Nipple Discharge

Fluid emanating from the nipple, a common presenting complaint spanning a broad spectrum from entirely physiological, benign discharge through to a range of pathological causes including, though uncommonly, underlying malignancy.

The essential clinical priority comprises structured, systematic characterisation of the discharge according to specific features: laterality, whether spontaneous or expressed, single or multiple duct origin, and colour.

Collectively, alongside the broader clinical context, these features guide appropriate risk stratification and correspondingly targeted diagnostic evaluation.

Classification framework

• Physiological nipple discharge is typically bilateral, arises from multiple ducts, and is generally only expressible with deliberate manipulation rather than occurring spontaneously. It is a common, entirely benign finding.
• It is particularly relevant in the context of recent pregnancy or breastfeeding, where physiological galactorrhoea can persist for a variable period following cessation of breastfeeding. Less commonly, it reflects simple ductal secretion unrelated to any specific underlying pathology.
• Pathological nipple discharge is generally characterised by features raising greater diagnostic concern: unilateral origin from a single duct, spontaneous occurrence without requiring deliberate expression, and, of particular relevance, blood-stained or frankly bloody character.
• This combination of features carries substantially greater relevance to an underlying, identifiable pathological cause requiring targeted diagnostic evaluation.
• Benign causes of pathological discharge include intraductal papilloma, the commonest specific cause of unilateral, blood-stained, single-duct discharge. Mammary duct ectasia typically produces thicker, variably coloured discharge from multiple ducts in an older woman.
• Uncommonly, the cause is underlying malignancy. Ductal carcinoma in situ is a particularly relevant consideration given its recognised association with this specific presenting symptom.
• Galactorrhoea reflects inappropriate lactation unrelated to pregnancy or recent breastfeeding. It typically presents as bilateral, milky discharge from multiple ducts.
• It warrants specific consideration of an underlying cause including hyperprolactinaemia, certain medications (including antipsychotics and other dopamine antagonists), and, rarely, hypothyroidism.

• Careful, structured characterisation of the specific discharge pattern forms the essential foundation of clinical assessment and directly informs subsequent diagnostic risk stratification. Establish whether it is unilateral or bilateral, arises from a single duct or multiple ducts, and occurs spontaneously or only with deliberate expression.
• Record its colour and consistency (clear, milky, yellow, green, brown, or blood-stained).
• Associated features warranting specific, heightened clinical attention include any coexisting palpable breast lump, skin changes, or nipple retraction. Each carries relevance to the broader differential diagnosis. Full breast assessment is essential and extends beyond evaluation of the discharge in isolation.
• A relevant medication history (particularly relating to antipsychotic or other dopamine antagonist medication use), together with menstrual and pregnancy history, should be specifically explored where bilateral, milky discharge suggestive of galactorrhoea is the presenting pattern. Also ask about any symptoms suggestive of hyperprolactinaemia or thyroid dysfunction.
• The patient's age is an important, additional consideration informing overall risk assessment. Pathological discharge in an older woman generally warrants a somewhat lower threshold for full evaluation compared with an equivalent presentation in a younger woman. This reflects the generally increasing relevance of malignancy risk with advancing age across breast presentations more broadly.

• Full clinical breast examination, including careful, systematic attempts to identify the specific, causative duct through gentle compression around the areolar margin where a single-duct discharge pattern is suspected, forms an essential initial component of assessment.
• Where the discharge pattern and clinical context are characteristic of physiological discharge, without any concerning associated feature, reassurance without further specific investigation is generally appropriate, following clear explanation of the benign, physiological nature of the finding.
• Where the discharge pattern raises concern for an underlying pathological cause (particularly unilateral, spontaneous, single-duct, blood-stained discharge), full triple assessment is warranted. This incorporates breast imaging (ultrasound, with or without mammography according to age) and, where indicated, further specific investigation including ductography or surgical exploration.
• This follows the specific diagnostic principles addressed under intraductal papilloma and the broader breast malignancy assessment pathway.
• Where bilateral, milky discharge suggestive of galactorrhoea is present, the appropriate, targeted diagnostic approach is serum prolactin measurement, together with thyroid function testing and a full medication review, following the specific principles detailed under hyperprolactinaemia.
• Cytological examination of the discharge fluid itself carries relatively limited diagnostic sensitivity and is not generally relied upon as a primary diagnostic tool. The full, structured triple assessment approach is the essential, more reliable diagnostic pathway for pathological discharge presentations.

• Physiological or clearly benign, reassuring discharge patterns require no specific treatment beyond reassurance and clear explanation of the underlying, benign mechanism, with the patient advised to avoid repeated, deliberate expression of the discharge, which can itself perpetuate or exacerbate the finding.
• Management of pathological, single-duct discharge suspicious for an underlying intraductal papilloma or other relevant structural cause follows the standard principles for the underlying condition, typically comprising surgical excision (microdochectomy) of the affected duct, both providing symptomatic resolution and definitive histological characterisation.
• Management of galactorrhoea is directed at the specific, identified underlying cause, including review and, where clinically feasible, modification of any relevant causative medication, or specific treatment of confirmed hyperprolactinaemia or an underlying thyroid disorder where identified.
• Where discharge is identified in the context of, or leads to identification of, an underlying malignancy, management follows the full principles for breast cancer or, where relevant, ductal carcinoma in situ.
• Full, clear patient communication throughout the assessment process, together with appropriate reassurance once malignancy has been confidently excluded through the structured, risk-appropriate diagnostic approach, underpins full, systematic management of this common presenting complaint spanning a broad spectrum of underlying causes and associated risk.