Mastitis

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Clinically Relevant Anatomy

Mastitis is classified as the inflammation of the breast tissue and is often categorised as non-lactational mastitis and lactational mastitis.

Non-lactational mastitis includes idiopathic granulomatous mastitis (IGM) and periductal mastitis. IGM is a benign inflammatory condition, primarily affecting women within 5 years of giving birth. This is a rare type of mastitis, often mimicking breast cancer. Alternatively, periductal mastitis affects the sub-areolar ducts, primarily in women of reproductive age.

Lactational mastitis, also known as, puerperal mastitis is the most common form of mastitis. This typically occurs due to prolonged engorgement of the milk ducts which can progress to an bacterial infection, creating an abscess. While this form of mastitis can occur at anytime during lactation, it is more common in the first 6 weeks of breastfeeding and usually decreases after 3 months.

Epidemiology

Lactational mastitis is estimated to occur up to 20% of breastfeeding women. Meta-analysis from three studies reported 11.1 episodes per 1000 breastfeeding weeks from birth to 25 weeks post-partum. The risk of recurrences of mastitis is higher than in patients with no prior history.

Pathophysiology

Lactational mastitis occurs as a result of poor drainage of milk supply which can progress to infection if left untreated. Inadequate drainage is often a result of but not limited to; over-supply of milk, infrequent feeding, illness of mother or child, rapid weaning and clogged ducts. Bacteria from the mothers skin or infants mouth enter the stagnated milk via cracked nipples and grows leading to an infection. Causative organisms that colonise the mothers skin that result in a breast infection are Staphylococcus aureus, methicillin-resistant S aureus (MRSA), escherichia coli, streptococcus pyogenes, coagulase-negative staphylococci and bacteroides species.

While the etiology of periductal mastitis remains unclear, smoking is thought to be associated with the development of the condition due to the direct damage of the ducts, resulting in inflammation. Diabetes and obesity are also considered as risk factors.

The cause of IGM is also unclear, however, trauma, lactation, autoimmune diseases , hyperprolactinemia and use of oral contraceptive pill have been highlighted as a possible cause.

Clinical symptoms

• Mastalgia or tender nipples
• widespread swelling of the affected breast or both breasts
• Flu like symptoms: body aches, sore throat, fever (oral temperature more than 38° C or 100.4 F)
• Back pain/headaches
• Red streaks on breasts
• Painful, hot lump on breast

Risk Factors

• Hyperlactation
• Cracked/sore nipples
• Infant attachment
• missed feeds/changed routine
• rapid weaning
• illness of mother or baby
• maternal malnutrition
• maternal stress or excessive fatigue
• wearing tightfitting bra restricting milk flow
• chronic medical conditions- diabetes, AIDs, chronic illness, impaired immune system
  

Diagnostic Procedures

The diagnosis of mastitis is usually a clinical diagnosis, whereby laboratory tests and imaging are not required unless a breast abscess is suspected.

Outcome Measures

Breast Inflammatory Symptom Severity Index (BISSI) is a Patient Reported Outcome Measure (PROM) to aid the diagnosis, treatment and clinical monitoring of Inflammatory Conditions of the Lactating Breast (ICLB). ICLB includes non-physiological engorgement, breast abscess, mastitis, and blocked ducts. BISSI provide clinicians and mothers with a simple, quick, immediate, and prognostic measure of pain; hardness/tightness; wellness/sickness; redness; temperature and size of affected area and impact on activities of daily living. It is administered at the time of consultation and uses a Numerical Rating Scale (NRS) to measure pain, systemic symptoms, and functional impact; and a 5-point scale to measure breast hardness/tightness (swelling), breast temperature, redness, and size of the affected area

Management / Interventions

add text here relating to management approaches to the condition

Differential Diagnosis

Engorgement

Engorgement occurs due to interstitial oedema with onset of lactation or accumulation of excess breastmilk. Onset of engorgement occurs 3-5 days post-partum after a vaginal delivery and one to two days after a cesarean. The alveolar ducts distend due to the secretion of mature milk which results in lymphatic and vascular compression

Clogged/plugged duct

Clogged duct is an obstruction of milk flow in a localised area of the breast, pressure increases behind the duct and the mammary tissue gets irritated. As a result a tender lump is often felt. A plugged duct usually occurs gradually either in the ductal system or nipple region, affecting one breast.

Breast abscess

A breast abscess is a area of infection in the breast with a collection of pus. Usual presentation of a breast abscess include; skin discolouration, swelling.

	Mastitis	Engorgement	Clogged ducts
Lump/swelling	Widespread swelling of the breast, usually only affects one breast	Widespread swelling of both breast	Localised, well defined lump, may have a region of engorgement around the plug
Pain/tenderness location	Pain/tenderness encapsulates the whole breast	Pain/tenderness encapsulates the whole breast	localised, tender on palpation. Discomfort with nursing, however, reduced pain post feeding
Type of pain	Burning pain	Throbbing/achy pain	Deep ache, however, can be sharp shooting
Flu like symptoms	body aches, fever	Can have low grade fever	Afebrile, reduced milk supply

Resources

Introduction referenceshttps://www.ncbi.nlm.nih.gov/books/NBK557782/#:~:text=Mastitis%20is%20inflammation%20of%20the,idiopathic%20granulomatous%20mastitis%20(IGM).

Epidemiology

https://medilib.ir/uptodate/show/798

type of pain

https://www.chop.edu/pages/breast-engorgement#:~:text=Breast%20engorgement%20is%20swelling%2C%20tightness,with%20throbbing%20and%20aching%20pain.