What is a Seroma?

Medically Reviewed by Stephanie S. Gardner, MD on May 06, 2023
Written by WebMD Editorial Contributors
3 min read

‌A seroma is a build-up of clear fluid inside the body. It happens most often after surgery. A seroma is not often dangerous, but it can cause pain and discomfort.

If you have a seroma, your doctor or care provider can offer advice or relief. 

A seroma can happen in an organ, tissue, or body cavity. After surgery, fluid may enter the surgical site, especially if the site is a cavity. This fluid is part of your body's natural healing process, which is initiated because your body's tissues need to be healed after surgery.‌

When any injury, including that related to surgery, occurs to a tissue, your body responds with inflammation. This inflammation is what leads to the main fluid build-up.

After surgery, many people are treated using a device like the Jackson Pratt drain to take out the extra fluid while they are healing. Seroma may happen after the drain comes out.

Typically, a seroma may arise about 7 to 10 days after surgery. Sometimes a seroma happens even if you don't have a drain. 

Seroma is most often associated with breast cancer surgery including the following types:

  • mastectomy
  • lumpectomy
  • ‌lymph node removal

Seroma is also a possible complication of other procedures like:

Speak with your doctor or care provider before you have any surgery. A seroma may be a complication even if your type of surgery is not on this list. 

A seroma may cause symptoms at the site of your surgery, including the following:

  • a balloon-like swelling of the skin 
  • ‌a feeling of liquid or obvious movement under the skin

If the seroma is large, its size may cause you discomfort. Although not necessarily cause for alarm, seroma should be looked at by a doctor. 

Many seromas do not need treatment. Often the body will reabsorb the fluid. This usually takes about a month but can take as long as a year. 

Sometimes doctors would advise you to get treatment for the seroma. This treatment will involve needle aspiration — which is draining the fluid with a needle — but this can increase the risk of introducing infection to the area. So, this treatment is only used if the following conditions are observed:

  • the area is free of infection
  • the seroma causes discomfort, pain, pressure, or tightness
  • the seroma impacts function or mobility

A large seroma, even if it is not painful, can badly affect your appearance after the body has healed.

In most cases, a seroma is not an emergency. But you should let your doctor know if you think you have a seroma. 

The following are signs that your seroma has gotten infected:

  • tenderness
  • redness
  • warmth

Tell your doctor if you experience any of these on or near the seroma. Also, tell your doctor if you notice that:

  • the seroma is getting bigger
  • the amount of fluid is increasing
  • the seroma is causing pressure, discomfort, or pain
  • the swelling increases

These all may indicate another medical issue that may require medical attention. 

Even a seroma that does not need treatment can affect your healing journey. According to a 2018 study, in people living with breast cancer, seroma can result in the following:

  • longer recovery
  • discomfort
  • delayed radiotherapy

Because a seroma can directly affect your health including the pace and timeline of your remaining treatment, talk to your care provider about your experiences and symptoms. 

Seroma is often a manageable complication of surgery. Many people need no treatment. Sometimes seroma can get worse and affect your healing and treatment plan. Talk to your medical team about symptoms and reach out to them if you need support.