedema, especially before surgery.
What is ICG Lymphangiography?
ICG (indocyanine green) lymphangiography is a minimally invasive procedure that creates a real-time map of the lymphatic vessels just beneath the skin using a special near infrared camera.
Here is what patients can expect:
- Tiny injections of fluorescent dye are placed just under the skin, usually in the hands or feet. These injections may sting briefly. The dye quickly enters the lymphatic channels.
- A near-infrared camera is used to track the dye as it moves.
Static images are taken after injection at around 10 minutes.
Manual lymphatic drainage (MLD) is then used to shift the dye up the limb over a period of around 45 minutes. - The lymphatic changes and area of lymphatic congestion are marked with a pen and photographs are taken.
This shows which lymph vessels tare working, which are blocked, and where the fluid is leaking or pooling. This imaging allows highly accurate planning for procedures like lymphovenous anastomoses (LVA). The test is generally very safe, with minimal discomfort, and results are available immediately.
