Nipple discharge is fluid from the nipple, with or without squeezing the breast. The discharge can be milky, clear, green, purulent, bloody, or faintly yellow. The consistency can be thick, thin, sticky, or watery. Milky discharge in a non-pregnant, non-breast feeding women is evaluated differently to other abnormal nipple discharge. Often, the cause can be determined based on symptoms and examination. Blood tests may be done to rule out low thyroid or high prolactin. Other tests may include mammography, breast ultrasound, breast biopsy, or skin biopsy.