Mastitis

Aka: Mastitis, Lactation Mastitis, Breast Abscess, Breast Abscess During Lactation

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II. Epidemiology

  1. Incidence: 9-33% of lactating women (estimated 10% in U.S.)
  2. Most common in first few weeks and nearly all cases within first 3 months

III. Pathophysiology

  1. Generally occurs in Lactation several weeks postpartum
  2. Bacteria enter through a cracked nipple

IV. Risk Factors: Lactation Mastitis

  1. Breast Milk production overstimulation (hyperlactation, excessive Breast Pumping)
  2. Excessive Breast Massage
  3. Recent Antibiotics (may modify skin flora)
  4. Nipple shields
  5. Poor infant latch (e.g. Cleft Lip, ankyloglossia) increased risk of nipple Trauma
  6. Tight bra or other clothing
  7. Mastitis History
  8. Primiparous women
  9. Poor maternal nutrition
  10. Debunked factors that are no longer thought related to Mastitis pathogenesis
    1. Milk stasis
    2. Yeast infection
      1. Betts (2021) Breastfeed Med 16(4): 318-24 [PubMed]

V. Risk Factors: Nonlactation Mastitis (uncommon)

  1. Hispanic ethnicity
  2. Immunosuppression
  3. Breast Cancer
    1. Chang (2019) Sci Rep 9(1): 15587 [PubMed]

VI. Causes

  1. Staphylococcus (typical skin flora)
    1. Staphylococcus aureus
    2. Staphylococcus epidermidis
    3. Staphylococcus lugdunensis
    4. Staphylococcus hominis
  2. Streptococcus (typical skin flora)
    1. Streptococcus mitis
    2. StreptococcusSalivarius
    3. Streptococcus Pyogenes
    4. Streptococcus agalactiae
  3. Other less common Bacterial causes
    1. Escherichia coli
    2. HaemophilusInfluenzae

VII. Symptoms

  1. Fatigue
  2. Malaise
  3. Myalgias
  4. Headache

VIII. Signs

  1. Systemic symptoms
    1. Fever (>100.9 F or 38.3 C)
      1. May also reflect inflammatory changes and not significant Bacterial Infection
    2. Malaise, Fatigue and Influenza-like symptoms
    3. Headache
  2. Breast inflammation
    1. Unilateral involvement (contrast with bilateral involvement in Breast engorgement)
    2. Warmth
    3. Focal tenderness
    4. Erythema
    5. Indurated skin (typically segmental)
  3. Observe for signs of Breast Abscess
    1. Requires needle aspiration

IX. Labs

  1. Laboratory testing is not needed in typical cases
    1. CRP and CBC offer little beyond clinical diagnosis
  2. Milk Culture
    1. Indications (not routine)
      1. Recurrent or severe Mastitis
      2. Refractory despite optimal Antibiotics for at least 48 hours
      3. Hospital acquired infection (e.g. infant in NICU)
      4. Immunocompromised patients
      5. MRSA Risk (or other Antibiotic Resistance)
    2. Technique
      1. Cleanse nipple
      2. Hand express small quantity of Breast Milk and discard
      3. Hand express a sample into a sterile container

X. Imaging

  1. Breast Ultrasound
    1. Consider for Breast Abscess evaluation if not improving at 48 hours of treatment

XI. Differential Diagnosis

  1. Early Postpartum Breast engorgement
    1. Bilateral Breast Pain, typically starting within 3 to 5 days of delivery
  2. Plugged milk ducts
    1. Presents with congested Breast tissue and often resolves with observation, and NSAIDS as needed
  3. Subacute Mastitis
    1. Needle sharp, burning Breast Pain with local induration and milk blebs without systemic symptoms
    2. Resolves with observation, continued physiologic direct feeding from Breast and NSAIDS as needed
  4. Inflammatory Mastitis
    1. Noninfectious, but nearly identical to Mastitis (fever, unilateral, segmental Breast inflammation)
    2. Typically improves with NSAIDs and topical ice
  5. Breast Abscess
    1. Well-defined fluid collection on exam as a discrete fluctuant swelling or by Ultrasound
    2. Treated with needle aspiration or surgical drain placement by Breast surgeon (avoid packing wounds)
  6. Phlegmon
    1. Firm, mass-like swelling without a discrete fluctuant, drainable abscess by exam or Ultrasound
    2. Ultrasound to differentiate from abscess, and avoid drainage unless organizes into a discrete abscess
  7. Galactocele
    1. Milk duct narrowing with a secondary milk-containing cyst often decreasing in size with Breast Feeding
    2. No signs or symptoms of infection to suggest Mastitis, abscess or phlegmon
  8. Inflammatory Breast Cancer
    1. Consider in non-lactating Mastitis

