Hard Lump Under Incision After Surgery: Causes, Symptoms, Diagnosis, Treatment

A hard lump that develops under an incision from surgery is known as a seroma. It results from fluid accumulation in a place where an organ or tissue has been removed. In most cases, seromas are surgical complications but can also develop after an injury. Serum is a fluid that takes part in fighting pathogens in the body. After surgery, the fluid sometimes leaks from damaged lymphatic or blood vessels. Doctors place drainage tubes to control fluid accumulation after surgery. Seromas can form immediately after surgery or sometime after the drainage tubes have been removed.

What causes a seroma lump under incision after surgery?

It is uncommon to develop a seroma after a minor surgery. Most form when an organ or large portions of tissues have been removed. Most cases are reported after breast cancer surgery. Other types of surgeries that can give rise to a seroma include:

  • Plastic surgeries
  • Hernia repair surgeries
  • Breast implant or reduction surgeries
  • Liposuction

Risk factors include:

  • Some drugs such as tamoxifen
  • Large breasts
  • Old age
  • Large or multiple tumors
  • Recent surgery

It is not normal to have an empty dead space in the body under the skin. It is thought that the immune system responds by creating a seroma to fill the space left after an organ or tissue has been removed. There are reasons to also associate seromas with damaged lymphatic vessels.

Symptoms of seroma lump under incision

Most seromas develop 7-10 days after surgery. They appear as fluid-filled, swollen lumps under the skin. The flooded fluid is white or yellowish in color.

It can take up to months or years for a seroma to resolve on its own. In some cases, scar tissue will form and create a hard knot under the skin. This knot will persist even after the accumulated fluid has been reabsorbed. Below are some lumps that can be confused with a seroma:

  • Hematomas – these are abnormal collections of blood under the skin. Hematomas are common after injury. A hard lump on testicle after vasectomy can, for example, be caused by a hematoma. Such a lump under skin on forearm on the other hand can appear after being hit with a blunt object. In most cases, color discoloration will accompany a hematoma. Rarely is treatment required. Note that hematomas do not involve damage to outer covering skin layer.
  • Abscess – an abscess is a pus-filled lump that forms under the skin. Bacteria can enter the skin through open wounds or cracks. A blister lump on vaginal lip caused by an STD is, for example, a perfect entry point for bacteria. Some abscesses develop from large boils. They are usually very painful and appear with other signs of infection.

Diagnosis, treatment and prevention for seroma lump after surgery


Diagnosis is done by physical examination and checking the symptoms. If you recently had an extensive surgery and have developed a swollen or tender lump that feels like a large cyst, it most likely is a seroma.

A biopsy may be taken if signs of infection are present.


Minor seromas do not require treatment. The body will naturally absorb back the leaked fluid. This can take a couple of weeks or months.

Large or painful seromas can be managed with pain relievers and anti-inflammatory medications. These will not hasten the recovery process but will put you at ease.

If medications are not helpful, the lump can be drained or removed entirely. Drainage involves your doctor inserting a needle and draining the fluid with a syringe. An entire removal involves performing a minor surgery to get rid of the lump.


If for example you are going for a tummy tuck surgery, consider losing some weight first. This will reduce the amount of tissue that is required to be removed surgically.

Doctors also use compression garments to hasten recovery. Most patients are directed to wear the garments for at least two weeks. You can ask your doctor about them before or after the operation. If the surgery involves the breasts, wearing tight bras can help.

It is also likely that drainage tubes will be inserted after surgery. They work by collecting any fluid building up in the area. Ask your doctor about how you can get the most out of the drainage tubes and the number of days you will be required to have them on.

Nowadays, doctors are using techniques that will result in the least dead space possible. This ensures that even if a seroma will develop, it will not be large enough to cause complications.

Remember to keep the surgical site very clean. Infection is a common and unfortunately very risky complication.

Before the surgery, it will help if you can discuss with your doctor about the chances of developing a seroma. For your part, inform your doctor if you have a history of developing seromas. After that, you can weigh the benefits to decide if the surgery is necessary or not.

Possible complications of a seroma after surgery

Large seromas can slow down recovery from surgery. They also pose a higher risk of getting infected. In some patients, follow-up treatments such as for cancer may be delayed by the presence of a large seroma. Signs of infected seroma include:

  • Fever
  • Chills
  • High pulse rate
  • Pain
  • Tenderness and swelling
  • Pus or bloody discharge
  • Confusion

When to see a doctor

It is common for fluid to build up after surgery. This doesn’t guarantee that a seroma will always develop after surgery. See your doctor if:

  • Fluid accumulation gradually increases rather than subside
  • Swelling occurs and spreads to nearby areas
  • You experience pain or pressure on the surgical site
  • Signs such as skin redness, tenderness and warmth develop
  • Fluid drains from the surgical site
  • You develop a rapid heartbeat rate
  • Pus forms or a bad smell comes from the surgical site

Depending on where the surgery occurred, lymph nodes may swell in different locations. A facial reconstruction surgery can, for example, lead to a lump on jaw line under skin. An infected seroma after a hernia repair may lead to a lump in the groin area. All these are signs of wide spread infection and should be taken seriously.