Neonatal Mastitis

Neonatal MastitisWe have previously discussed my distrust of neonates (ALTE, BRUE) and this may be why so many of the Morsels focus on neonatal issues. Recently a dear friend, colleague, and full-time appreciator of UMMS Shock Trauma Pink Scrubs, Dr. Jessica Baxley brought up the topic of Mastitis in a Neonate! Is this another topic like Neonatal Conjunctivitis (something that seems simple, but is made complex by the fact it is in a neonate) or is it straight forward? Let us take a minute to review Neonatal Mastitis:


Neonatal Breast Enlargement

  • Neonatal breast enlargement is a common and normal finding. [Masoodi, 2014]
    • At the end of pregnancy, the falling levels of estrogen can trigger a release of prolactin from the newborn’s pituitary.
    • Leads to breast enlargement in ~70% of neonates.
  • Typically affects: [Masoodi, 2014]
    • Full Term infants (premature infants have less well developed breast tissue)
    • Both males and females equally.
    • Neonates during in the first week of life.
      • May last longer in females.
  • Some will demonstrate discharge from the nipple.
    • This should be milky or clear fluid.
    • Often referred to as “Witch’s Milk” – but let us not be judgmental.
  • The condition is self-limited and warrants only observation.
    • Observation for signs of developing infection.
    • Can become complicated by infection and abscess formation.


Neonatal Mastitis: Basics

  • Mastitis, as the name would imply, is an infection of the breast tissue.
  • Unlike normal breast enlargement in a neonate, mastitis will be: [Masoodi, 2014; Sloan, 2003]
    • Red
    • Painful
    • More likely in females (2:1)
    • Purulent discharge from nipple
    • Most often unilateral [Sloan, 2003]
    • Potentially associated with suppurative lesions elsewhere [Masoodi, 2014]
  • Typically seen in 2nd – 8th week of life. [Masoodi, 2014; Ruwaili, 2012; Sloan, 2003]
    • Uncomplicated Mastitis is usually earlier (2nd – 3rd week).
    • Abscesses have been seen in 3rd and 4th week of life.
  • It has been found to most often a localized process. [Masoodi, 2014]
    • Occurs in well appearing infants without systemic symptoms.
      • 8-28% have presented with systemic symptoms. [Masoodi, 2014; Sloan, 2003]
      • Fever, vomiting, lethargy or irritability are uncommon. [Ruwaili, 2012]
    • Blood cultures and CSF cultures, when done, have not proven to be positive in reported cases. [Masoodi, 2014; Ruwaili, 2012]
  • Most often it is associated with S. aureus.
    • May also see Group B Strep, Gram-negative enteric, or anaerobic bacteria.


Neonatal Mastitis: Management

  • 1st – Don’t call normal neonatal breast enlargement “mastitis.”
  • 2nd – Don’t trust a neonate, but… 
  • 3rd – Be reasonable though.
    • While remaining vigilant and not trusting the neonate, it has been well documented that neonates with isolated mastitis do well with limited work-up and antibiotics. [Masoodi, 2014; Ruwaili, 2012]
    • There is no standard approach with respect to “full-sepsis work-up” vs “limited-sepsis work-up.” [Ruwaili, 2012]
      • Not trusting the neonate, certainly warrants a more conservative approach, but again, this is usually localized pathology.
      • There is significant variation in physician’s management of mastitis. [Ruwaili, 2012]
    • There is also no standard approach with respect to IV antibiotics vs oral (Inpatient vs Outpatient). [Ruwaili, 2012]
      • Most studies to show a higher prevalence of inpatient IV antibiotics over outpatient management.
      • Oral antibiotics may have poor bioavailability in the neonatal period.
      • Personally, a neonate with a “suspected” infection makes me nervous… one with a KNOWN infection makes me diaphoretic.
    • The available evidence, though, would note that the non-toxic infant without systemic symptoms presenting with mastitis does not benefit from extensive testing. [Ruwaili, 2012]
    • Gram stain and Culture of any nipple discharge fluid will not likely help during the initial evaluation, but may be beneficial if there is treatment failure.
    • While abscesses typically require incision and drainage, there is evidence that trial of antibiotics is reasonable prior to either needle aspiration or incision and drainage of neonatal mastitis. [Sloan, 2003]


Moral of the Morsel

  • Never trust a neonate. Just simply, never trust a neonate, but you can be reasonable.
  • Breast enlargement in a neonate is normal. Breast infection is not. Mastitis requires antibiotics.
  • If giving a neonate antibiotics, ask yourself whether you need to worry about disseminated infection.



Masoodi T1, Mufti GN2, Bhat JI3, Lone R1, Arshi S1, Ahmad SK1. Neonatal mastitis: a clinico-microbiological study. J Neonatal Surg. 2014 Jan 1;3(1):2. PMID: 26023473. [PubMed] [Read by QxMD]

Al Ruwaili N1, Scolnik D. Neonatal mastitis: controversies in management. J Clin Neonatol. 2012 Oct;1(4):207-10. PMID: 24027728. [PubMed] [Read by QxMD]

Borders H1, Mychaliska G, Gebarski KS. Sonographic features of neonatal mastitis and breast abscess. Pediatr Radiol. 2009 Sep;39(9):955-8. PMID: 19506847. [PubMed] [Read by QxMD]

Faden H1. Mastitis in children from birth to 17 years. Pediatr Infect Dis J. 2005 Dec;24(12):1113. PMID: 16371879. [PubMed] [Read by QxMD]

Sloan B1, Evans R. Clinical pearls: neonatal breast mass. Acad Emerg Med. 2003 Mar;10(3):269-70. PMID: 12615593. [PubMed] [Read by QxMD]
Efrat M1, Mogilner JG, Iujtman M, Eldemberg D, Kunin J, Eldar S. Neonatal mastitis–diagnosis and treatment. Isr J Med Sci. 1995 Sep;31(9):558-60. PMID: 7558780. [PubMed] [Read by QxMD]

Tzen KT, Wu WH, Shih HY. Mastitis neonatorum. Zhonghua Min Guo Xiao Er Ke Yi Xue Hui Za Zhi. 1989 Jul-Aug;30(4):248-53. PMID: 2637605. [PubMed] [Read by QxMD]


Sean M. Fox
Sean M. Fox
Articles: 583


  1. There is significant disagreement among clinicians regarding the best way to treat the well-looking neonate with localized mastitis. Most elect to perform blood tests and start treatment with IV antibiotics with good Staphylococcus aureus coverage, followed by oral antibiotics if cultures are negative.

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