What Is It, Causes, Treatment, and More

Author: Nikol Natalia Armata

Editors: Alyssa Haag, Józia McGowan, DO, FACOI, FNAOME, CS

Illustrator: Abbey Richard

Copyeditor: Joy Mapes

Modified: 4 Jan 2024

What is a seroma?

A seroma, one of the most common potential complications after surgery, refers to the accumulation of uninfected and clear (i.e., serous) fluid under the skin. Seromas are usually found near the site of a surgical incision and can form soon after surgery or, sometimes, weeks later. 

What causes a seroma?

Usually, seromas develop in places where tissue has been removed with surgery. Dead space, or a remaining empty cavity in between tissues, may form as a result of improper healing of the surgical wound. Damage to neighboring lymphatic vessels during surgery can cause leakage of serous fluid into the dead space, resulting in seroma formation. 

Abdominal wall reconstructions, hernia repairs, and removal of masses, such as thyroid tumors, require extensive separation of multiple layers of skin and tissue, potentially resulting in the postoperative formation of seromas. Similarly, fluid can accumulate after various plastic surgeries, such as abdominoplasties (i.e.,  tummy tucks), during which excess fat and skin are removed from the abdomen, and breast reconstruction surgeries. Seroma formation commonly occurs in individuals who undergo breast removal surgery, whether partial breast tissue removal (i.e., lumpectomy) or total breast tissue removal (i.e., mastectomy). Liposuction, a procedure to remove large amounts of fat tissue, and body contouring, which redistributes fat tissue, also increase the risk of dead space and seroma formation. Finally, seromas can appear weeks after surgery when drainage tubes, used to prevent fluid accumulation under the skin, are removed earlier than recommended.

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What does a seroma look like?

A seroma can typically be easily identified during physical examination, generally presenting at the site of surgical incision as a soft, swollen lump that discharges clear fluid. When physical examination cannot confirm the diagnosis, a bedside ultrasound can provide better visualization of the seroma. If the seroma is large in size, the area surrounding it may become inflamed and painful. If the seroma becomes infected, it may appear red and feel very tender and warm to the touch. Infected seromas often lead to the formation of an abscess, or a collection of pus. 

How are seromas treated?

Treatment for seromas largely depends on the severity of the fluid collection. Often, the body will naturally reabsorb a seroma, resolving the issue without treatment. Even when small seromas do not fully reabsorb, they typically do not have any significant impact on an individual's health and may not require treatment either. On the other hand, more severe cases may require further medical care. If the affected area increases in size or presents with any sign of infection (e.g., redness, pus), a healthcare professional may drain the seroma using a needle and a syringe, a procedure known as aspiration. Aspiration of clear fluid not only confirms the diagnosis but can also alleviate pain. This procedure may be performed more than once if the first aspiration does not completely drain the seroma. Additionally, compression bandages can be applied to the affected area in order to minimize lymphatic leakage and prevent reaccumulation of the fluid. In rare instances, if the seroma persists despite trying non-surgical treatments, surgical intervention may be necessary.  

Do seromas go away on their own?

Small seromas often reduce in size and go away on their own. However, if seromas grow larger or appear infected, they may need to be treated by a healthcare professional. Larger seromas usually require treatment by a healthcare professional. 

What happens if a seroma is left untreated?

If a sizable seroma is left untreated for a long period of time, a thin cover of tissue called a fibrous capsule can develop around the mass. The capsule can make it more difficult for the seroma to be completely drained, and therefore, allow fluid to continue accumulating rapidly. In such cases, frequent drainage is usually necessary, and surgical removal is often suggested. Moreover, an encapsulated seroma poses an increased risk of infection, which may result in the seroma becoming an abscess. If there is any sign of infection -- such as high fever, redness, or pain at the affected area -- seeking medical advice is advised, as antibiotics and drainage of the abscess may be necessary in order for the symptoms to improve.

What are the most important facts to know about seromas?

A seroma refers to the accumulation of clear fluid under the skin, typically near the site of a surgical incision. A seroma usually forms after some type of reconstructive surgery, during which dead space is created. Seromas vary in size and presence of inflammation, but they typically appear as a soft, swollen lump. Small seromas often regress into the body on their own; those that remain can be aspirated using a needle and syringe. If a seroma persists, surgical removal may be considered. Large, untreated seromas pose an increased risk of infection, and they may develop a fibrous capsule, complicating drainage.

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Related links

Abdominal hernia
Breast cancer

Resources for research and reference

Goldman, A., Wollina, U., França, K., Tchernev, G., & Lotti, T. (2018). Chronic encapsulated seroma persisting for three years after abdominoplasty and a successful surgical solution. Open Access Macedonian Journal of Medical Sciences, 6(1): 82-84. DOI: 10.3889/oamjms.2018.051

National Cancer Institute at the National Institutes of Health. (n.d.). Seroma. In NCI dictionary of cancer terms. Retrieved February 1, 2021, from

Turner, E. J., Benson, J., & Winters, Z. (2014). Techniques in the prevention and management of seromas after breast surgery. Future Oncology, 10(6): 1049-1063. DOI: 10.2217/fon.13.257 

Hooker, E. (2020). Complications of general surgical procedures. In J. Tintinalli, O. J. Ma, D. Yealy, G. Meckler, J. S. Stapczynski, D. Cline, & S. Thomas (Eds.), Tintinalli's emergency medicine: A comprehensive study guide (9th ed.). McGraw-Hill. 

Janis, J., Khansa, L., & Khansa, I. (2016). Strategies for postoperative seroma prevention. Plastic and Reconstructive Surgery, 138(1): 240-252. DOI: 10.1097/prs.0000000000002245 

St George’s University Hospitals. (2021). Seroma aspiration. Retrieved February, 2021, from 

Zheng-Pywell, R., & Chu, D. (2020). Postoperative complications. In G. Doherty (Ed.), Current diagnosis & treatment: Surgery (15th ed.). McGraw-Hill.