XII. Management: General Measures

  1. See prevention for additional strategies
  2. Ensure adequate hydration
  3. Alternate feeding positions
  4. Analgesics
    1. Acetaminophen
    2. NSAIDS (e.g. Ibuprofen 600 mg every 6 hours)
    3. Soy lecithin or sunflower 5-10 g/day (or divided 1200 mg 3-4 times daily)
      1. May decrease duct inflammation and improve milk emulsification
  5. Apply cool compresses
    1. Warm packs are frequently recommended, but may worsen symptoms
  6. Gentle local massage
    1. Avoid aggressive or deep Breast Massage
  7. Treat Breast engorgement (reduces pain, and reduces nipple and areola swelling)
    1. Lymphatic drainage maneuvers
      1. https://www.youtube.com/watch?v=24MAkakR5k8
    2. Reverse pressure softening
      1. https://www.youtube.com/watch?v=3ULnIUeHAIM
    3. Block Feeding
      1. Feed from only the unaffected Breast for 24-48 hours
      2. Allows the engorged Breast time to decompress and for form less milk
  8. Continue with frequent Breastfeeding (except if Breast Abscess present)
    1. Avoid over-feeding or over-pumping (may increase milk production and worsen symptoms)
    2. Risk of Breast Abscess if Breast engorgement occurs
    3. Ensure proper technique (see prevention below)
    4. Safe for infant to continue to feed despite infection with following exceptions
      1. Mother HIV positive
      2. Significant edema at areola interferes with milk expression
        1. Breast rest for 24 to 48 hours may allow swelling to decrease and for milk flow to resume
      3. Breast Abscess
        1. Discard Breast Milk for the first 24 hours on Antibiotics
        2. Resume Breast Feeding after the first 24 hours on Antibiotics
  9. Avoid treating nipple Bacterial or fungal colonization
    1. Previously thought to lead to ascending infection, but no longer thought to play a significant role
    2. Staphylococcus aureus colonized nipples
      1. Previously recommended for treatment (e.g. Dicloxacillin), but no longer recommended
      2. Livingstone (1999) J Hum Lact 15:241-6 [PubMed]
    3. Antifungals (Monilial Infection)
      1. Fungal infection is no longer thought to significantly contribute to Mastitis
      2. Thush may still be treated when present in infants (Oral Nystatin or Fluconazole)
      3. Maternal fungal colonization was previously treated (no longer recommended)
        1. Topical Antifungals (Nystatin, Ketoconazole) at the nipple and areola
        2. Oral agents: Fluconazole 400 mg on day #1, then 200 mg orally daily for 10 days
        3. Chetwynd (2002) J Hum Lact 18:168-71 [PubMed]
  10. Avoid unhelpful or harmful measures that were previously recommended
    1. Deep or aggressive Breast Massage or vibration
    2. Frequent and complete Breast emptying (results in hyperlactation)
    3. Applying frozen cabbage leaves to Breast (no benefit over other cold application)
    4. Dangle or gravity feeding (mother leaning over infant to feed)
    5. Applied heat (use cold instead)
    6. Breast Milk plug release (using a Manual Breast Pump or Haakaa)
    7. Unroofing milk blebs (milk Blisters)
      1. Blocked milk ducts were recommended for unblocking with a moist cloth (no longer recommended)
      2. Blocked ducts will appear with a bleb overlying a tender, red area adjacent to nipple
    8. Topical agents (epsom salts, Castor Oil, saline soaks)
      1. Unlikely to benefit and may cause Breast tissue damage
  11. Follow-up
    1. If not improving in 48 hours on Antibiotics and other conservative measures, examine Breast for abscess

