2.1 Study population
The study included breastfeeding women with acute mastitis who were
treated in Ningbo Medical Center Lihuili Hospital between January 2016
and August 2018. The inclusion criteria were the followings: (1) every
patient was diagnosed with acute mastitis according to the widely
accepted criteria of mastitis (see below); (2) blood sample for SLCs was
routinely obtained in all patients directly or shortly after
presentation to the ED, and if there was any suspicion of breast
abscess, diagnostic breast ultrasound was performed; (3) conservative
treatments including breast massage for emptying the breast, ibuprofen
for analgesia, a hot compress applied prior to breastfeeding for
stimulating milk flow, and a cool compress applied after breastfeeding
for reducing swelling and pain, were performed on every patient; (4)
common breast signs, including inflammatory characteristics of redness,
swelling, heat and pain in the breast and systemic symptoms, including
fever, chill, nausea and vomiting, were documented in medical records;
(5) follow-up data were necessary, including the name of the antibiotic,
the duration of the antibiotic, and the treatment outcome. If women
attended the hospital for more than one episode of mastitis, we included
only the first admission. The exclusion criteria included the
followings: (1) nonpostpartum mastitis; (2) special breast inflammation,
including plasma cell mastitis (PCM), granulomatous lobular mastitis
(GLM) and breast tuberculosis; (3) the presence of breast abscess before
treatment; (4) inflammatory breast carcinoma (IBC) with similar breast
signs to acute mastitis; and (5) having received medicinal management
for current mastitis before visiting the emergency department. The
principles outlined in the Declaration of Helsinki were followed,and
written informed consent was obtained from every patient.