Seroma - Medical Definition

Seromas are Common After Breast Surgery

Seroma and Breast Brachytherapy
Seromas May Form During or After Breast Brachytherapy. Credit: Art © Pam Stephan

A seroma is a pocket of fluid that typically forms after an injury, most commonly after a surgical procedure. Seromas are filled with serous fluid - a pale yellow, transparent fluid that contains protein, but no blood cells. Seromas are particularly common after breast surgery. While they are common, surgeons and patients prefer to avoid this complication.

  • Pronunciation: seh-RO-muh

Typically, seromas are reabsorbed by the body in a few days to a few weeks.

However, if a seroma persists, it can eventually become a hard, partially calcified scar. Because of this, if it appears that a seroma is not clearing up normally, the doctor may insert a fine needle into the fluid pocket to drain it.

Seromas After Breast Surgery

Seromas are common after breast cancer surgery, including in modified radical mastectomy, breast conserving therapy (lumpectomy), and lymph node removal. They form in the dead space of the post-mastectomy skin flap. Statistics report the incidence at 15-18%. It usually resolves within a few weeks, but it can take a few months to clear up. But it can cause discomfort and it can stretch the skin and cause it to sag. At times the development of a seroma can prolong your hospital stay after surgery.

Symptoms and Management of a Seroma After Breast Surgery

The symptoms of a seroma appear a week or more after surgery and after any drains have been removed.

You feel a swollen area and it may feel like there is liquid under the skin. It can become painful.

You should discuss the symptoms with your health care team to see if they want you to come in to have it drained. This is a simple office procedure that may be performed by your doctor or a nurse or physician's assistant.

The health care provider inserts a needle through the skin into the seroma and draws off the excess fluid.

Check the area around your surgical site for signs of infection. If it becomes red, swollen or has a discharge you should contact your doctor immediately to get treatment. If the swelling increases, it could be a sign of lymphedema developing, and this will need to be managed by your health care team.

Prevention of Seromas

Surgeons have been studying which surgical techniques are best to reduce the incidence of seromas. Electrocautery used in surgery to prevent blood loss seems to increase the risk of seroma as it causes heat damage to the tissues. They have to balance the risk of seroma with the effectiveness of it in preventing bleeding.

Compression bandages used to be used to prevent seroma but are rare now. Short term use of drains reduces the incidence of seroma. A closed suction drain or a low suction drain appear to have good results in preventing seromas or reducing their size and duration.

All of these factors are under the control of the physician.

If you have questions about seromas, discuss it further with your doctor before and after surgery. It is good to know what the purpose is of drains and other measures that will be used.


Wong K, Truong PT, Kader HA, et al. Consistency in seroma contouring for partial breast radiotherapy: Impact of guidelines. Int J Radiat Oncol Biol Phys 66 (2): 372-6, doi:10.1016/j.ijrobp.2006.05.066, PMID 16965989

Seroma (Fluid Build-Up), January 9, 2015,

Sanjitha Sampathraju and Gabriel Rodrigues "Seroma Formation after Mastectomy: Pathogenesis and Prevention," Indian J Surg Oncol. 2010 Dec; 1(4): 328–333.

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