Mastitis and Breast Abscesses

Authors: Sarah Iosifescu, MD (EM Resident Physician, St. Luke’s-Mount Sinai West) and Chen He, MD (Program Director and Assistant Professor Emergency Medicine, St. Luke’s-Mount Sinai West) // Reviewed by: Edward Lew, MD (@elewMD); Alex Koyfman, MD (@EMHighAK); and Brit Long, MD (@long_brit)

Clinical Cases:  

Case 1: A 55-year-old woman, with a history of hypertension and a 20-pack year smoking history, presents with fever, chills, and a painful breast for three days. She woke up three days ago and noted her right breast felt extremely swollen. The next day, she felt feverish and noted her breast had become red. She took some Tylenol which mildly improved her symptoms, but today she is in excruciating pain. She denies being pregnant and any similar symptoms in the past. She denies recent weight loss, changes in appetite, or discharge from the nipple. She states the area is painful but not itchy.

Vital signs are HR 104, BP 130/75, RR 20, SpO2 100% on RA, and Temp 101.5°F. Her exam is notable for a 3 cm in diameter circular area of erythema, edema, warmth, tenderness and induration on the medial portion of her right breast. There are no palpable lymph nodes in the axillae or supraclavicular area, and nothing can be expressed from the area. There is no ‘peau d’orange’ appearance, her nipples are not retracted, and you do not appreciate any dimpling of the area. What do you do next?

Case 2: A 32-year-old woman, G2P2 with no past medical history, who gave birth three weeks ago, presents with left breast pain for three days. It is red, swollen, and painful. She went to her OB-GYN yesterday who started her on cephalexin 500 mg four times per day. She has been taking the antibiotics as prescribed but reports no improvement. She is actively breastfeeding and is worried that this could affect her baby.

Vital signs are HR 85, BP 115/70, RR 18, SpO2 100% on RA, and Temp 100.4°F. Her exam is notable for a 2 cm in diameter round area of erythema, edema, warmth, and induration over the lateral superior portion of her left breast. There is no nipple discharge, her nipples are not retracted, she has no ‘peau d’orange’ appearance and you do not appreciate any lymph nodes in the supraclavicular or axillary regions. What are your next steps?


Mastitis in general refers to inflammation of the breast parenchymal tissue and can be broken down into what is known as a puerperal mastitis (mastitis in the setting of lactation) and non-puerperal mastitis (mastitis not related to lactation). There are rare cases of granulomatous mastitis which are complications of tuberculosis or sarcoidosis.1 Breast erythema, pain, and warmth can also be present during breast engorgement or when a duct is blocked but with the absence of systemic symptoms.3 The clinical definition of mastitis is generally considered to be infection of breast tissue, with the breast being “red, swollen, warm and painful in one specific area…and may cause flu like symptoms, such as fever, aches, and fatigue.”Breast abscess is defined as a collection of pus in the breast tissue. Breast abscesses often occur as a complication of mastitis. There appears to be a spectrum from breast engorgement, non-infective mastitis, infective mastitis, and ultimately breast abscess.4

Puerperal mastitis leading to breast abscess is often due to infections with Staphylococcus aureus and Streptococcus species. The bacteria usually spread from an infant’s nares or pharynx through a break in the nipple areolar skin.5 Mastitis occurs in 1-24% of lactating women, and breast abscesses occur in 5-11% of lactating women who develop infectious mastitis. It most commonly occurs within the first 6 weeks of breastfeeding; however, it can occur at any time during breastfeeding.4 The breast tissue normally appears erythematous, is indurated, and feels warm to the touch. Predisposing factors include damaged nipple tissue, missing feedings, oversupply of milk, poor attachment by infant, pressure on the breast, maternal stress, or fatigue.



Mastitis is a clinical diagnosis. Laboratory tests and diagnostic procedures do not need to be routinely preformed. Per the WHO report on mastitis, breastmilk culture should be obtained if:

  • No response to antibiotics in 2 days
  • Mastitis recurs
  • Hospital acquired mastitis
  • Patient is allergic to usual therapeutic antibiotics
  • Severe or unusual cases3

