Breast abscess

Question 1

What is it?

Answer 1

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)
- smoking is risk factor

Question 2

Causes?

Answer 2

The most common causative bacteria are:

Staphylococcus aureus (the most common)
Streptococcal species
Enterococcal species
Anaerobic bacteria (such as Bacteroides species and anaerobic streptococci)

Question 3

Presentation?

Answer 3

Mastitis with infection in the breast tissue presents with breast changes of:

Nipple changes
Purulent nipple discharge (pus from the nipple)
Localised pain
Tenderness
Warmth
Erythema (redness)
Hardening of the skin or breast tissue
Swelling
The key feature that suggests a breast abscess is a swollen, fluctuant, tender lump within the breast. Fluctuance refers to being able to move fluid around within the lump using pressure during palpation. Where there is infection without an abscess, there can still be hardness of the tissue, forming a lump, but it will not be fluctuant as it is not filled with fluid.

There may be generalised symptoms of infection, such as:

Muscle aches
Fatigue
Fever
Signs of sepsis (e.g., tachycardia, raised respiratory rate and confusion)

Question 4

Management?

Answer 4

The diagnosis of mastitis or a breast abscess can usually be made clinically, with a history and examination.

The NICE clinical knowledge summaries (last updated January 2021) recommend different management for mastitis depending on whether it is lactational or non-lactational.

Lactational mastitis caused by blockage of the ducts is managed conservatively, with continued breastfeeding, expressing milk and breast massage. Heat packs, warm showers and simple analgesia can help symptoms. Antibiotics (flucloxacillin or erythromycin/clarithromycin where there is penicillin allergy) are required where infection is suspected or symptoms do not improve.

Management of non-lactational mastitis involves:

Analgesia
Antibiotics
Treatment for the underlying cause (e.g., eczema or candidal infection)

Antibiotics for non-lactational mastitis need to be broad-spectrum. The NICE clinical knowledge summaries (last updated January 2021) recommend either:

Co-amoxiclav
Erythromycin/clarithromycin (macrolides) plus metronidazole (to cover anaerobes)

Management of a breast abscess requires:

Referral to the on-call surgical team in the hospital for management
Antibiotics
Ultrasound (confirm the diagnosis and exclude other pathology)
Drainage (needle aspiration or surgical incision and drainage)
Microscopy, culture and sensitivities of the drained fluid

Women who are breastfeeding are advised to continue breastfeeding when they have mastitis or breast abscesses. They should regularly express breast milk if feeding is too painful, then resume feeding when possible. This is not harmful to the baby and is important in helping resolve the mastitis or abscess.