MDM Templates

Mastitis — Discharge

Patient presents with breast pain, erythema, and warmth consistent with mastitis.
Well appearing without signs of abscess on exam. No fluctuance or concerning features for necrotizing infection.
History and exam lower suspicion for breast abscess, inflammatory breast cancer, or Paget disease.
Plan:
– Dicloxacillin 500 mg QID for 10 days (or Keflex 500 mg QID if preferred).
– Continue breastfeeding/pumping.
Disposition: Discharge with PCP/OB follow-up in 48–72 hours.
Return for worsening erythema, fluctuance, fever, or failure to improve on antibiotics.

---

Breast Abscess — I&D

Patient presents with breast mass with fluctuance consistent with breast abscess.
Ultrasound confirms fluid collection.
Plan: Bedside I&D performed (see procedure note). Packing placed. Bactrim DS BID for 10 days for MRSA coverage.
Disposition: Discharge with surgery or OB follow-up in 48 hours for packing removal.
Return for worsening symptoms or signs of systemic infection.

---

Breast Mass — Workup Indicated

Patient presents with breast mass without signs of acute infection. No skin changes suggestive of inflammatory carcinoma.
Plan: Outpatient diagnostic mammogram and ultrasound.
Disposition: Discharge with prompt PCP and breast surgery referral.
Return for rapid growth, skin changes, or new symptoms.

Procedure Notes

Breast Abscess Incision and Drainage (I&D)

Indication: Confirmed or highly suspected breast abscess with fluctuance and/or imaging confirmation of fluid collection.

Preparation: Patient positioned supine with affected breast exposed. Skin prepped with chlorhexidine or iodine-based antiseptic in widening circles. Local anesthesia: 1% lidocaine with epinephrine infiltrated around incision site and into cavity. Consider topical numbing cream if time permits.

Technique: Make a small incision (1–2 cm) overlying point of maximal fluctuance or guided by ultrasound. Direct incision toward nipple-areolar complex along skin lines when possible. Express purulent drainage. Gently probe cavity with gloved finger or small hemostat to break down loculations. Irrigate with normal saline. Place iodoform gauze packing loosely into cavity to maintain drainage. Do not pack too tightly; loose packing encourages continued drainage and healing from inside out.

Aftercare: Gauze dressing changed daily. Patient instructed on wound care and signs of infection. Antibiotic coverage: Bactrim DS (sulfamethoxazole-trimethoprim) BID for 10 days covers common pathogens including MRSA and streptococci. Packing removed at follow-up in 48 hours (can be done in ED, surgery clinic, or OB office depending on disposition).

Pearls: Do not pack too aggressively—gentle, loose packing facilitates drainage. Needle aspiration alone may be attempted for first occurrence if patient can tolerate close follow-up, but formal I&D is standard for clear abscess. Repeat imaging not routinely needed if clinical improvement on antibiotics and drainage. Recurrent abscesses may warrant evaluation for underlying predisposition (e.g., diabetes, immunosuppression) or malignancy.

Clinical Education

Mastitis vs Abscess: Clinical Distinction and When to Image

Mastitis presents as breast pain, erythema, warmth, and induration, typically without a discrete fluid collection. Exam demonstrates diffuse cellulitis without fluctuance. Patients are often febrile but generally well-appearing and respond well to oral antibiotics within 48–72 hours. Ultrasound is not routinely needed for uncomplicated mastitis if the clinical presentation is classic and exam is reassuring for abscess. Imaging is indicated when mastitis fails to improve on antibiotics, when fluctuance develops, or when abscess is suspected on clinical grounds.^[1]

Breast abscess presents with localized fluctuance or imaging confirmation of a fluid collection. Patients may have fever and systemic symptoms but the key distinction is the presence of pus, not just cellulitis. Ultrasound is the first-line imaging modality and is highly sensitive for fluid collections >1 cm. Once abscess is confirmed, drainage (either needle aspiration or surgical I&D) is required; antibiotics alone cannot resolve an abscess. Imaging is essential in this case to guide intervention.

Antibiotic Selection: Dicloxacillin vs Keflex vs Bactrim and MRSA Coverage

Dicloxacillin 500 mg QID or Keflex 500 mg QID are both reasonable first-line agents for non-toxic-appearing mastitis in non-lactating patients or when lactating and MRSA is not suspected. Both cover streptococci and sensitive staphylococci. Dicloxacillin is a beta-lactam antibiotic with excellent breast tissue penetration. Keflex (cephalexin) is a first-generation cephalosporin and also penetrates breast tissue well. Neither provides reliable MRSA coverage.^[2]

Bactrim DS (sulfamethoxazole-trimethoprim) BID for 10 days is preferred when MRSA is suspected or confirmed, such as in recurrent mastitis, recent antibiotic exposure, intravenous drug use history, or failed first-line therapy. Bactrim provides MRSA coverage and also covers many gram-negative organisms. Lactating mothers taking Bactrim should monitor infants for rash and jaundice but brief use is generally considered safe. For nonlactating patients, Bactrim remains a solid MRSA option. In hospital settings with suspected CA-MRSA, consider clindamycin 300–450 mg TID or cloxacillin if available.

