Any penile discharge other than urine or semen is considered abnormal. The reasons for penile discharge can vary from infection to retrograde ejaculation to congestive prostatitis. . Presence of constitutional symptoms like fever, itching, burning / pain while urinating are suggestive of infection. However, the absence of these constitutional symptoms does not rule out infection. You mentioned that a sonography has be done. Was sonography suggested by a medical consultant or you chose to take the test on your own? Were any other tests / examination like urine or blood analysis conducted? It is best to have a complete clinical evaluation at the earliest so that a detail history and examination can help arrive at a diagnosis, as infection, if any, can be treated by the use of appropriate treatment.