Treatment of mastitis includes counseling, effective milk removal, antibiotics, and symptomatic treatment. Patients need to be reassured that they can continue to breast feed from the affected breast, that it will not affect the baby, and that in fact it will help the breast to recover. They also need to be counseled on effective milk removal, which is a critical part of treatment. This includes improving latching of the infant, frequent breastfeeding (in both frequency and length of feed as required by the infant), and in some cases using hand expression or pumping. Symptomatic treatment includes non-steroidal anti-inflammatory medications and cold compresses. Antibiotics should cover Staphylococcus aureus. First line antibiotics are dicloxacillin 500 mg by mouth four times per day for 7-10 days or cephalexin 300-450 mg by mouth three times a day for 7-10 days. If patients do not respond to initial treatment, MRSA should be considered, and antibiotics should include trimethoprim-sulfamethoxazole by mouth twice daily for 5-14 days or clindamycin 300 mg by mouth three times per day for 5-14 days.7

Breast abscess

Breast abscess can be concurrent with mastitis or an abscess can develop five days to four weeks after a patient has developed mastitis.4  The diagnosis of breast abscess is made clinically; symptoms include inflammation of breast tissue with fever, a palpable mass that is tender and fluctuant, and a fluid collection demonstrated on ultrasound. The other differentials to consider for breast abscess in lactating women include 1) a plugged duct without systemic symptoms, 2) galactocele, which is a cystic non-tender mass, and 3) inflammatory breast cancer which usually has skin thickening, erythema, and peau d’orange appearance.7

Females who are non-lactating can also develop mastitis and/or breast abscesses. It is important to differentiate mastitis in the non-lactating female from inflammatory breast cancer, which is a rare form of breast cancer but can present similarly to mastitis with diffuse erythema and edema of the breast tissue. Mastitis, however, generally causes a fever and responds to antibiotics differentiating it from inflammatory breast cancer.8 Smoking is a risk factor for non-puerperal mastitis and abscess formation due to damage of the breast ducts. In a series of 60 patients with recurrent sub-areolar breast abscesses it was found there is a 26.4 times increased risk of developing breast abscess for heavy smokers.10 The pathogens in non-puerperal mastitis are usually Staphylococcus aureus, Enterococci, and Bacteroides.9

For the emergency physician, if mastitis is detected prior to development of an abscess, outpatient antibiotics with follow up with their ob-gyn or primary care is appropriate. If a patient is non-lactating and does not have systemic symptoms, referring to a breast radiologist or breast surgeon would be appropriate for ensuring this is mastitis and not inflammatory breast cancer. In the lactating patient with mastitis, if the patient has had symptoms for less than 24 hours, it is reasonable to encourage them to focus on effective removal of milk for a day or two prior to starting antibiotics. However, if there is concern for abscess in either lactating or non-lactating patients, drainage and antibiotics are imperative. Physical exam should include thorough examination of the breast tissue, lymph node exam, assessment of nipple discharge, and skin exam. Bedside ultrasound or formal ultrasound can assist with assessing if there is a breast abscess.

Historically, breast abscesses were treated with incision and drainage, oftentimes at bedside. However, this is invasive and often results in scarring, possible structural damage, and poor cosmetic outcomes. Fine needle aspiration under direct visualization, usually by a breast radiologist, is the preferred method of drainage.11 At times repeated needle aspirations may be necessary. Abscesses that are larger than 5 cm, have a large volume of aspirated pus on needle aspiration, or have a significant delay in treatment are risk factors for failure of needle aspiration and may require surgical incision and drainage.11 Surgical drainage is appropriate if there is pressure necrosis or ischemia of the overlying skin and/or if the abscess is large and/or there are multiple abscesses.4,7

Emergency physicians often do not drain breast abscesses due to the sensitivity of breast tissue and cosmetic concerns. If the emergency physician is comfortable with needle aspiration, it is an uncomplicated small abscess (generally less than 3 cm) that isn’t deep, and there is no immediate follow up available, the emergency physician can consider performing needle aspiration. Ideally patients with abscess should be referred to breast radiology or breast surgery for abscess drainage while the emergency room physician starts them on antibiotics, which should include coverage for MRSA.

Case Conclusion

Case 1: This patient meets sepsis criteria with a heart rate of 104 and temperature of 101.5°F. You order sepsis protocol labs which include blood cultures, a complete blood count, basic metabolic panel, and venous blood gas. She has a lactate of 3.5, and you decide she likely needs to be admitted. You start her on fluids and IV vancomycin and order a formal ultrasound to assess for breast abscess. ­The ultrasound shows a 4 cm-deep breast abscess. You consult general surgery, and they perform needle aspiration under ultrasound guidance. The patient is admitted to the hospital to the medicine service for sepsis. You follow up on the patient who ultimately needed three different ultrasound aspirations for complete drainage. The patient also had a mammogram while in the hospital to rule out inflammatory breast cancer given she had non-puerperal mastitis although the suspicion was low given the patient had been febrile and responded well to antibiotics.

