Blood in Urine: Causes and When to Worry

What Does Blood in Urine Mean?

Hematuria means that red blood cells are present in the urine. The bleeding can come from different parts of the urinary system, including the kidneys, ureters, bladder, urethra, or, in men, the prostate.

Hematuria is a symptom or laboratory finding rather than a diagnosis. Finding blood tells a clinician that further context may be needed; it does not by itself reveal where the blood came from or why it occurred.

Visible or gross hematuria

Visible hematuria, also called gross hematuria, means you can see a change in urine color caused by blood. The urine may appear pink, red, tea-colored, or brown.

It takes only a small amount of blood to noticeably change urine color, so dramatic-looking urine does not necessarily mean that a large amount of blood has been lost. Gross hematuria is also often painless.

Visible blood should still be medically evaluated because both relatively minor and more important conditions can produce the same appearance.

Microscopic hematuria

Microscopic hematuria means red blood cells are present even though the urine looks normal. Many people have no symptoms and learn about it only after a laboratory urine test.

Current American Urological Association guidance defines microhematuria as at least 3 red blood cells per high-power field (RBC/HPF) on microscopic examination of a properly collected urine specimen.

Microscopic hematuria does not automatically indicate serious disease. The importance of the finding depends on factors such as whether it persists, how many RBCs are present, age, smoking history, previous visible hematuria, urinary symptoms, and other clinical risk factors.

Red urine does not always mean blood

Not every red or orange color change is hematuria. Foods such as beets, certain medications, and food dyes can alter urine color. Menstrual or other genital bleeding can also enter a urine sample and produce a positive result.

When the cause is uncertain, urine testing can help distinguish actual hematuria from a harmless color change or contamination.

What Does Blood on a Urine Test Mean?

A urine test may use terms such as blood, RBCs, red blood cells, erythrocytes, or trace blood. These findings are related, but they are not all interpreted in exactly the same way.

Positive dipstick vs. RBCs on microscopy

A urine dipstick is a useful screening test. However, a positive dipstick result for blood does not by itself confirm microscopic hematuria.

When confirmation is needed, the urine is examined microscopically to determine whether red blood cells are actually present and approximately how many are seen per high-power field.

This distinction matters because a dipstick can sometimes react even when intact red blood cells are not seen under the microscope. For that reason, a laboratory report showing “trace blood” should be interpreted together with microscopic findings and the clinical situation.

What does RBC in urine mean?

RBC stands for red blood cell. Red blood cells detected on urine microscopy are the finding used to identify microscopic hematuria.

The number of RBCs does not identify the cause by itself. A clinician also considers symptoms, whether the result persists on repeat testing, medications, recent exercise or procedures, possible infection, kidney function, and other health information.

What about WBCs and leukocytes?

White blood cells (WBCs), also called leukocytes, are different from red blood cells. Increased WBCs may occur with infection or inflammation, but they do not by themselves explain the presence of RBCs.

If both red and white blood cells are present, the results are interpreted together with symptoms and, when appropriate, urine culture or other testing.

Common Causes of Blood in Urine

Blood can enter the urine for many reasons. Some causes are temporary or readily treatable, while others require additional investigation.

Urinary tract infection

A urinary tract infection (UTI) can inflame urinary tissues and sometimes cause microscopic or visible blood.

Other symptoms may include burning during urination, urinary urgency, frequent urination, lower abdominal discomfort, or cloudy urine.

When hematuria occurs with a UTI, repeat urine testing may sometimes be recommended after the infection has been treated to make sure the blood has resolved.

Kidney or urinary tract stones

Kidney stones can irritate or injure the lining of the urinary tract and cause either microscopic or visible hematuria.

A stone may also cause intense pain in the side, back, lower abdomen, or groin. Nausea, vomiting, urinary urgency, and pain during urination may occur, although symptoms vary according to the stone’s size and location.

Prostate conditions

In men, an enlarged prostate or inflammation involving the prostate can sometimes contribute to blood in the urine.

Other symptoms may include a weak or interrupted urine stream, difficulty starting urination, urinary frequency, urgency, pelvic discomfort, or a feeling that the bladder has not emptied completely.

See our overview of Prostate Health.

Kidney disease

Diseases affecting the kidney’s filtering structures can allow red blood cells to leak into the urine. In some cases, kidney-related hematuria occurs together with protein in the urine, reduced kidney function, swelling, or high blood pressure.

These findings do not occur in every person with kidney disease. When a medical kidney disorder is suspected, additional urine and blood testing and sometimes nephrology evaluation may be appropriate.

