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

In most cases, seromas are harmless, and doctors let them heal naturally. They 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 following 150 participants found that 49% of the patients experienced a seroma after breast surgery. Another study found that 20% of the participants 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 common in the breast area of people who have undergone surgery 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 the 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 factors can increase the likelihood of a seroma forming. These include:

  • 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

How do seromas develop?

Seromas tend to appear 7–10 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 decrease the likelihood of a seroma developing.

Seromas form lumps under the skin. These 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: This is 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 may need to be drained because they can be painful, lead to scarring, and cause infection.
  • Lymphocele: This refers to an abnormal buildup of lymphatic fluid following a surgical procedure.
  • Abscess: This is 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 a space between organs.

Most seromas heal naturally. They are usually reabsorbed into the body within 1 month, although this can take up to 1 year.

In more severe cases, it can take up to 1 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 that 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 increase drainage, depending on the area affected.

When to contact a doctor

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If the area is sore, warm, red, or swollen, a person should seek guidance from 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 if the symptoms worsen, a person should contact 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 likelihood 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 individuals, 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 not all patients develop seromas.

Typically, seromas form right after surgery when drains are not used. A seroma can still occur up to 1 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 from forming.

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

After a mastectomy, a 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 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 if any other complications develop, patients should contact a doctor. People undergoing surgery should be aware of the signs and symptoms.