The breast glandular tissue is made of lobules and ducts. The major ducts end at the nipple thus any secretions made inside the breast lobules or ducts will come out as discharge from the nipple.
Breast glandular cells are designed to produce secretions (fat / protein) in a similar way that sweat glands produce sweat. This is because the breasts start off as modified sweat glands during development.
However, despite this we do not see continuous discharge from the nipples. The reason is that these same cells that produce secretions reabsorb them back (take them back up inside the cells).
Occasionally, this fails to happen resulting in what is called physiological discharge from the nipples. This may be clear, cream, yellow, green or brown coloured and comes from multiple points on the nipple (multiple ducts). It is often bilateral (in both breasts) but may be more on one side.
It happens less than twice a week (as long as you do not express the discharge yourself). Expressing the discharge can increase it.
Dilated ducts under the nipple (duct ectasia) may also result in excessive discharge similar in appearance to physiological discharge.
You should see your local doctor if you develop any new breast symptom including nipple discharge. This is especially important if the discharge is blood-stained and / or is coming from a single point on the nipple.
Excessive discharge from both breasts may also be the result of over-production of hormones such as prolactin. This can be investigated by your doctor with a simple blood test.
Breast cancer is not a common cause of nipple discharge but should be excluded especially in the setting of blood-stained nipple discharge.
Physiological discharge requires no treatment unless it is a nuisance.
Otherwise, treatment depends on the cause of the discharge:
- Breast cancer is ruled out first by examination, breast imaging and sometimes analysis of the discharge.
- Over-production of hormones is usually treated by treating the cause (such as a so-called pituitary adenoma).
- Other causes of single duct discharge may be treated by surgically excising the duct (microdochectomy).
- Multi-duct discharge (such as that from duct ectasia) can also be treated by surgically excising all of the ducts from under the nipple (total duct excision).