Differential diagnosis
Hematuria can be classified according to visibility, anatomical origin, and timing of blood during urination.In terms of the visibility, hematuria can be visible to the naked eye (termed "gross hematuria") and may appear red or brown (sometimes referred to as tea-colored), or it can be microscopic (i.e. not visible to the eye but detected with a microscope or laboratory test). Microscopic hematuria is present when there are three or more red blood cells per high power field. In terms of the anatomical origin, blood or red blood cells can enter and mix with urine at multiple anatomical sites within the urinary system, including the kidney, ureter, urinary bladder, and urethra, and in men, the prostate. Additionally, menstruation in women may cause the appearance of hematuria and may result in a positive urine dipstick test for hematuria. The causes corresponding to these anatomic locations can be divided into glomerular and non-glomerular causes, referring to the involvement of the glomerulus of the kidney. Non-glomerular causes can be further subdivided into upper urinary tract and lower urinary tract causes. In terms of the timing during urination, hematuria can be initial, terminal or total, meaning blood can appear in the urine at the onset, midstream, or later. If it appears soon after the onset of urination, a distal site is suggested. A longer delay suggests a more proximal lesion. In other words, shorter times suggest distal sites while longer times suggest proximal sites. Hematuria that occurs throughout urination suggests that bleeding is occurring above the level of the bladder.
To be in the low risk category, one must satisfy all of the following criteria: Has never smoked tobacco or smoked less than 10 pack-years; is a female less than 50 years old or a male less than 40 years old; has 3-10 red blood cells per high power field; has not had microscopic hematuria before; and has no other risk factors for urothelial cancer. To be in the intermediate risk category, one must satisfy any of the following criteria: Has smoked 10-30 pack-years; is a female 50–59 years old or a male aged 40–59 years old; has 11-25 red blood cells per high power field; or was previously a low-risk patient with persistent microscopic hematuria and has 3-25 red blood cells per high power field. To be in the high risk category, one must satisfy any of the following criteria: Has smoked more than 30 pack-years; is older than 60 years of age; or has above 25 red blood cells per high power field on any urinalysis. For the low risk category, the next step is to either repeat a urinalysis with urine microscopy in 6 months or perform a cystoscopy and renal ultrasound. For the intermediate risk category, the next step is to perform a cystoscopy and renal ultrasound. For the high risk category, the next step is to perform a cystoscopy and CT urogram. If an underlying cause for hematuria is discovered, it should be managed appropriately.