What you need to know first
Nipple discharge — fluid coming from the nipple — can be alarming, but many forms are benign and even normal. What matters for assessment is the pattern of the discharge, not just its presence: where it comes from, what it looks like, and whether it appears on its own or only when the nipple is squeezed.
The key distinction a specialist makes is between discharge that is likely to be benign (and needs reassurance, perhaps a scan) and discharge that warrants a fuller investigation.
When to see a specialist
See a specialist if the discharge is:
- Spontaneous — it appears on its own, without squeezing, and stains clothing or is noticed without any prompting
- From one breast only — or from a single duct on the nipple
- Bloodstained — red, pink, brown, or black
- Clear and watery, particularly if spontaneous and persistent
- Accompanied by a lump, skin change, nipple inversion, or pain
- New and persistent in a woman past the menopause
Discharge that appears only when the nipple is squeezed, from both breasts, from multiple ducts, or that is milky is much more often benign — but a specialist assessment is still reasonable if it is recurrent, is new for you, or is causing concern.
If you are pregnant, breastfeeding, or have recently finished breastfeeding, clear or milky discharge is usually a normal physiological finding and does not necessarily need assessment. Bloody discharge in pregnancy can also have benign causes (including the normal vascular changes of pregnancy), but it should still be reviewed by a specialist to rule out other causes.
What nipple discharge might be
The commonest causes, grouped by pattern:
- Physiological (benign and common). Discharge that only appears when the nipple is squeezed, is from both breasts or multiple ducts, and is clear, milky, yellow, or green. Related to normal hormonal and ductal changes. Does not usually need treatment.
- Intraductal papilloma. A small, non-cancerous growth inside a milk duct. This is the commonest cause of spontaneous, single-duct, bloodstained discharge, and it is benign — but it needs to be identified and, in many cases, removed.
- Duct ectasia. Widening and shortening of the ducts behind the nipple, typically seen around and after the menopause. Can cause discharge that is often thick and green, grey, or brown, and may be accompanied by nipple inversion or tenderness.
- Infection. Mastitis or an abscess can produce pus-like discharge, typically with redness, warmth, and pain — more common in breastfeeding but can occur at any age.
- Galactorrhoea. Milky discharge not related to pregnancy or breastfeeding, often from both breasts. Causes include hormonal (a raised prolactin level, sometimes from a pituitary prolactinoma), medication, and, less often, thyroid disease.
- Breast cancer. An uncommon but important cause of spontaneous, single-duct, bloodstained or clear discharge, particularly in older women. Specialist assessment is designed to rule this in or out.
The specific likelihoods of benign vs. malignant causes depend heavily on the pattern and on the patient’s age; for single-duct bloodstained discharge, the commonest cause is an intraductal papilloma, but breast cancer is the reason every case of that pattern gets fully assessed.
How nipple discharge is assessed
Nipple discharge is assessed using a tailored version of triple assessment:
- Clinical examination. Dr Tsang-Wright examines both breasts and nipples, tries to identify the specific duct the discharge comes from if possible, and looks for any lumps, skin changes, or nipple inversion.
- Imaging. A mammogram (in women aged 40 and over) and an ultrasound are the usual first imaging tests. Imaging focused on the area behind the nipple can identify ductal dilatation, small masses, or papillomas.
- Cytology (occasionally). A sample of the discharge itself can sometimes be sent for microscopic examination, though this is less commonly relied on as a stand-alone test because it can miss significant findings.
- MRI (in selected cases). For persistent single-duct bloodstained discharge where ultrasound and mammogram are reassuring, MRI may be arranged.
- Surgical assessment (in selected cases). Where a specific duct is implicated but imaging is inconclusive, a small operation called a microdochectomy (removal of a single duct) or a total duct excision (removal of all ducts) may be recommended to obtain a tissue diagnosis.
Most patients with discharge that is reassuring on history, examination, and imaging do not need a biopsy or surgery.
What happens after the assessment
At the end of the visit you will typically be in one of these positions:
- Reassurance — the pattern is benign (physiological or clearly hormonal), imaging is normal, and no further action is needed.
- A benign diagnosis with a plan — for example an intraductal papilloma on ultrasound, where removal is offered, or galactorrhoea where hormonal tests and onward referral to endocrinology are arranged.
- Further investigation — MRI or a planned microdochectomy or total duct excision.
- A suspicious finding — requiring biopsy or onward investigation as part of a multidisciplinary team plan.
A letter to your GP is sent after every appointment with your permission.