A seroma is the buildup of fluids in a place on the body where tissue has been removed. They often occur as a complication of surgery but can also develop after an injury.

In most cases, seromas are harmless and are allowed to heal naturally. Seromas are not related to cancer cells and pose no increased risk or concern. However, they can cause discomfort and lead to a longer hospital stay after surgery.

One study of 158 participants found that 35 percent of patients experienced a seroma after surgery for breast cancer. Another found that 20 percent of women had seromas that were visible on a CT scan 6 months after surgery.

A seroma is a fluid-filled pocketShare on Pinterest
A seroma is a fluid-filled pocket that can develop after breast surgery.

The exact causes of seromas are not clear, but they are commonly seen in the breast area of women after surgeries to treat breast cancer.

Other procedures that can cause seromas include:

  • breast reduction
  • breast implant
  • breast biopsy
  • plastic or cosmetic surgery
  • plastic reconstructive surgery

The formation of seromas is the body's response to dead space within tissue that was attached to something before surgery.

Surgeons expect seromas to develop after surgical procedures or where any skin break occurs.

Risk factors

Some risk factors can increase the chances of a seroma forming:

  • age
  • breast size
  • presence and number of cancerous nodes in the armpit
  • previous biopsy surgery
  • use of drugs called heparin or tamoxifen
  • body mass index (BMI)

How do seromas develop?

Seromas tend to appear 7 to 10 days after surgery, after drainage tubes have been removed. Areas involved in the surgery may develop spots that are swollen and feel like liquid under the skin.

Surgery causes damage to the blood and lymph vessels and surrounding tissue. An inflammatory response occurs, and the severed vessels and tissues will produce clear fluid in response.

This is why there is pain and swelling after surgery. In some cases, the fluid forms a pocket, which leads to the formation of a seroma.

Carrying out surgery in a way that reduces the risk of leaving dead space can also reduce the chance of a seroma developing.

Seromas form lumps under the skin. They are filled with a yellowish-to-white fluid called serous fluid. This is the same fluid commonly seen in blisters and fresh cuts.

The lumps can be tested to determine whether they contain serous fluid instead of pus, blood, or another fluid.

Similar conditions to seromas

There are conditions that are sometimes mistakenly identified as seromas.

  • Hematoma: A collection of blood in dead space in the body. It is generally caused by a small blood vessel opening up while someone is recovering from surgery. Hematomas must be drained because they can be painful, lead to scarring, and cause infection.
  • Lymphoceles: The abnormal buildup of lymphatic fluid following a surgical procedure.
  • Abscess: A painful collection of pus that is generally due to a bacterial infection. Pus is a thick fluid that contains white blood cells, dead tissue, and germs. Most abscesses form under the skin but can occur inside the body in an organ or space between organs.

Most seromas heal naturally. They are usually reabsorbed into the body within a month, although this can take up to a year.

In more severe cases, it can take up to a year for them to be reabsorbed, or they can form a capsule and remain until they are removed surgically. The area may experience hardening once the seroma heals.

Heat can be applied to the area to help it heal more quickly. A heating pad or hot compress can be applied for about 15 minutes every few hours. This helps with fluid drainage while providing additional comfort to the incision area.

People should make sure that the heat is not too hot and the compress is not left on the area for a long time. Too much heat can lead to additional fluid buildup in the seroma. Keeping the area elevated may also help to increase drainage depending on the area affected.

When to see a doctor

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If the area is sore, warm, red, or swollen, you should see a doctor.

The seroma may take a few weeks to absorb on its own. Letting a seroma absorb on its own is the best way to heal naturally as long as no complications arise.

If the seroma does not improve or the symptoms worsen, the person should tell a doctor.

A doctor may need to drain the seroma if:

  • it gets bigger
  • the amount of fluid seems to be increasing
  • there is no improvement
  • it puts excessive pressure on the area of surgery or injury, the skin, or an organ
  • it becomes painful
  • there are signs of infection or inflammation, such as redness, warmth, or tenderness

Seromas can increase the chances of a surgical site infection, so it is important to monitor them carefully.

Depending on the severity, a seroma may have to be drained more than once.

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Fine needle aspiration can be used to draw off fluid.

A process called fine-needle aspiration is sometimes used to drain the area. It is also a good way to monitor the volume of fluid leakage.

If seromas become a recurring problem and have to be drained often, one option is to fit a drainage tube to keep the area clear.

Drainage increases the risk of infection and should be performed in a clean environment by a medical professional.

Prolonged drainage can increase the risk of infection and further delay the healing process.

Risks of surgery

In some patients, the best option may be to leave the seroma alone. For cancer patients, one concern with seromas is that they can sometimes delay additional cancer treatments.

Seromas are now often considered a side effect of surgery rather than a complication, but all patients do not develop seromas.

Typically, seromas form right after surgery when drains are not used. A seroma can still occur up to a month after surgery and the removal of the drains.

Though seromas are a common complication of surgery, there are some things that can be done to help prevent them from forming.

Closed suction drainage for several days is one of the main options to help reduce seroma formation. New techniques attempt to reduce the amount of dead space created to help prevent seromas forming.

After surgery, a tight bandage is usually applied to the treatment area. Dressings help to keep the area clean and free from bacteria. They also keep it from being stretched and reduce fluid collection.

After a mastectomy, lumpectomy, or even a breast reduction is performed, the patient is told to wear a tight bra to put pressure on the surgical site. This helps to lessen the risk of fluid leaks and speeds up healing.

Patients are recommended to wear compression garments for at least 2 weeks after surgery and to massage the area gently to help move the fluid out.

It is important to keep the wound clean to keep out bacteria and other germs. Preventing infection at the surgery site is another important way of avoiding the formation of seromas.

A mild buildup of fluid is common after surgery and does not necessarily mean a seroma will appear.

Seromas that are infected can be drained and treated with antibiotics or other medicines, and the patient will make a full recovery.

Though most seromas are harmless, patients should pay attention to them. If a seroma becomes extremely large or any other complications develop, patients should contact a doctor. People undergoing surgery should be aware of the signs and symptoms.