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    Lactational Mastitis – Diagnosis and Treatment

    Infections, Obstetrics and Gynecology

    Last Updated Dec 27, 2022
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    By Andrew MacPherson, Mattias Berg, Jack Scobie, Raisa Shabbir

    First 5 Minutes

    • 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. The inflammation is caused by milk stasis and it may progress to infection and abscess formation.
    • The differential diagnosis of a breast abscess includes galactocoele (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 coliBacteroidesCorynebacterium, and MRSA.

    Risk Factors

    • Poor breast attachment.
    • Nipple cracking or inflammation.
    • Inadequate breast drainage – infrequent or insufficient emptying (incl. rapid weaning.)
    • Tight clothing that may traumatize or pressurize breast tissue.
    • Maternal stress and fatigue.

    Protective Factors

    • Frequent breastfeeding.
    • Alternating between breasts for feeding.
    • Breast compression or breast massage prior to latching.
    • Probiotics may be beneficial in reducing the risk of mastitis but evidence low quality.

    Diagnostic Process


    • 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.


    • 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.

    Recommended Treatment

    • Regardless of whether primarily inflammatory or infectious, initiate supportive measures
      • warm compresses, analgesics including acetaminophen or NSAIDs and rest.
    • Encourage complete emptying of the breast every 2 hours:
      • continue to breastfeed with affected breast – no evidence of risk to infant.
      • express/pump milk between feeds.
      • massage breast to help clear blockage (proximal and towards nipple.)
    • 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.

    Criteria For Hospital Admission

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

    Criteria For Transfer To Another Facility

    Resources insufficient for management of sepsis.

    Criteria For Close Observation And/or Consult

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

    Criteria For Safe Discharge Home

    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.

    Quality Of Evidence?


    Recommendations for Symptomatic Treatment.

    Recommendations are based on the Mastitis Causes and Management WHO Statement, an international review.


    Antibiotic Therapy for Mastitis.

    Cochrane review from 2013 found that there is little evidence from available RCTs to assess the effect of antibiotics for mastitis given the high degree of variation between studies.


    Probiotic Therapy for Mastitis.

    Cochrane review from 2020 found that probiotics may reduce the risk of mastitis compared to placebo, but the certainty of evidence is low and full results are unavailable from the largest trial due to a contractual agreement.


    Related Information


    Reference List

    1. Dixon JM. Lactational Mastitis [Internet]. UpToDate. 2022 [cited 2022Nov28]. Available from: https://www.uptodate.com/contents/lactational-mastitis?search=mastitis&source=search_result&selectedTitle=1~61&usage_type=default&display_rank=1

    2. HealthLink BC. Mastitis While Breastfeeding [Internet]. Mastitis While Breastfeeding | HealthLink BC. 2022 [cited 2022Nov28]. Available from: https://www.healthlinkbc.ca/pregnancy-parenting/parenting-babies-0-12-months/breastfeeding/mastitis-while-breastfeeding

    3. Jahanfar S, Ng CJ, Teng CL.  Antibiotics for mastitis in breastfeeding women (review).  Cochrane Database Syst Rev. 2013; 2: Art. No.: CD005458. DOI: 10.1002/14651858.CD005458.pub3.

    4. Kvist LJ, Larsson B, Hall-Lord M, Steen A, Schalén C. The role of bacteria in lactational mastitis and some considerations of the use of antibiotic treatment. International Breastfeeding Journal. 2008;3(1):6.

    5. Mitchell KB, Johnson HM, Rodríguez JM. Academy of Breastfeeding Medicine Clinical Protocol #36: The mastitis spectrum, revised 2022. Breastfeeding Medicine. 2022;17(5):360–76.

    6. Toronto Public Health. Protocol #7 Mastitis [Internet]. Breastfeeding Protocols for Health Care Providers . Toronto Public Health ; 2019 [cited 2022Nov28]. Available from: https://www.toronto.ca/wp-content/uploads/2017/11/9619-tph-breastfeeding-protocol-7-mastitis-2013.pdf

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