The ABM protocol on mastitis

The ABM protocol on mastitis

The Academy of Breastfeeding Medicine (ABM) publishes protocols to make it easier for health care professionals who care for breastfeeding mothers to stay up-to-date and promote best practices in care for breastfeeding mothers and their children. In 2014 the Academy published a protocol on mastitis, the ABM Clinical Protocol #4: Mastitis (1), written by Dr Lisa Amir, who has also been one of the speakers in the 1st LactApp Medical Congress last May. This year, the ABM has published a new protocol on mastitis, the ABM Clinical Protocol #36: The Mastitis Spectrum (2), which introduces different definitions and concepts and proposes new strategies for the management of mastitis.

From the LactApp clinical team, we wanted to compare them and highlight the most important differences, so in this article, we will focus on comparing the definition of mastitis between both protocols.

In the old protocol (#4 Mastitis), mastitis was considered a single pathological entity and was defined as an inflammation of the breast, and this inflammation could be or not be related to a bacterial infection. Therefore, it clinically defines mastitis as the appearance of a tender, warm, swollen, wedge-shaped area associated with a temperature of 38.5°C or higher, chills, flu-like pain and systemic disease.

In the current protocol (#36 The Mastitis Spectrum) it states that mastitis encompasses a spectrum of conditions resulting from ductal inflammation and stromal oedema. This spectrum of mastitis includes ductal narrowing (obstructions), inflammatory mastitis, bacterial mastitis, phlegmon, abscess, galactocele, and subacute mastitis and defines as follows:

  • Narrowing or obstructions of the ducts: Inflammation and narrowing of the duct that is related to alveolar distension and/or mammary dysbiosis.
  • Inflammatory mastitis: Develops when obstructions persist or worsen, and surrounding inflammation progresses. Inflammatory mastitis presents as an increasingly erythematous, edematous and painful region of the breast with systemic signs and symptoms such as fever, chills and tachycardia. The protocol emphasizes that systemic inflammatory response syndrome can occur without infection.
  • Bacterial mastitis: represents a progression from ductal narrowing and inflammatory mastitis to a situation that requires antibiotics or probiotics to resolve. The most common organisms in lactation mastitis include Staphylococcus (e.g., S. aureus, S. epidermidis, S. lugdunensis and S. hominis) and Streptococcus (e.g., S. mitis, S. salivarius, S. pyogenes and S. agalactiae).
  • Phlegmon: Phlegmon collections of fluid that are heterogeneous and complex and may appear throughout the body when inflammation occurs. Phlegmon may be suspected when mastitis worsens with the appearance of a firm, mass-like area without fluctuance.
  • Abscess: An accumulation of infected fluid that needs to be drained. It develops from the progression of bacterial mastitis or phlegmon.
  • Galactocele and infected galactocele: A galactocele develops when the narrowing of ducts obstructs milk flow to the point that a significant volume of obstructed milk accumulates in a cyst-like cavity.
  • Subacute mastitis: Chronic mammary dysbiosis with the appearance of bacterial biofilms that narrow the ductal lumens. Coagulase-negative staphylococci and viridans streptococci (i.e., S. mitis and S. salivarius) form thin biofilms that line the epithelium of the mammary ducts. When these bacterial species proliferate, they can form thick biofilms inside the ducts, inflaming the mammary epithelium and forcing milk to pass through an increasingly narrow lumen.

The old protocol associated symptoms of sensation of nipple burning or burning pain in the breast with a thrush infection (candida). However, the new protocol asserts that there is insufficient scientific evidence to support this diagnosis and attributes it to an alteration within the mastitis spectrum.

It should be noted that the definition of mastitis is still very controversial, and there is no international medical consensus that defines mastitis. There is a lack of rigorous, well-designed clinical studies on the pathophysiology of mastitis and the studies that do exist are contradictory. Furthermore, in the last 3 years, there has not been any significant scientific contribution to the field.


1. Amir LH. ABM clinical protocol #4: Mastitis, revised March 2014. Breastfeed Med [Internet]. 2014;9(5):239–43.

2. Mitchell KB, Johnson HM, Rodríguez JM, Eglash A, Scherzinger C, Zakarija-grkovic I, et al. Academy of Breastfeeding Medicine Clinical Protocol #36: The Mastitis Spectrum, Revised 2022. Breastfeed Med [Internet]. 2022;17(5):360–76.

Leave a Reply

Your email address will not be published. Required fields are marked *