What is a seroma?

What is a Seroma?

A seroma is a collection of serous fluid (clear, straw-colored fluid containing serum, lymph, and tissue exudate) that accumulates beneath the skin or in a surgical cavity following tissue dissection, trauma, or surgery. 1, 2

Pathophysiology and Formation

• Seromas develop when surgical dissection or tissue undermining creates a dead space where fluid can accumulate, consisting of serum, lymph, and exfoliated tissue fluid. 1, 2
• The true etiology remains incompletely understood, but a multifactorial causation is accepted, involving surgical technique, extent of tissue dissection, and patient-specific factors. 2
• Fluid accumulation occurs because the body continues to produce serous fluid in response to tissue injury while the dead space prevents natural reabsorption. 2

Common Clinical Contexts

• Breast surgery: Seromas are the most frequent complication following mastectomy and axillary surgery, occurring in a significant proportion of patients. 2, 3
• Implant-based reconstruction: Fluid collections around breast implants typically develop within the first week after surgery, though small amounts of periprosthetic fluid may be normal. 4, 5
• Abdominal wall surgery: Seromas commonly occur after procedures involving extensive tissue dissection, such as hernia repairs and panniculectomy. 6
• General surgical drains: Drainage devices are specifically used to remove serum, lymph, and other fluids that accumulate in wound beds to prevent seroma formation. 4

Clinical Presentation

• Patients typically present with swelling, asymmetry, or a sensation of fullness at the surgical site. 4, 5
• Most seromas develop within the first week following surgery, though "late seromas" can occur beyond this expected timeframe (documented as late as 21 days post-operatively). 5, 1
• Physical examination reveals a fluid collection that may be fluctuant on palpation. 2

Diagnostic Considerations

• Imaging confirmation: Ultrasound is the preferred initial imaging modality to confirm the presence of a fluid collection and differentiate it from other complications. 4
• Distinguishing from other complications: Seromas must be differentiated from hematomas (blood collections), abscesses (infected fluid), and other pathology through imaging characteristics and clinical context. 4, 7
• Fluid analysis: When aspirated, seroma fluid should be sent for cell count, culture, and analysis to differentiate from infected collections or bleeding. 4
• In breast implant cases, seromas can be mistaken for implant rupture or capsular contracture, requiring imaging for accurate diagnosis. 4, 5

Clinical Significance and Complications

• Infection risk: The primary concern with seromas is their potential to become infected, particularly around prosthetic devices where the fluid collection is relatively isolated from the host immune system. 4, 8
• Treatment delays: Prolonged drainage or persistent seromas can delay adjuvant therapies such as chemotherapy or radiation. 2, 3
• Diagnostic interference: Large seromas may obscure residual calcifications on post-operative mammograms or lead to unnecessary biopsies. 5
• Device-related concerns: In implant-based reconstruction, seromas between acellular dermal matrices and implants carry increased infection risk (relative risk 2.47). 4, 9

Important Distinctions

• Seroma versus other fluid collections: Seromas should not be confused with subdural fluid collections, CSF leaks, or other anatomically distinct fluid accumulations, as these require different management approaches. 7
• Normal versus pathologic fluid: Small incidental volumes of periprosthetic fluid around implants may be normal and common; larger volumes or symptomatic collections warrant intervention. 4
• Infected versus sterile: Sterile seromas can be managed conservatively, while infected collections require more aggressive treatment including antibiotics and possible surgical intervention. 4, 2