I am 67 years old and have never smoked. I went to hospital 1 month ago because of chills, nausea, right lower back pain. In the hospital, blood, urine, ultrasonic, etc. Were examined within 2 days. Nothing was found and I was discharged. However, I went to hospital a week ago and was examined by a urologist. In my urine, blood was detected in level +3. Protein was also found (Trace). Urea and creatinine levels were slightly higher. Then, according to my ultrasound scan; 19 � 17 � 13 mm in sizes, a mass was found in the solid structure, from mucous towards lemon in my bladder. Thus the doctor decided to operation. However, I went to hospital today. The results of my urine test (3rd test) today were normal. I have no blood in my urine nor protein. My questions are; 1. What can this mass be? Is it dangerous? 2. What is the reason why my current urine test is clean? What does it mean? Thank you from now. Note: I had a prostate operation a year ago.