XIII. Management: Antibiotics

  1. Course: 10 to 14 days
  2. Coverage: Staphylococcus and Streptococcus (see causes above)
  3. May observe localized Breast redness, tenderness without systemic symptoms or abscess for 24 hours
    1. For first 24 hours may use general measures above and hold Antibiotics
    2. Start Antibiotics by 24 hours if not improving, systemic symptoms, other risks
    3. Antibiotics are typically started without delay in non-lactating Mastitis
  4. Antibiotics: First-Line (including Nursing Mothers)
    1. Amoxacillin 500 mg orally four times daily
    2. Cefadroxil (Duricef) 500 mg orally twice daily
    3. Cephalexin (Keflex) 500 mg orally four times daily
    4. Dicloxacillin 500 mg orally four times daily
  5. Second-line agents
    1. Clindamycin 300 mg orally four times daily
    2. Trimethoprim-sulfamethoxazole (Septra) 160mg/800 mg orally twice daily (for MRSA)
      1. Avoid in G6PD Deficiency and in mothers with infants <2 months of age
      2. May be used in Lactation after first 2 months of life (risk of Kernicterus in newborns)
  6. Adjuncts
    1. Consider Corticosteroids (e.g. Dexamethasone 10 mg orally once) In non-lactating Mastitis (Granulomatous Mastitis)
    2. Martinez-Ramos (2019) Breast J 25(6): 1245-50 [PubMed]

XIV. Management: Breast Abscess

  1. Obtain Bacterial culture
  2. Needle aspiration under Ultrasound guidance (preferred, 60% effective)
    1. Attempt to irrigate the abscess via the same needle used for aspiration
    2. May repeat up to 3 times if fails to resolve (then incise in drain if still refractory)
  3. Incision and Drainage
    1. Breast surgeon Consultation is recommended
    2. Indicated in refractory cases (after 3 attempted needle aspirations)
    3. Also first-line measure in very superficial lesions, with skin thinning over the abscess
    4. Do NOT pack wounds (risk of increased inflammation and delayed healing)
    5. Surgical drain placement is recommended (typically by Breast surgeon)
  4. Complications
    1. Milk fistula (complicates<2% of abscess drainages)
  5. References
    1. Sacchetti in Herbert (2016) EM:Rap 16(5): 1

XV. Prevention

  1. Optimal Breast Feeding Technique with good latch-on by infant
  2. Maintain healthy lifestyle
    1. Adequate sleep and stress reduction
    2. Adequate and Healthy Nutrition (e.g. Mediterranean Diet)
  3. Avoid excessive Breast Pumping
    1. Physiologic feeding directly from Breast is optimal (reduces hyperlactation)
    2. Try to limit Breast Pumping to times when infant is separated from mother
    3. Pump only the amount of milk the baby will consume (avoid fully emptying the Breast)
      1. Breast Milk production increases to match usage (supply and demand)
  4. Sore nipples suggest problems
    1. Correct latch-on problems
    2. Address dry nipples with lanolin
    3. Avoid plastic-backed Breast pads
    4. Evaluate infant for anatomic problems (e.g. short frenulum, Cleft Palate)
  5. Technique
    1. Use proper Breast Pump flange size to avoid nipple Trauma
    2. Avoid nipple shields (or limit to shortest amount of time)
      1. No proven benefit and reduce milk extraction and may predispose to Mastitis
  6. Address predisposing factors early

XVI. References

  1. Barbosa-Cesnik (2003) JAMA 289:1609-12 [PubMed]
  2. Morcomb (2024) Am Fam Physician 110(2): 174-82 [PubMed]
  3. Spencer (2008) Am Fam Physician 78(6): 727-32 [PubMed]
  4. Westerfield (2018) Am Fam Physician 98(6): 368-73 [PubMed]

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