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Nipple Discharge: Causes, Evaluation, and When to See a Doctor

Disclaimer: This information is educational, not medical advice. Any nipple discharge warrants clinical evaluation.

Common Causes

  • Physiologic: Milky discharge (galactorrhea) from nipple stimulation, pregnancy, or medications (antipsychotics, SSRIs, antihypertensives) that elevate prolactin.
  • Benign Breast Conditions: Duct ectasia (thick, greenish/brown), intraductal papilloma (clear or bloody, single duct), fibrocystic changes.
  • Infection: Periductal mastitis or abscess (purulent, painful).
  • Malignancy: Ductal carcinoma in situ (DCIS) or invasive cancer—especially if unilateral, spontaneous, clear/bloody, from a single duct, in women >40.
  • Endocrine: Hypothyroidism, pituitary prolactinoma.

Red Flags Requiring Prompt Evaluation

  • Spontaneous (without squeezing)
  • Unilateral (one breast only)
  • Clear, serous, or bloody
  • Single-duct origin
  • Associated lump, skin changes, or nipple retraction
  • Age >40 or high-risk history

Diagnostic Approach

  1. Clinical breast exam
  2. Prolactin and TSH levels
  3. Diagnostic mammogram ± ultrasound
  4. Ductography (galactography) or ductoscopy for single-duct discharge
  5. Cytology of discharge (low sensitivity)
  6. Biopsy if imaging suspicious

Bottom line: Most nipple discharge is benign, but never assume—always have it assessed.

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