What is the initial workup and treatment for a patient presenting with mastitis?

Mastitis Workup and Treatment

Initial Clinical Diagnosis

Mastitis is a clinical diagnosis requiring focal breast tenderness, erythema or hyperpigmentation, fever, and malaise—no laboratory tests or imaging are needed for uncomplicated cases. 1

• Diagnosis is made based on clinical presentation alone in typical lactational mastitis 1
• Look specifically for: unilateral focal breast tenderness, overlying skin changes (erythema in lighter skin, hyperpigmentation in darker skin), fever, and systemic symptoms like malaise 1
• Timing matters: lactational mastitis typically occurs within the first 3 months postpartum with an incidence of approximately 10% 1, 2

When to Obtain Additional Workup

Milk Cultures

• Consider obtaining milk cultures to guide antibiotic therapy, particularly if initial treatment fails 1
• Cultures help identify causative organisms (most commonly Staphylococcus aureus and Streptococcus species) 1, 2

Breast Ultrasound

• Perform ultrasound in immunocompromised patients or those with worsening/recurrent symptoms to identify abscess formation 1
• Approximately 10% of mastitis cases progress to breast abscess, which requires drainage 3, 2
• Ultrasound is the imaging modality of choice when abscess is suspected 1

Critical Red Flag: Rule Out Inflammatory Breast Cancer (IBC)

If a patient has been diagnosed with "mastitis" that has NOT responded to at least 1 week of antibiotics, inflammatory breast cancer must be excluded. 4

• IBC presents with erythema occupying at least one-third of the breast, with or without a palpable mass 4
• Duration of symptoms typically no more than 6 months 4
• Workup for suspected IBC includes:
  • Bilateral diagnostic mammogram with ultrasound of breast and regional lymph nodes 4
  • Core needle biopsy of any underlying mass or abnormal tissue 4
  • Punch biopsy of the skin (at least two biopsies recommended) to evaluate for dermal lymphovascular invasion 4
  • If malignancy confirmed: systemic staging with CT chest/abdomen/pelvis and bone scan 4

Treatment Algorithm

Step 1: Conservative Management (First 24-48 Hours)

Begin with a 1-2 day trial of conservative measures before prescribing antibiotics, as most mastitis is inflammatory rather than infectious. 1

• NSAIDs (ibuprofen, diclofenac, naproxen) for pain and inflammation 5, 1
• Ice application to affected breast 1
• Continue breastfeeding directly from the affected breast—this is essential for treatment 3, 1, 2
• Minimize pumping (avoid overstimulation which can worsen inflammation) 1
• Avoid heat application, aggressive breast massage, and excessive pumping as these worsen the condition 1

Step 2: Antibiotic Therapy (If No Improvement After 24-48 Hours)

If symptoms do not improve with conservative measures, prescribe narrow-spectrum oral antibiotics targeting Staphylococcus aureus and Streptococcus species. 3, 1, 2

• First-line antibiotics:
  • Dicloxacillin 2
  • Cephalexin 2
• Consider methicillin-resistant S. aureus (MRSA) coverage if risk factors present or if initial therapy fails 2
• Most patients can be treated as outpatients with oral antibiotics 1

Step 3: Escalation to Inpatient Management

Hospitalize patients with worsening symptoms, concern for sepsis, or systemic involvement (high fever with chills). 3, 1

• Inpatient management includes:
  • IV antibiotics targeting S. aureus 3
  • Continued breastfeeding or milk expression (provide breast pump if separation occurs) 3
  • Pain management with appropriate analgesics 3
  • Access to trained lactation support staff 3

Step 4: Management of Complications

If abscess develops (identified by ultrasound), drainage is required via needle aspiration or surgical incision. 3, 2

• Breastfeeding can continue on the affected side as long as the infant's mouth does not contact purulent drainage 3, 2
• Discontinuing breastfeeding worsens mastitis and increases abscess risk 3

Common Pitfalls to Avoid

• Do not delay evaluation if mastitis fails to respond to antibiotics within 1 week—this mandates workup for inflammatory breast cancer 4
• Do not recommend heat application, aggressive massage, or excessive pumping—these practices increase tissue trauma and worsen inflammation 1
• Do not advise stopping breastfeeding—continued milk removal is essential for resolution 3, 1, 2
• Do not use probiotics—evidence does not support their use for treatment or prevention 1
• Do not assume all breast erythema is simple mastitis—always consider IBC in the differential, especially if symptoms are atypical or non-responsive 4

Prevention Strategies

• Optimize breastfeeding technique with proper infant latch 1, 2
• Encourage physiologic breastfeeding rather than pumping when possible 1
• Avoid overstimulation of milk production 1
• Consider lactation consultant referral for technique optimization 2