Nipple discharge is a typical part of how the breast works during pregnancy or breast-feeding. It also can be linked to menstrual hormone changes and common changes in breast tissue, called fibrocystic breast. The milky discharge after breast-feeding most often affects both breasts. It can continue for up to one year or more after giving birth or stopping nursing.

A papilloma is a noncancerous, also called benign, tumor in a milk duct. A papilloma can be linked to bloody discharge. The discharge linked with a papilloma often happens spontaneously and involves a single duct.

The bloody discharge may clear up on its own. But your healthcare professional is likely to want a diagnostic mammogram and a breast ultrasound to see what's causing the discharge.

You also may need a biopsy to confirm that it's a papilloma or to rule out a cancer. If the biopsy shows a papilloma, a member of your healthcare team will refer you to a surgeon to talk about treatment options.

Often, a harmless condition causes nipple discharge. However, the discharge might mean breast cancer, especially if:

• You have a lump in your breast.
• The discharge comes from only one breast.
• The discharge is bloody or clear.
• The discharge happens on its own and is ongoing.
• You can see that the discharge is coming from a single duct.

Possible causes of nipple discharge include:

1. Abscess.
2. Birth control pills.
3. Breast cancer
4. Breast infection.
5. Ductal carcinoma in situ (DCIS)
6. Endocrine conditions.
7. Fibrocystic breasts
8. Galactorrhea
9. Hypothyroidism (underactive thyroid)
10. Injury or trauma to the breast.
11. Intraductal papilloma.
12. Mammary duct ectasia
13. Medicines.
14. Menstrual cycle hormone changes.
15. Paget's disease of the breast
16. Periductal mastitis.
17. Pregnancy and breast-feeding.
18. Prolactinoma
19. Too much handling of the breast or pressure on the breast.