Blood in the Urine

Visible or microscopic blood in the urine always deserves a full evaluation — here's what that involves and why it matters.

Two kinds of blood in the urine

Gross hematuria is blood you can see — urine that looks pink, red, or cola-colored. Microscopic hematuria is blood found only under the microscope, usually discovered on a routine urinalysis done for some other reason.

It takes remarkably little blood to change the color of urine, so visible blood is not necessarily a sign of heavy bleeding. But it is a sign that should never be ignored, even if it happens once and then stops.

Why it must be evaluated

Causes range from entirely benign to serious. Common explanations include urinary infection, kidney or bladder stones, an enlarged prostate, vigorous exercise, and recent instrumentation. Kidney disease can also cause it.

The reason we take it seriously is that blood in the urine may be the only early sign of bladder or kidney cancer, and painless visible blood carries the highest concern. These cancers are very treatable when caught early. The evaluation exists to find that small group of people while the finding is still early — and to reassure everyone else.

Blood that stops on its own does not mean the cause has resolved. Bleeding from a tumor is characteristically intermittent. A single episode still warrants a workup.

What the evaluation involves

A complete evaluation has three parts. First, a urinalysis and often a culture, to confirm the blood and rule out infection. Second, imaging — usually a CT urogram, which shows the kidneys and the entire collecting system in detail. Third, cystoscopy, a brief office procedure using a small flexible scope to look directly at the bladder lining, since bladder tumors are not reliably seen on any scan.

Both parts matter. Imaging covers the upper tract; cystoscopy covers the bladder. One does not substitute for the other.

Higher-risk factors

The intensity of evaluation is adjusted for risk. Factors that raise concern include being over 60, a history of smoking — the single largest risk factor for bladder cancer — occupational exposure to dyes, rubber, or industrial chemicals, prior pelvic radiation, certain chemotherapy drugs, and a history of chronic catheter use.

If you smoke, stopping is the most valuable thing you can do for your urinary tract, and the benefit begins to accrue quickly.