In abscess management, Bactrim DS is the standard choice after drainage because it provides both MRSA and streptococcal coverage and penetrates well into purulent fluid. The combination of surgical drainage plus systemic antibiotics is essential; antibiotics alone will fail.

Breast Abscess Management: I&D Technique, Needle Aspiration vs Incision, and Packing

Needle aspiration under ultrasound guidance can be attempted for small, first-episode abscesses (especially in motivated, reliable patients with close follow-up capability) and may be curative in 30–40% of cases. The advantage is less scarring and simpler bedside procedure. However, success is not guaranteed, and repeat procedures are sometimes needed. For larger abscesses, complex cavities, or patient factors that limit follow-up, needle aspiration is less appropriate.^[3]

Incision and drainage (I&D) is the gold standard for breast abscess in the ED setting. A small incision (1–2 cm) is made overlying fluctuance, pus is expressed, and the cavity is gently explored to break down loculations. Iodoform gauze packing is placed loosely to keep the cavity open and promote continued drainage from inside out. Tight packing should be avoided as it may trap infection and impede healing. Packing is typically removed in 48 hours at follow-up (can be at bedside, in clinic, or in OR depending on disposition).

Packing technique is crucial: use loose, ribbon-style iodoform gauze loosely packed into the cavity. The goal is to maintain drainage, not to fill the space completely. As healing progresses, the cavity epithelializes from the base outward and inward, eventually closing. Some experts advocate for packing removal as early as 24–48 hours once acute drainage has slowed.

Lactational vs Non-Lactational Abscess: Key Differences

Lactational abscesses occur in breastfeeding mothers, usually within 6 months postpartum, and are often preceded by mastitis or milk duct obstruction. The predominant organisms are Staphylococcus aureus (including MRSA), Streptococcus agalactiae, and oral flora. Management involves drainage, continued lactation (or pump if painful), and antibiotics. Patients should continue breastfeeding or pumping from the affected breast if possible to help prevent milk stasis and recurrence; this is safe as long as antibiotics are appropriate and there is no concern for systemic infection in the infant.

Non-lactational abscesses are less common and occur in non-breastfeeding women, often with underlying breast disease, chronic inflammation (squamous metaplasia), or malignancy. They may involve anaerobes and gram-negative organisms in addition to staphylococci. These abscesses tend to be deeper, more chronic, and more likely to recur, requiring closer follow-up and imaging (mammogram, ultrasound) to evaluate for underlying malignancy or pathology. Non-lactational abscess warrants closer surveillance and consideration of diagnostic imaging beyond acute management.

Red Flags and When to Worry: Inflammatory Breast Cancer, Necrotizing Fasciitis, and Paget Disease

Inflammatory breast cancer (IBC) presents with breast erythema, edema, and dimpling (“peau d’orange”) but is a malignancy, not infection. History is key: rapid onset of erythema over days to weeks, often without systemic toxicity. The erythema is often non-blanching and may be accompanied by skin thickening. No response to antibiotics is a red flag. Mammography and biopsy are needed. If IBC is in the differential (especially in older women, rapid progression, failure to respond to antibiotics, or abnormal skin appearance), arrange urgent imaging and oncology referral.

Necrotizing fasciitis is rare in the breast but presents with rapidly progressive erythema, crepitus, severe pain disproportionate to exam findings, and systemic toxicity (fever, tachycardia, altered mental status). Gas-forming organisms (polymicrobial, Clostridium) can cause crepitus. Risk factors include trauma, immunosuppression, and diabetes. Necrotizing fasciitis requires emergent surgical consultation and broad-spectrum IV antibiotics; do not delay for imaging. Look for crepitus, severe toxicity, or pain out of proportion to findings.

Paget disease of the breast presents with unilateral nipple erythema, erosion, and discharge, often mimicking eczema or infection. It is a form of breast cancer (usually ductal carcinoma in situ). Biopsy is required for diagnosis. Suspect Paget disease if nipple findings are unilateral, persistent, fail to improve on topical therapy, or are accompanied by an underlying mass. Referral to breast surgery is warranted.

References

1. Amir LH. “Mastitis and Abscess of the Breast.” UpToDate, 2025. Diagnostic approach and distinction between mastitis and abscess.
2. Infectious Diseases Society of America (IDSA). “Clinical Practice Guidelines for Skin and Soft Tissue Infections.” Clin Infect Dis, 2016. Antibiotic selection and dosing for breast infections.
3. Karamachtsis A, et al. “Management of Breast Abscess: Current Techniques.” J Surg Res, 2018; 231:210–216. Comparison of needle aspiration and incision/drainage outcomes.