• Do not miss septic/toxic patient – if present administer early IV antibiotics/fluid resuscitate and consult obstetrics/general surgery early. Consider Vancomycin 25-30 mg/kg loading dose.
• Examine for any evidence of mass; ruling out breast abscess. With any mass, consider cancer.

• ~2-10% of breastfeeding persons.
• Most common in the first 3 months postpartum during lactation = lactational mastitis.
• Mastitis is a continuum of disease following ductal narrowing and stromal edema. If worsened by hyperlactation, inflammatory mastitis can develop which can progress to acute bacterial mastitis and the development of abscess (Rationale: Milk stasis is not strongly correlated with mastitis.)
• The differential diagnosis of a breast abscess includes galactocele (milk retention cyst), fibroadenoma, and inflammatory breast carcinoma.
• Infection most often happens when bacteria enter the breast through the nipple.
• Most commonly caused by S aureus (MSSA), less frequently S pyogenes(group A or B), E coli, Bacteroides, Corynebacterium, and MRSA.

Risk Factors:

• Poor breast attachment.
• Nipple cracking or inflammation.
• Hyperlactation
• Regular breast pump use
• Exposure to antibiotics
• Tissue trauma from aggressive breast massage
• Previous mastitis
• Use of nipple shields
• Rapid weaning or frequent missed feedings
• Tight clothing that may traumatize or pressurize breast tissue.
• Maternal stress and fatigue.

Protective Factors:

• Direct breastfeeding
• Optimizing infant latch
• Probiotics may be beneficial in reducing the risk of mastitis but evidence low quality.

Presentation:

• Unilateral breast pain, erythema, +/- fever.
• Inflammatory mass.
• May have associated sore/cracked nipples, or plugged milk ducts.
• Systemic symptoms: fever, chills, myalgia, fatigue.

Physical Exam:

• Thorough examination of the breast tissue and axilla.

Investigations:

• Mastitis is a clinical diagnosis – laboratory tests and imaging are generally not needed, unless an abscess is suspected which can be assessed by ultrasound.
• Breast milk culture may be useful to guide antibiotic selection IF severe infection, hospital acquired, or unresponsive to initial empiric antibiotics.
• In patients with suspected abscess, ultrasound may be a useful tool to help characterize mass, obtain sample for gram stain & culture and some symptom relief.

• Encourage ongoing breastfeeding:
  • continue to breastfeed with affected breast – no evidence of risk to infant.
  • If the baby is not exclusively breastfeeding or has been needing ongoing supplementation, continue usual pumping routine, often 8 times in 24 hours. Counsel mothers against pump overuse. If there are signs of hyperlactation, may consider reducing pumping sessions to 6 times in 24 hours.
• Regardless of whether primarily inflammatory or infectious, initiate supportive measures
  • Hand expressing, lymphatic drainage and reverse pressure softening may provide relief.
  • Cold compresses, analgesics including acetaminophen or and NSAIDs and rest.
  • Avoid deep massage of the breast
  • Address maternal mental health
  • Refer to public health to improve infant feeding technique and/or assess pumping assessment

• Since mastitis are often caused by inflammation instead of a true infection, there are evidence supporting a 1-2 days trial of conservative measures (prior to starting antibiotics) may be sufficient to treat the condition
• Addition of antibiotics based on clinical judgement. Empiric antibiotic therapy directed against S aureus
  • Without risk factors for MRSA: outpatient oral cephalexin or cloxacillin (500mg QID; 10-14 days – poorly defined).
  • Non-severe infection with risk for MRSA: oral trimethoprim-sulfamethoxazole (2 tabs BID).
  • Severe infection (sepsis) – empiric inpatient therapy initially with IV Vancomycin.
  • Non-peurperal non-lactating mastitis): can use clavulin po or clindamycin po/IV.
• Drain abscesses – often amenable to needle aspiration. If very large abscess, or there is failure of needle aspiration, then incision and drainage. Gram stain and C/S.

Typically managed as outpatient. Admission should be considered if patient is ill, requiring IV antibiotics, or do not have supportive care at home.

Resources insufficient for management of sepsis.

Closely observe for any evidence of sepsis or clinical deterioration. General surgery consult.

Discharge home with adequate instructions for analgesia and antibiotic treatment if appropriate. Also include identification of early warning signs of mastitis including engorgement, blocked ducts, and nipple soreness.

1. https://myhealth.alberta.ca/Health/aftercareinformation/pages/conditions.aspx?hwid=uh2819

   
   

1. Louis-Jacques, A.F., Berwick, M. and Mitchell, K.B., 2023. Risk factors, symptoms, and treatment of lactational mastitis. JAMa, 329(7), pp.588-589.

    

    

   
   

2. Mitchell, K.B., Johnson, H.M., Rodríguez, J.M., Eglash, A., Scherzinger, C., Widmer, K., Berens, P., Miller, B. and Academy of Breastfeeding Medicine, 2022. Academy of breastfeeding medicine clinical protocol# 36: the mastitis spectrum, revised 2022. Breastfeeding medicine, 17(5), pp.360-376.

    

   
   

3. Morcomb, E.F., Dargel, C.M. and Anderson, S.A., 2024. Mastitis: rapid evidence review. American Family Physician, 110(2), pp.174-182.

   
   

https://www.who.int/publications/i/item/WHO-FCH-CAH-00.13