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Nipple Discharge

by Mary Ann Kosir, MD

Fluid that leaks from one or both nipples is called a nipple discharge. Each breast has several (15 to 20) milk ducts. A discharge can come from one or more of these ducts.

Nipple discharge can occur normally during the last weeks of pregnancy and after childbirth when breast milk is produced. A nipple discharge can also be normal in women who are not pregnant or breastfeeding, especially during the reproductive years. For example, in women, fondling, suckling, irritation from clothing, or sexual arousal can stimulate a nipple discharge, as can stress. However, a nipple discharge in men is always abnormal.

A normal nipple discharge is usually a thin, cloudy, whitish, or almost clear fluid that is not sticky. However, the discharge may be other colors, such as gray, green, yellow, or brown. During pregnancy or breastfeeding, a normal discharge is sometimes slightly bloody. Abnormal discharges vary in appearance depending on the cause. An abnormal discharge may be accompanied by other abnormalities, such as dimpled skin, swelling, redness, crusting, sores, and a retracted nipple. (A nipple is retracted if it pulls inward and does not return to its normal position when it is stimulated.) If a discharge from only one breast occurs on its own (without any stimulation of the nipple), it may be abnormal.

Causes

Several disorders can cause an abnormal discharge. A discharge from one milk duct or from one breast is likely to be caused by a problem with that breast, such as a noncancerous (benign) or cancerous breast tumor. A discharge from both breasts or from several milk ducts in one breast is more likely to be caused by a problem outside the breast, such as a hormonal disorder or use of certain drugs.

Common causes

Usually, the cause is a benign disorder of the milk ducts:

  • A benign tumor in a milk duct (intraductal papilloma)

  • Dilated milk ducts (mammary duct ectasia)

  • Fibrocystic changes, including pain, cysts, and general lumpiness

  • An abscess or infection

Intraductal papilloma is the most common cause. It is also the most common cause of a bloody nipple discharge when there is no lump in the breast.

Less common causes

Certain disorders stimulate the production of breast milk in women who are not pregnant or breastfeeding. In most of these disorders, the level of prolactin (a hormone that stimulates production of breast milk) is elevated. Taking certain drugs can have the same effect.

Cancer causes fewer than 10% of cases.

Evaluation

Warning signs

Nipple discharge is a cause for concern when it

  • Occurs without the nipple's being squeezed or stimulated by other means (when it occurs spontaneously)

  • Occurs in women aged 40 or older

  • Comes from only one breast

  • Is bloody or pink

  • Is accompanied by a lump that can be felt

  • Occurs in a boy or man

When to see a doctor

If a nipple discharge continues for more than one menstrual cycle or if any of the warning signs are present, women should see a doctor. Delay of a week or so is not harmful unless there are signs of infection such as redness, swelling, and/or a discharge of pus. Women with such symptoms should see a doctor within 1 or 2 days.

What the doctor does

Doctors first ask questions about the woman's symptoms and medical history. Doctors then do a physical examination. What they find during the history and physical examination often suggests a cause of the discharge and the tests that may need to be done (see Table below).

To help identify the cause, doctors ask about the discharge and about other symptoms that may suggest possible causes. Women are also asked whether they have had disorders or take drugs that can increase prolactin levels.

Doctors examine the breast, looking for abnormalities, including lumps (see Warning signs). If the discharge does not occur spontaneously, the area around the nipples is gently pressed to try to stimulate a discharge.

Some Causes and Features of Nipple Discharge

Cause

Common Features*

Tests

Benign breast disorders

Intraductal papilloma (a benign tumor in a milk duct)—the most common cause

A bloody or pink discharge from one breast

Usually ultrasonography

Additional tests depending on the results (as for breast lumps—see Breast Lumps : Evaluation)

Mammary duct ectasia (dilated milk ducts)

A bloody, pink, or multicolored (puslike, gray, or milky) discharge from one or both breasts

Same as for intraductal papilloma

Fibrocystic changes (including pain, cysts, and general lumpiness)

