Nipple Discharge

Discharge of fluid from one or both nipples

  • Age, genetics, and lifestyle as risk factors depend on the cause

It is normal for women to release milk from their nipples during late pregnancy and while breast-feeding. At any other time, a nipple discharge may be due to hormonal changes in the menstrual cycle or a symptom of a minor disorder. However, because the condition may be a sign of a more serious disorder, such as breast cancer, you should see your doctor if you notice an unusual discharge, if the discharge is bloodstained, or if you are at all concerned.

What are the causes?

The main causes of nipple discharge are hormonal changes, enlargement of the mammary ducts, infection within the breast, or, more rarely, a breast tumour. Fluid discharged from the nipples can vary considerably in colour and consistency, and its appearance is not always a good indication of the cause.

Hormonal changes

Changes in the levels of female sex hormones may produce a discharge, usually from both nipples, just before a period. This type of discharge is usually clear and watery.

A watery, milky discharge in women who are not pregnant or breast-feeding is known as galactorrhoea. This may be a result of overproduction of prolactin, a hormone produced by the pituitary gland. The condition may be due to a noncancerous tumour of the pituitary gland, called a prolactinoma, or may be an effect of a hormonal disorder such as hyperthyroidism. Some drugs, including some antipsychotics, can cause galactorrhoea as a side effect.

Mammary duct enlargement

In this condition, known medically as mammary duct ectasia, one or more milk ducts under the areola become enlarged and may produce a discharge, which may sometimes be bloodstained. The cause is not known, but the condition is more common in older women, particularly those who smoke.

Breast infection

In breast-feeding women, blocked milk ducts may become infected and produce a discharge of pus from the nipples (see Mastitis). In nonbreast-feeding women, smoking may be associated with inflammation of the milk ducts, producing a pus-containing nipple discharge. This is most common in women under 40. Mastitis may also occur for no obvious reason.

Breast tumours

A watery discharge from the nipple may be associated with a cancerous breast tumour. A bloodstained discharge from the nipple may also be a symptom of cancer, although, more commonly, this type of discharge is the result of a noncancerous tumour (called a papilloma) forming within a duct.

What might be done?

Your doctor will carry out a physical examination of your breasts. He or she may take a sample of the discharge to be examined for evidence of infection or cancerous cells. X-rays of the breast (see Mammography) and ultrasound scanning may be performed. A blood sample may be taken to measure hormone levels.

In most cases, a discharge that is caused by mammary duct enlargement does not need treatment. In rare cases your doctor may recommend surgery to remove the affected duct or ducts, which usually stops the discharge. A discharge due to normal hormonal changes is usually harmless and does not require treatment. Galactorrhoea can often be treated successfully using drugs, such as cabergoline (see Pituitary drugs), which reduce the production of prolactin by the pituitary gland. If galactorrhoea is due to a tumour in the pituitary gland, surgery and radiotherapy may be required. A discharge of pus usually clears up after treatment with antibiotics. A bloodstained discharge caused by a noncancerous tumour of a milk duct is normally treated by surgical removal of the duct.

If initial tests reveal that your nipple discharge has been caused by a cancerous growth in the breast, you will be referred for further tests and treatment.

From the 2010 revision of the Complete Home Medical Guide © Dorling Kindersley Limited.

The subjects, conditions and treatments covered in this encyclopaedia are for information only and may not be covered by your insurance product should you make a claim.

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