Hematuria is a condition where red blood cells are present in the urine. There are two types: ‘visible microscopic’ and ‘visible gross’ hematuria. Microscopic hematuria refers to an incidental finding, usually discovered in a urine test conducted as part of a routine medical examination. Gross hematuria, on the other hand, will probably prompt you to see the doctor because of its visibility. Hematuria can originate from any area of the urinary tract, including the bladder, kidneys, ureters, urethra and prostate. It is believed that hematuria occurs in anything from 2.5% to 21% of the population. Often, no specific cause can be identified, but it could be an indication of infection, stone disease or urinary tract cancer. Risk factors for significant underlying disease include radiation, smoking, overuse of certain pain medicines and exposure to some chemicals.
What are the common causes of hematuria?
Having blood in the urine is not necessarily a sign of significant disease. Studies have shown that between nine and 18 percent of normal individuals have hematuria to some extent. However, it could be a sign of a serious condition that needs medical treatment. Below is a list of common causes of hematuria:
- Bladder/kidney/ureteral/urethral/prostate cancer
- Urinary tract infection
- Urinary stone disease
- Kidney infection (pyelonephritis)
- Benign prostatic hypertrophy (enlarged prostate)
- Prostatitis (prostate infection)
- Renal (kidney) disease
- Radiation or chemical-induced cystitis (bladder irritation)
- Urinary tract injury
- Exercise hematuria
How is hematuria diagnosed?
While gross visible hematuria often prompts patients to seek medical attention; less obvious microscopic hematuria can be just as serious. It often has no symptoms and is detected on a urine dipstick test. If the dipstick test is positive for blood, the proportion of red blood cells is often determined by examining the urine under a microscope. If a microscopic examination finds three or more red blood cells per high power field on two of three specimens, further evaluation to identify a cause is recommended.
If you have hematuria, the urologist will examine your medical history and give you a physical examination. He may order laboratory tests, which include a urinalysis and examination of urinary sediment under a microscope. If you have white blood cells in your urine, a urine culture should be performed as well. A urinary cytology is also undertaken to check for abnormal cells. A blood test will be done to measure serum creatinine (this gives an indication of kidney function). You will need to undergo further examination to check for the possibility kidney disease if you are found to have significant protein in your urine, abnormally shaped red blood cells, or elevated creatinine levels.
A complete urologic evaluation of hematuria can also include ultrasonic or a computerized tomography (CT) scan of the kidneys and ureters to look for the presence of ureter tumors, kidney masses, or urinary stones.
Recently, urologists have been using CT urography, which lets them examine the kidneys and ureters with one X-ray test. If patients have elevated creatinine levels or are allergic to X-ray dye, magnetic resonance imaging (MRI) or retrograde pyelography will be used to examine the upper urinary tract. In retrograde pyelography, a dye is injected up the ureters from the bladder, and then images are taken.
The main limitation of these imaging studies is the inability to evaluate the bladder; therefore, a cystoscopic evaluation is required. This is usually performed in the office under local anesthesia with a flexible cystoscope. After applying a topical analgesic to the urethra, the urologist inserts an instrument called a cystoscope through the urethra and into the bladder. Looking through the cystoscope the doctor can examine the inner lining of the bladder, prostate and urethra for abnormalities.
In about 8% to 10% of cases, no cause for hematuria is found, and some researchers believe this figure may be even higher. Unfortunately, studies show that urologic malignancy is subsequently discovered in 1% to 3% of patients who had negative work-ups. This is why we strongly recommend some form of follow-up. Consideration should be given to repeating the urinalysis and urine cytology at six, 12, 24 and 36 months. Immediate re-evaluation with possible cystoscopy and repeat imaging can be taken in the case of gross hematuria, abnormal urinary cytology or annoying symptoms such as pain on urination or increased frequency of urination. However, if these symptoms don’t occur within three years, no further urologic testing is needed.