Breast abscess

• A breast abscess is a collection of pus within an area of the breast, usually caused by a bacterial infection. This may be a:

  • Lactational abscess (associated with breastfeeding) 
  • Non-lactational abscess (unrelated to breastfeeding)
• Mastitis refers to inflammation of breast tissue. Often this is related to breastfeeding (lactational mastitis), although it can be caused by infection. Bacteria can enter at the nipple and back-track into the ducts, causing infection and inflammation. Mastitis caused by infection may precede the development of an abscess.
• Mastitis and abscess:

  • Mastitis - Painful inflammatory condition of the breast
  • Abscess - localised collection of pus
  • 30% of lactating women develop mastitis, most within 2-3 weeks postpartum
  • Non-lactational mastitis occurs in 5-9% of women, most common in women of reproductive age
• Anatomy:

  • Breast contains breast lobules, each draining to a milk duct which empties to the surface of the nipple
  • Injury to the nipple during breastfeeding provides an entry point for the bacteria to enter
  • Inverted nipples predispose to breast infection due to obstruction of the ducts
• Mastitis can be divided into 3 categories:

  • Lactational - breastfeeding, staph aureus
  • Non lactational - infection is usually mixed - staph aureus, enterococci, anaerobic bacteria
  • Granulomatous - rare breast infection which occurs in women with diabetes, autoimmune disease and sarcoidosis
• A breast abscess is a complication of mastitis
• Lactational mastitis happens due to milk stasis due to reduced breastfeeding. This can happen due to:

  • Changes in feeding regime
  • Introduction of bottle feeding
  • Poor attachment of the infant to the breast
  • Maternal stress and fatigue
• Non-lactational mastitis is commonly seen in smokers due to damage to ducts secondary to hypoxia.
• Other risk factors for mastitis include:

  • Inverted nipples
  • Nipple piercings
  • Skin conditions such as eczema
  • Diabetes
  • Immunosuppression
• Typical symptoms of mastitis/breast abscess include:

  • Erythema of the breast
  • Swelling of the breast
  • Painful breast
  • Fever and general malaise
• Typical clinical findings of mastitis/breast abscesses on breast examination include:

  • Warm/hot skin
  • Tender, firm breast
  • The presence of fluctuation suggests abscess formation
• Investigations:

  • Clinical diagnosis and does not require investigations
  • If breast abscess is suspected - urgent USS
• Mastitis management:

  • Analgesia
  • Advise to continue breastfeeding
  • Addressing any underlying/predisposing risk factors
  • Lactating women: flucloxacillin 10-14 days
  • Non-lactating women: co-amoxiclav
  • Consider hospital admission if signs of sepsis or patient is immunocompromised
• Breast abscess management:

  • Referral to on-call surgical team
  • Antibiotics
  • Ultrasound - confirm diagnosis and exclude other pathology
  • Drainage - needle aspiration or surgical incision and drainage (choice if septic)
  • MC+S of drained fluid
• If the abscess does not resolve after antibiotics and ultrasound aspirations, an ultrasound-guided core biopsy should be performed to exclude malignancy or granulomatous mastitis.