The evaluation of microscopic hematuria is one of the most common reasons a patient is sent to see a urologist. The big three things we look for are kidney tumors, bladder tumors or stones. The most common evaluation is a non contrasted Ct scan and cystoscopy (looking into the bladder with a scope). Benign reasons for blood in the urine include irritation of the urethra in a female and the vascular lining of the prostate through which urine passes. Even the evaluation is usually negative, because blood in the urine can represent an early sign of malignancy, it is usually evaluated to assure there is no asymptomatic underlying cause.
In the picture above even though the urine appears clear there can still be significant microscopic blood in the specimen that the patient cannot see and also causing no symptoms.