A lump, often rubbery and tender, usually developing before menopause

Possibly a history of having breast lumps

Same as for intraductal papilloma

An abscess or infection

Pain, tenderness, redness, warmth, or a combination that begins suddenly in a breast

Often fever

With an abscess, a tender lump and possibly a puslike discharge that smells foul

Physical examination (infection is usually obvious)

If the discharge does not resolve with treatment, evaluation as for intraductal papilloma

Breast cancer

Usually intraductal carcinoma or invasive ductal carcinoma

Possibly a palpable lump, changes in the skin, or enlarged lymph nodes, most often in the armpit

Sometimes a bloody or pink discharge

Same as for intraductal papilloma

Increased levels of prolactin

Various disorders, including the following:

A milky (not bloody) discharge, usually from both breasts

No lumps

Possibly menstrual irregularities or no menstrual periods (amenorrhea)

Blood tests to measure prolactin and thyroid-stimulating hormone levels

A review of drugs being taken

If the prolactin or thyroid-stimulating level is elevated, MRI of the head

  • Hypothyroidism (an underactive thyroid gland)

Intolerance of cold, sluggishness, constipation, or weight gain

  • Disorders of the pituitary gland or hypothalamus (part of the brain)

Possibly hormonal abnormalities, changes in vision, or headaches

  • Chronic kidney or liver disorders

With liver disorders, ascites or jaundice

In people known to have a kidney or liver disorder

Certain drugs including

  • Opioids

  • Oral contraceptives

  • Some drugs used to treat stomach disorders (such as cimetidine, ranitidine, and metoclopramide)

  • Some antidepressants and phenothiazines (drugs used to treat nausea or psychosis), such as prochlorperazine

  • Some antihypertensives (such as atenolol, labetalol, methyldopa, reserpine, and verapamil)

Blood tests to measure prolactin and thyroid-stimulating hormone levels

A review of drugs being taken

If the prolactin or thyroid-stimulating level is elevated, MRI of the head

*Features include symptoms and the results of the doctor's examination. Features mentioned are typical but not always present.

A hormone that stimulates production of breast milk.

MRI = magnetic resonance imaging.

Testing

If doctors suspect that a hormonal disorder is the cause, blood tests are done to measure the levels of prolactin and thyroid-stimulating hormone.

If a pituitary or brain disorder is suspected, magnetic resonance imaging (MRI) or computed tomography (CT) of the head is done.

If the discharge is not obviously bloody, it is analyzed to determine whether it contains small amounts of blood. If blood is present, a sample of the discharge is examined under a microscope (called cytology) to look for cancer cells.

If a lump can be felt, ultrasonography is done. Testing is similar to that for any breast lump (see Testing). Cysts are drained (by aspiration), and the fluid is tested. If cysts remain after aspiration or if lumps are solid, mammography is done, followed by a biopsy.

When there is no lump but cancer is still suspected or when other test results are unclear, mammography is done.

If ultrasonography and mammography do not identify a cause and the discharge occurs spontaneously and comes from one milk duct, doctors usually do an imaging test (such as MRI) after a contrast agent (which helps make images clearer) is injected into the duct. This test can help rule out or identify cancer.

If no lump can be felt and the mammogram is normal, cancer is highly unlikely. Sometimes a specific cause cannot be identified.

Treatment

If a disorder is identified, it is treated. If a noncancerous tumor or disorder is causing a discharge from one breast, the duct that the discharge is coming from may be removed. This procedure requires only a local anesthetic and does not require an overnight stay in the hospital.

Key Points

  • Usually, the cause of nipple discharge is not cancer.

  • If the discharge comes from both breasts or from several milk ducts and is not bloody or pink, the cause is usually a noncancerous hormonal disorder.

  • If the discharge comes from only one breast or one milk duct and is bloody or pink, cancer is possible, especially in women aged 40 or older.

Resources In This Article

Drugs Mentioned In This Article

  • Generic Name
    Select Brand Names
  • COMPRO
  • No US brand name
  • ZANTAC
  • CALAN
  • No brand name
  • TENORMIN
  • REGLAN
  • TAGAMET