Hematuria is the medical term for blood in your urine. It can be visible to the naked eye, turning urine pink, red, or brown, or it can be completely invisible, detectable only under a microscope during a routine lab test. Either way, it signals that red blood cells are leaking into urine somewhere along the urinary tract, from the kidneys down to the urethra. The causes range from completely harmless to serious, which is why any confirmed case deserves attention.
Visible vs. Microscopic Hematuria
Visible hematuria (sometimes called gross hematuria) is exactly what it sounds like: you can see the color change yourself. Even a tiny amount of blood can turn an entire toilet bowl pink, so the dramatic appearance doesn’t always match the severity of the problem. Any episode of visible blood in urine warrants a thorough evaluation.
Microscopic hematuria is far more common and shows up when a urine sample is examined in a lab. The standard diagnostic threshold is three or more red blood cells per high-power microscopic field. Because dipstick tests can produce false positives (they react to substances other than red blood cells, like muscle protein), a positive dipstick result should be confirmed by looking at the urine under a microscope before any further workup begins.
Common Causes
The most frequent causes of hematuria are infections, kidney or bladder stones, and inflammation. Urinary tract infections happen when bacteria enter the urethra and multiply in the bladder, producing bleeding that tints urine red, pink, or brown. Kidney stones can scrape the lining of the urinary tract as they move, causing both blood in urine and significant pain. Infections or inflammation of the prostate can produce the same symptoms in men, often alongside difficulty urinating or an urgent, persistent need to go.
Less commonly, hematuria points to something more serious. Cancers of the bladder, kidney, or prostate can all cause bleeding into the urinary tract. Blood-clotting disorders, sickle cell disease, and kidney diseases that damage the tiny filtering units (glomeruli) in the kidneys are also possible culprits. When glomeruli are inflamed, a condition called glomerulonephritis, red blood cells squeeze through damaged filters and become misshapen. These oddly shaped cells are a useful clue under the microscope, pointing toward a kidney-based problem rather than one lower in the urinary tract.
When Blood in Urine Isn’t Blood
Not every red or pink toilet bowl means hematuria. Beets, berries, and rhubarb can all give urine a blood-like color without any red blood cells present. Certain medications can do the same. This is sometimes called pseudohematuria, and it’s harmless. A simple urinalysis will confirm whether actual blood cells are present.
Exercise-Induced Hematuria
Strenuous exercise, particularly long-distance running, can cause blood to appear in urine temporarily. This type of hematuria occurs in people with no underlying kidney or urinary tract disease and resolves on its own with rest. The exact mechanism isn’t fully understood, but repeated impact on the bladder and increased blood flow to the kidneys during intense activity both play a role. If blood in your urine doesn’t clear up after a couple of days of rest, something else is likely going on.
Why Painless Hematuria Needs Attention
Hematuria that comes with burning, urgency, or flank pain usually has an obvious explanation like an infection or a stone. Painless hematuria, especially visible painless hematuria, is the pattern that raises more concern because it’s the hallmark of urinary tract cancers. A large systematic review of nearly 230,000 patients found that among those with visible hematuria, 17% had bladder cancer and 2% had kidney cancer. For microscopic hematuria, those rates were lower but not negligible: about 3.3% for bladder cancer and 0.6% for kidney cancer. Men and people with a smoking history had higher rates of malignancy in both groups.
This doesn’t mean that painless hematuria usually equals cancer. The majority of cases still trace back to benign causes. But the absence of pain is not reassuring in the way many people assume, and it’s the main reason guidelines call for a structured evaluation.
How Hematuria Is Evaluated
The workup starts with a urinalysis. A dipstick test provides a quick screening result, but it’s not definitive on its own. Microscopic examination of the urine sediment confirms whether red blood cells are truly present and can reveal additional clues, like misshapen red blood cells suggesting kidney disease or cell clusters (casts) pointing to specific conditions.
After confirmation, current guidelines from the American Urological Association sort patients into risk categories based on factors like age, sex, smoking history, and how much blood is present. The recommended next steps differ by risk level:
- Low risk: A repeat urinalysis within six months rather than immediate imaging or procedures. If the blood has cleared, no further workup is needed.
- Intermediate risk: An ultrasound of the kidneys and a cystoscopy, which is a procedure where a thin camera is passed through the urethra to visually inspect the bladder lining.
- High risk: Cystoscopy plus advanced imaging of the upper urinary tract, typically a CT urogram. This type of scan captures detailed cross-sectional images and is more sensitive than ultrasound for detecting small tumors and stones that don’t cause blockages.
Ultrasound plays a particularly important role for children and pregnant women, where avoiding radiation exposure is a priority. When ultrasound results are normal but the source of bleeding remains unclear, CT scanning is the next step because it picks up lesions that ultrasound tends to miss.
What to Expect During a Cystoscopy
Cystoscopy sounds intimidating, but it’s typically a quick outpatient procedure. A thin, flexible scope is inserted through the urethra, and a camera at the tip lets the urologist examine the bladder wall directly. It usually takes about five minutes. You may feel pressure or a brief burning sensation, and there can be mild discomfort urinating for a day or two afterward. For most people, the anticipation is worse than the procedure itself.
Visible Blood Clots in Urine
Passing blood clots is a more alarming version of visible hematuria and can indicate heavier bleeding from the bladder, kidney, or prostate. Small clots that pass once and don’t recur may not signal an emergency, but larger clots can block the flow of urine entirely, causing sudden pain and an inability to urinate. If you’re unable to urinate, experiencing severe pain, or passing large or frequent clots, that situation requires urgent medical attention. An enlarged prostate is one of the more common causes of clot-forming hematuria in older men, though tumors and severe infections can produce the same picture.