Postoperative Seroma

A postoperative seroma is a collection of serous fluid in a surgical dead space. It is a common complication that is usually self-limiting, although it can delay healing and become infected.

Epidemiology. It follows about 5% to 30% of mastectomy with axillary clearance, 10% to 40% of abdominal wall hernia repair with mesh (often subclinical on imaging), and 15% to 30% of abdominoplasty, lipectomy and large flap operations. Lymphadenectomy of the groin and axilla and large dissection planes carry the greatest risk.

Risk factors. Obesity, extensive dissection, lymph node clearance, large dead space, shearing between flap and bed, early drain removal, anticoagulation, previous radiotherapy, diabetes and electrocautery dissection.

Pathophysiology.

Transected lymphatics and capillaries leak plasma like fluid with high protein content. Fluid collects where tissue planes cannot appose.

Persistent seromas form a fibrous capsule that may calcify or harbour bacteria.

A fluctuant, non-tender swelling that appears 3 to 10 days after surgery or after drain removal, with fluid sloshing, mild discomfort and sometimes wound leakage of straw coloured fluid.

Red flags.

• Fever, erythema, warmth, purulence or rising pain (infection).
• Tense swelling with skin threatened.
• Rapid enlargement or blood stained fluid (haematoma).
• Mesh prosthesis exposure.

Clinical examination is usually enough. Ultrasound shows an anechoic collection and directs aspiration. Send fluid for culture only if infection is suspected. Take cytology if the cause is unclear, particularly after cancer surgery. CT or MRI for deep or recurrent collections.

Differential diagnosis.

• Haematoma.
• Abscess.
• Lymphocele.
• Hernia recurrence.
• Tumour recurrence.
• Fat necrosis.
• Cellulitis.

Asymptomatic small seroma. Observe. Many reabsorb within weeks.

Symptomatic or large seroma. Aspirate under aseptic technique using ultrasound direction, using a fine needle through intact skin away from the incision. Repeat as needed, though repeated aspiration increases infection risk, so more than 2 to 3 attempts favour a drain or sclerotherapy. Apply compression.

Persistent seroma. Insert a closed suction drain and remove when output is under 30 mL in 24 hours. Options include sclerotherapy with doxycycline or talc and surgical excision of the capsule.

Infected seroma. Drain, culture, and treat with antibiotics chosen for the likely source organisms.

• Flucloxacillin: 500 mg to 1 g orally every 6 hours for 5 to 7 days; maximum 4 g daily orally; monitor liver enzymes (cholestatic hepatitis); extend interval if creatinine clearance is under 10 mL/min; avoid in penicillin allergy.
• Doxycycline (penicillin allergy): 100 mg orally twice daily for 5 to 7 days; maximum 200 mg daily; monitor for oesophagitis and photosensitivity; avoid in pregnancy and under 12 years.
• Add cover for meticillin resistant Staphylococcus aureus where prevalent, such as doxycycline or linezolid 600 mg orally every 12 hours.

Prevention. Obliterate dead space with quilting sutures, use compression garments, use drains until output is under 30 mL in 24 hours, limit shoulder movement for several days after axillary surgery, and avoid excess diathermy.

Monitoring. Size and symptoms at each review, drain output, temperature and wound appearance.

Referral and escalation. Surgical review for recurrent, infected or mesh related seroma. Plastic surgery advice for flap complications.