Mastitis

Definition

Mastitis is inflammation of the breast tissue, commonly due to infection, leading to pain, swelling, redness, and systemic symptoms, most frequently occurring in lactating women.

Epidemiology

• Affects 2–10% of breastfeeding women, typically within the first 6 weeks postpartum.
• More common in primiparous women and those with poor breastfeeding technique.
• Non-lactational mastitis is less common and may be associated with chronic conditions or smoking.
• Staphylococcus aureus is the most common causative organism.

Etiology

• Infectious: bacterial infection, primarily Staphylococcus aureus; less commonly Streptococcus species.
• Mechanical: nipple trauma, cracked nipples, or milk stasis leading to infection.
• Risk factors: poor latch during breastfeeding, infrequent feeding, breast engorgement, immunosuppression.
• Non-infectious: duct ectasia, inflammatory breast disorders, trauma, autoimmune conditions.

Pathophysiology

• Milk stasis increases intraductal pressure, causing tissue inflammation.
• Bacterial entry via nipple cracks leads to local infection and immune response.
• Inflammation causes pain, erythema, and edema.
• Systemic inflammatory response may lead to fever, malaise, and leukocytosis.
• Chronic or recurrent inflammation may cause abscess formation or ductal changes.