Lactational Breast Abscess

Lactational breast abscess is a collection of pus in the breast of a breastfeeding woman, usually as a complication of mastitis that was not treated early or fully. Staphylococcus aureus (including methicillin-resistant strains) causes most cases, with streptococci and anaerobes less often. It occurs in a minority of women with mastitis, and matters because it causes severe pain and sepsis, and stopping breastfeeding is rarely needed.

• Risk factors: untreated or delayed treatment of mastitis, nipple trauma, milk stasis, first baby, age above 30 years, smoking, diabetes, HIV, obesity.
• Usually appears 2 to 4 weeks after birth, and again at weaning.
• Needle aspiration is often enough for small and medium abscesses.

Women have a painful red hot swelling of the breast with fever, chills and malaise, usually after several days of mastitis that has not settled. A fluctuant tender mass is present, with shiny skin and nipple discharge in some.

• Fluctuant swelling, local warmth, overlying skin redness and tender axillary nodes.
• Fever above 38.5 degrees Celsius that persists despite 48 hours of antibiotics.
• Differential diagnosis: mastitis without abscess, blocked duct, galactocele, infected cyst, fibroadenoma, inflammatory breast cancer, tuberculous abscess, periductal mastitis, granulomatous mastitis.
• Complications: sepsis, recurrence, milk fistula, breast tissue loss, scarring, chronic pain, early weaning.

The approach is clinical, confirmed by ultrasound with aspiration for culture.

• Palpation for fluctuance; temperature, pulse and blood pressure; examination of the axilla.
• Breast ultrasound to show a fluid collection and its size, depth and loculations.
• Pus culture and sensitivity (including methicillin-resistant Staphylococcus aureus); full blood count, C-reactive protein; blood culture if febrile or systemically unwell; glucose.
• Biopsy of the wall if a mass persists after drainage or appears atypical.

The principle is drainage of the pus with antibiotics, while continuing breastfeeding or milk expression.

• Supportive: continue breastfeeding or express from the affected breast as pain allows; support the breast with a bra; warm compress before feeds and cold compress after; paracetamol for pain; fluids; rest; admission for sepsis or large abscess.
• Pharmacological: lignocaine 1 percent infiltration, 5 to 20 mL (maximum 3 mg/kg, not above 200 mg), for aspiration or drainage; flucloxacillin 500 mg oral 6-hourly for 10 to 14 days (1 g IV 6-hourly if systemically unwell, then oral when afebrile for 24 hours); cefalexin 500 mg oral 6-hourly for 10 to 14 days as an alternative; penicillin allergy or methicillin-resistant Staphylococcus aureus: clindamycin 300 to 450 mg oral every 6 to 8 hours for 10 to 14 days, or vancomycin 15 mg/kg IV 12-hourly for severe infection; paracetamol 1 g oral 6-hourly (maximum 4 g in 24 hours); ibuprofen 400 mg oral 8-hourly with food for 3 to 5 days.
• Procedures: ultrasound guided needle aspiration under local anaesthesia with a 16 to 18 gauge needle, repeated every 1 to 3 days until no more pus is obtained; incision and drainage with a small incision placed away from the nipple and a drain or wick for abscess larger than 5 cm, thin or necrotic skin, multiloculated abscess or failed aspiration.
• Special groups: women with diabetes need insulin to keep glucose below 10 mmol/L and a full 14 day antibiotic course; methicillin-resistant Staphylococcus aureus is treated with clindamycin or vancomycin at the doses given, and the infant is checked for skin infection; breastfeeding from the affected side continues if the wound is away from the nipple and the infant tolerates the milk, and is paused if pus enters the milk or the infant refuses.
• Red flags: persistent fever beyond 48 hours of antibiotics, spreading redness, fluctuance after aspiration, systolic blood pressure below 90 mmHg, necrotic skin, a mass persisting beyond 2 weeks of treatment, bloody discharge.
• Follow-up: review at 24 to 48 hours with ultrasound; repeat aspiration as needed; wound review every 2 days; breast examination and ultrasound at 6 weeks and 6 weeks after weaning; biopsy of any persistent mass.