Mastitis

🔍 When to Suspect

A painful, tender, hot, swollen, wedge-shaped area of erythema on one breast, often with fever (often ≥ 38°C), chills, and flu-like malaise

From the full topic in The Ocean Library: Mastitis

🧭 When to suspect

Mastitis is inflammation of the breast, sitting on a spectrum that runs from a blocked duct and engorgement, through non-infective inflammatory mastitis, to bacterial mastitis and ultimately a breast abscess. The classic presentation is a unilateral, wedge-shaped area of erythema that is tender, firm and hot, frequently accompanied by systemic, flu-like upset – fever (often ≥ 38°C), rigors, myalgia and malaise. On darker skin tones the erythema may be subtle or absent, so weight the firmness, heat and tenderness rather than relying on visible redness.

Most cases are lactational, typically in the first six weeks postpartum and usually driven by milk stasis (poor attachment, missed feeds, oversupply, pressure on the breast). Non-lactational mastitis is less common, periareolar or subareolar, and strongly associated with smoking. The key primary-care skills are threefold: distinguish mastitis from its mimics, recognise that most cases settle with conservative measures so antibiotics are reserved rather than reflexive, and never miss a breast abscess, sepsis, or an inflammatory breast cancer hiding behind a “mastitis” that will not resolve.

Presentation	Distinguishing features
Blocked duct	Focal, tender lump with little or no erythema and no systemic upset; resolves with continued feeding.
Engorgement	Bilateral, generalised firm swelling, classically days 3–5 postpartum or after missed feeds; minimal fever.
Lactational mastitis	Unilateral wedge of erythema, heat and tenderness plus systemic flu-like symptoms; commonest organism Staphylococcus aureus.
Breast abscess	Well-defined, fluctuant tender mass; a complication of mastitis that persists despite antibiotics.
Inflammatory breast cancer	Diffuse erythema and oedema with peau d’orange, often no fever, and does not resolve with antibiotics – must be excluded.

⚠️ Common pitfall Labelling every red, tender breast as “infective mastitis” and giving repeated antibiotic courses. Inflammatory breast cancer classically masquerades as a recurrent or antibiotic-unresponsive mastitis, and is the easy diagnosis to miss in a non-lactating or older woman. Always document complete resolution after treatment: erythema, oedema or a lump that fails to settle is an indication to image and refer, not to re-prescribe.

Source: NICE · Academy of Breastfeeding Medicine

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