Testing If endocrine causes are suspected, the following are measured: Prolactin level Thyroid-stimulating hormone (TSH) level If discharge is guaiac-positive, the following is done: Cytology If there is a palpable breast mass, evaluation may include Ultrasonography, cyst aspiration, or mammography If there is no mass but cancer is otherwise suspected or if other tests are indeterminate, the following is done: Mammography If results of imaging or cytology (of cyst aspirate) are abnormal, image-guided biopsy is done.