Mastitis and Breast Abscess
NICE CKS Mastitis and breast abscess. Last revised: Mar 2025.
Background Information
Definition
Mastitis: a painful inflammatory condition of the breast
Breast abscess: a localised collection of pus within the breast
Aetiology
The most common cause is lactational mastitis and abscesses (which occur in breastfeeding women)
- Pathophysiology: milk stasis due to incomplete emptying / blocked duct / nipple trauma → inflammation → secondary bacterial infection
- Most common organism: Staphylococcus aureus
Risk factors:
- Poor infant attachment to the breast
- Reduced number or duration of feeds (e.g. partial bottle feeding, painful breasts, infant having a preferred breast for feeding)
- Age (21-35 y/o has the highest risk)
- Smoking
- Nipple damage / trauma to the breast
- Underlying breast abnormalities
- Immunosuppression
Non-lactating mastitis and abscesses also exist, but are less common
- Periductal mastitis is an example, it is associated with smoking
Diagnosis
Clinical Features
Mastitis
Key clinical features
- Unilateral red, swollen, tender area of the breast (typically in a wedge-shaped distribution)
- Painful breast
- Systemic upset (e.g. fever, malaise)
Breast Abscess
- Possibly a history of recent mastitis (not necessary)
- Painful, red, fluctuant mass on the breast (fluctuance is the hallmark sign of an abscess)
- Systemic upset (e.g. fever, malaise)
Investigation and Diagnosis
Mastitis
Breast milk culture is NOT routinely required, unless:
- Hospital-acquired infection i likely
- Recurrent / severe mastitis
- Atypical presentation
Breast Abscess
Suspected breast abscess requires urgent referral to secondary care for:
- Ultrasound to confirm the diagnosis
Management
Mastitis
Lactational mastitis management:
| Symptomatic management (all patients) |
|
| Advice on effective milk removal from the breast (all patients) |
|
| Do NOT routinely prescribe an antibiotic | Indications for antibiotics:
Choice of antibiotics:
|
For non-lactational mastitis, all patients should be offered an oral antibiotic
- 1st line: co-amoxiclav
- 2nd line: macrolide (erythromycin / clarithromycin) + metronidazole
Breast Abscess
Urgent referral to secondary care
Secondary care management for all patients:
- Drainage of the abscess (ultrasound-guided needle aspiration / surgical drainage) – most important management
- Antibiotic therapy (guided by culture)
- Advice on effective milk removal from the breast
- 1st line: continue breastfeeding (both affected and unaffected breasts)
- If breastfeeding is too painful / the infant refuses to breastfeed from the affected side → hand express breast milk
Note that for breast abscess, antibiotics alone without removal of pus are unlikely to be curative.