Types of nipple discharge
Nipple discharge can be classified in different ways:
Nipple discharge could be spontaneous (without any pressure), in which case it is usually noticed by soiling of clothes. Or it could be expresssed, where the discharge comes only on pressure.
Nipple discharge can be from both the breasts, in which case, the cause is some imbalance of hormones in the body. When the discharge is from one breast only, and specifically, from one duct, then the cause usually lies in that breast itself.
Nipple discharge, for purpose of further investigation, is divided into two categories - whether it is blood stained or whether it is some other colour. It is the blood stained nipple discharge which is a cause of concern. Clear nipple discharges are usually not problematic.
Blood stained discharge
The discharge from the nipple is either 'bloody' (meaning that there is obvious blood coming out of the nipple), or is 'blood stained' (meaning that the discharge is thin watery, but reddish tinge of blood is present). Such discharge tends to be from one breast only (meaning, not on both sides) and there are chances that it could be due to an underlying cancer of the breast. It is important to contact a doctor early, if such a discharge is there.
White discharge or 'Milky' discharge
The discharge from the nipple is white, just like milk. It could be thick or thin. White or 'milky' nipple discharge usually tends to be simultaneously from both the breasts. One of the causes of a white discharge is an increase in the levels of the hormone 'prolactin'. This may settle down on its own over a period of a few motnhs, or may need medications if it persists. This medicines are targeted to reduce the levels of prolactin in the body, which will also reduce the discharge.
Clear 'watery' discharge
This is a very common form of discharge. Here, the nipple discharge is very 'clear' or transparent and looks like 'water'. This usually is a benign condition. There could be some irritation of the ducts draining into the nipple (due to minor infection), which causes such a discharge. Watery discharge usually settles down on its own and does not need any further investigations. Only when the discharge persists for an unusually long time and does not settle, then further investigation is warranted.
Other nipple discharges
Apart from the above three types of nipple discharge, there are a few others as well. Benign breast diseases could lead to a greenish or greenish brown discharge. AGain, this could be from both breasts or could be from one side only. Greenish brown discharge are usually not a cause of worry.