Had the patient not met sepsis criteria and not warranted admission, you would have started her on outpatient antibiotics and arranged outpatient follow up with either a breast surgeon or breast radiologist for drainage.

Case 2: You clinically diagnose the patient with mastitis given her history of a painful breast while breast feeding accompanied by a fever. However, you are concerned based on her physical exam that she also has an abscess and suspect this is why she hasn’t responded to the cephalexin prescribed by her ob-gyn. You take a look with bedside ultrasound and can appreciate a 2 cm collection under the breast tissue.  You arrange for her to follow up with next day with the breast clinic for drainage. The patient is afraid that this abscess can affect her baby, and you reassure her she should continue to breast feed from the affected breast to improve her mastitis. You ask one of the labor and delivery lactation consultants to come speak to her to make sure that she is optimizing her breast feeding to decrease the risk of recurrent mastitis. The patient is discharged home on dicloxacillin 500mg four times daily for 7 days and follows up in breast clinic the next day for ultrasound guided needle aspiration.


  • Mastitis refers to erythema and edema of breast tissue PLUS systemic signs and symptoms.
  • Mastitis can be categorized as puerperal (breastfeeding) vs. non-puerperal (not breast feeding).
  • In patients that have non-puerperal mastitis, it is imperative to consider inflammatory breast cancer as a possibility.
    • If patient has fever and responds to antibiotics, this is less likely.
    • However, from the ED refer to breast surgery or breast radiology to ensure appropriate follow up if patient doesn’t respond to antibiotics.
  • In the puerperal patient there is a spectrum from a plugged breast duct developing into mastitis developing into breast abscess.
    • Early mastitis (<24 hours) counseling on effective milk drainage (increased feedings by infant in addition to pumping) can be considered prior to starting antibiotics.
  • For either puerperal or non-puerperal mastitis.
    • Antibiotics covering S. aureus should be initiated, such as dicloxacillin.
    • If the patient has developed an abscess, general surgery and/or breast radiology should be consulted for drainage if these resources are available. If not and the abscess is uncomplicated, small and superficial the emergency physician can consider performing ultrasound guided needle aspiration.
    • If the patient is hemodynamically stable with a breast abscess, she is safe for discharge with outpatient follow up with breast surgery or breast radiology for drainage but should be started on antibiotics from the ED.

References/Further Reading:

  1. Gaillard F. Mastitis: Radiology Reference Article. Radiopaedia Blog RSS. Accessed September 13, 2019.
  2. Women’s Health Care Physicians. ACOG. Accessed September 17, 2019.
  3. World Health Organization. Mastitis: Causes and Management. Publication number WHO/FCH/CAH/00.13. World Health Organization, Geneva, 2000
  4. Amir LH; Academy of Breastfeeding Medicine Protocol Committee. ABM clinical protocol #4: Mastitis, revised March 2014. Breastfeed Med. 2014;9(5):239–243. doi:10.1089/bfm.2014.9984
  5. Skandhan AKP. Puerperal mastitis: Radiology Reference Article. Radiopaedia Blog RSS. Accessed September 17, 2019.
  6. Dixon, J. Lactational Mastitis. In: UpToDate, Post, TW (Ed), UpToDate, Waltham, MA, 2014.
  7. Dixon, J. Primary Breast Abscess. In: UpToDate, Post, TW (Ed), UpToDate, Waltham, MA, 2014.
  8. Taghian, A et al. Inflammatory breast cancer: Clinical features and Treatment. In: UpToDate, Post, TW (Ed), UpToDate, Waltham, MA, 2014.
  9. Bagenal J, Bodhinayake J, Williams KE. Acute painful breast in a non-lactating woman. The BMJ. Published June 15, 2016. Accessed September 20, 2019.
  10. Schäfer P, Fürrer C, Mermillod B. An Association of Cigarette Smoking with Recurrent Subareolar Breast Abscess. International Journal of Epidemiology. 1988;17(4):810-813. doi:10.1093/ije/17.4.810
  11. Eryilmaz R, Sahin M, Tekelioglu MH, Daldal E. Management of lactational breast abscesses. The Breast. 2005;14(5):375-379. doi:10.1016/j.breast.2004.12.001.

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