Related to smell of urine Before urination

Patient: When there is urge to urinate , smell of urine comes , when I release the urine , smell goes , why it happens as there is no leakage

Symptoms: Blood test ok every time , urine test and culture ok every time , no prostate problem as per test , even if volume of urine is very less in bladder , still there is urge to urinate and the smell will come , once I release this urine , smell goes