What are the key clinical features that differentiate physiological from pathological nipple discharge?

Key clinical features differentiating physiological from pathological nipple discharge include the nature, laterality, and associated symptoms of the discharge.

• Physiological nipple discharge is typically bilateral, involves multiple ducts, and is often milky or clear in colour. It is usually non-spontaneous and can be expressed on manipulation. It is commonly associated with hormonal changes such as pregnancy, lactation, or medication effects, and lacks associated breast masses or skin changes NICE NG12.
• Pathological nipple discharge is more likely to be unilateral, spontaneous, and originates from a single duct. The discharge may be bloody, serous, or clear but persistent and often associated with a palpable breast lump, skin changes, or nipple retraction. It is more common in older women and raises suspicion for underlying malignancy or intraductal papilloma Woodard et al. 2025.
• Additional red flags for pathological discharge include discharge that is persistent, spontaneous, unilateral, and bloody or serous, especially if accompanied by a breast mass or skin changes NICE NG12.
• Imaging evaluation is recommended for pathological features to exclude malignancy, whereas physiological discharge without concerning features may be managed conservatively NICE NG12 Woodard et al. 2025.