Seroma

What a seroma is

During surgery, small blood and lymph vessels are cut, and tissue may be separated, leaving a "dead space". Clear fluid (serum and lymph) leaks into this space and collects. Surgeons often place drains to remove it, and a seroma can form after the drains come out.

Seroma vs hematoma vs abscess

Risk factors

• surgery that creates large spaces: mastectomy, axillary lymph node dissection, abdominoplasty, large hernia repair
• extensive tissue dissection and use of electrocautery
• obesity
• early drain removal or too much early movement of the area
• older age, high blood pressure
• previous radiation

Symptoms

• swelling under or near the incision
• a feeling of fluid moving or a "water balloon" sensation
• pressure, tightness or mild pain
• clear fluid leaking from the incision
• skin may look slightly shiny but not red

Diagnosis

A surgeon usually diagnoses a seroma by examining the area. Ultrasound confirms fluid and its size and distinguishes it from a hematoma, abscess or hernia. Fluid drawn off is clear yellow; cloudy fluid may be sent for culture.

Treatment

• Observation: small, painless seromas are usually absorbed within weeks to a few months.
• Needle aspiration: a surgeon or nurse drains the fluid with a needle, often in the clinic. Seromas commonly refill and may need several aspirations.
• Compression garments or binders after abdominal surgery.
• Reinserting a drain for large, recurrent seromas.
• Sclerotherapy: injecting a substance to seal the space, for persistent cases.
• Surgery to remove the lining (capsule) of a long-standing, encapsulated seroma.
• Antibiotics only if infection develops.

Do not try to drain a seroma yourself; this risks infection.

Seroma after breast surgery

Seromas are among the most common issues after mastectomy and lymph node removal. They are usually managed with aspiration. A late seroma around a breast implant, appearing a year or more after surgery, needs evaluation, because rarely it can be a sign of breast implant-associated anaplastic large cell lymphoma (BIA-ALCL). See breast reconstruction.

Complications

• infection, which can turn a seroma into an abscess (postoperative infection)
• wound breakdown
• delayed healing
• a hard, encapsulated seroma that does not resolve
• discomfort and delay in starting radiation or other treatment

Prevention

Surgeons reduce seroma risk with careful technique, drains, quilting sutures that close dead space, and compression. Following drain care instructions and limiting strenuous activity of the area as advised also help.

Frequently asked questions

What does a seroma feel like?

A seroma usually feels like a soft, squishy swelling near the incision, sometimes like a water balloon under the skin. It may cause pressure, tightness or mild discomfort. Redness, warmth and increasing pain are not typical and suggest infection.

How long does a seroma last?

Small seromas often disappear within a few weeks to a few months as the body reabsorbs the fluid. Larger seromas may need to be drained, sometimes more than once. A seroma lasting many months may need further treatment.

Should a seroma be drained?

Not always. Small, painless seromas can be left to resolve. Drainage is recommended if a seroma is large, painful, stretching the skin, leaking, or affecting healing or further treatment. Drainage should be done by your surgical team.

Is a seroma dangerous?

Usually not. Seromas are a common, mostly harmless complication. The main risk is infection. Contact your surgeon if the area becomes red, hot or more painful, or if you develop a fever.