Differential Diagnosis-Infection vs. Lymphedema

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One of the questions we're going to ask is where is the swelling? If it is a lower extremity problem, is the swelling distal to the surgical site? In that case, there may be something wrong with the lymphatic system. If we're seeing a diffusion of lymph fluid, we need to address it. Is the swelling proximal to the surgical site, as in the case of an upper extremity problem? For example, the person who had surgery is elevating their affected hand, and now the diffusion is happening into the wrist and the hand. In that case, we need to do some problem solving to determine the location of the swelling, why is it occurring, and what exactly is going on.

We also want to know the orientation of the surgical site. We want to know if it's parallel to the lymph vessels and if it's working with the lymphatic system. Or, if it's perpendicular to the lymphatic system, it may be cutting some of the lymph nodes. Again, we're going to be seeing lymphedema and a lot of swelling.

What kind of surgical procedure did the patient have? Could lymph nodes have been traumatized during this procedure? It is a common occurrence, especially with things like total knee and total hip replacements. 

Is there a specific pattern of swelling? Essentially, each lymph node controls a territory of skin. If one or a few lymph nodes are traumatized, damaged, or surgically removed, the skin that they serve ends up having the fluid. It's not a generalized fluid; it's specific to the lymph node, or specific to the lymph vessels that got damaged as part of the process.

It's important that we do a differential diagnosis and distinguish infection from lymphedema since both cause swelling. As we learned in school, infection is characterized by rubor, dolor, tumor, and calor. With infection, the skin is red, there is a lot of pain, a lot of swelling, and if you touch the skin, it's hot. With lymphedema, we have a different clinical picture. If you look at the skin, it is usually a normal color. Lymphedema is not usually painful. The swelling of lymphedema is very different than the swelling that you see with infection. This swelling is either pitting or non-pitting. You get pitting edema if you get a buildup of lymph fluid between the body cells. Over a period of time, if the fluid remains, it changes into a gel-like substance, and it becomes harder non-pitting edema. Also with lymphedema, when you touch the skin, it feels like a normal body temperature, it's not hot.