Bladder, kidney, and other urinary tract cancers

Hematuria can sometimes be associated with cancer of the bladder, kidney, prostate, or another part of the urinary tract. Blood in the urine does not mean that a person has cancer; many noncancerous conditions can cause exactly the same symptom.

However, unexplained visible blood or persistent microscopic hematuria deserves appropriate evaluation because serious causes cannot be ruled out from symptoms alone. Factors such as age, smoking history, previous gross hematuria, and certain occupational or treatment exposures can affect risk.

Exercise, injury, and urinary procedures

Strenuous exercise can sometimes be followed by temporary blood in the urine. Trauma and recent procedures involving the urinary tract may also cause bleeding.

If hematuria persists, repeatedly returns, or occurs without a clear explanation, it should not simply be assumed to be exercise-related.

Blood-thinning and other medications

Anticoagulant and antiplatelet medications can make bleeding more apparent, and several other medications have also been associated with hematuria.

However, blood in the urine should not automatically be blamed on a blood thinner. Current urologic guidance recommends evaluating confirmed microscopic hematuria in people taking anticoagulant or antiplatelet therapy using the same risk-based approach used for other patients.

What Other Symptoms Can Tell a Clinician

Symptoms occurring with hematuria can help narrow the possibilities, although no symptom combination provides a diagnosis on its own.

These patterns provide context, not a diagnosis. Different conditions can produce very similar urinary symptoms.

Blood Clots in Urine

Visible hematuria can sometimes include blood clots in the urine. Clots may look like dark-red pieces, strings, or larger collections of blood.

Passing clots can be painful. More importantly, a larger clot can obstruct the flow of urine from the bladder.

Blood clots deserve prompt medical attention. Seek urgent care if you cannot urinate, urine flow becomes markedly reduced, bleeding is heavy or rapidly increasing, pain is severe, or you feel weak, dizzy, or seriously unwell.

Blood in Urine Without Pain

Hematuria does not always cause discomfort. A person may have visible blood in the urine without burning, pelvic pain, or flank pain, and microscopic hematuria usually causes no symptoms at all.

The absence of pain does not tell you whether the cause is minor or serious. Unexplained visible blood and persistent microscopic hematuria should still be evaluated appropriately.

For a more detailed discussion of this symptom pattern, see Blood in Urine Without Pain.

How Blood in Urine Is Evaluated

The goal of evaluation is not simply to confirm that blood is present. It is to understand where it may be coming from and whether additional investigation is necessary.

A healthcare professional may ask whether the blood was visible or found on a test, whether it has happened before, whether clots are present, and whether you also have pain, burning, fever, urinary frequency, difficulty urinating, or other symptoms.

Medical history can also matter, including previous UTIs or stones, smoking history, medications, kidney disease, recent procedures, and possible menstrual or genital bleeding.

Urinalysis and microscopy

Urinalysis can screen for blood as well as other abnormalities. If a dipstick is positive for blood, microscopic examination can determine whether red blood cells are actually present.

When an obvious temporary or treatable explanation is identified, repeat testing may sometimes be used after that condition has resolved.

Urine culture and blood tests

A urine culture may be appropriate when symptoms or urinalysis findings suggest infection.

Blood tests may be used when clinicians need information about kidney function, anemia, infection, or another condition relevant to the suspected cause.

Risk-based evaluation of microscopic hematuria

The risk-based approach described below applies to the evaluation of microhematuria in adults. Hematuria in children requires age-appropriate medical evaluation.

Not everyone with microscopic hematuria needs the same tests. Current AUA/SUFU guidance divides adults with confirmed microhematuria into risk groups using factors such as age, sex, smoking history, the number of RBCs found, persistence of hematuria, previous gross hematuria, and additional risk factors for urinary tract cancer.

For people considered at low or negligible risk, repeat urinalysis may be recommended before immediate cystoscopy or imaging. People in higher-risk categories may need additional evaluation.

This risk-based approach helps avoid unnecessary testing while making sure people with more concerning findings receive appropriate investigation.

Imaging

Ultrasound, CT-based imaging, MRI, or another imaging test may be recommended depending on the suspected cause and risk profile. Imaging can help clinicians evaluate the kidneys and other parts of the urinary tract for stones, obstruction, masses, or structural abnormalities.

Cystoscopy

Cystoscopy allows a urologist to examine the inside of the urethra and bladder with a thin viewing instrument. Whether it is needed depends on factors such as the type and persistence of hematuria and the person’s risk profile.

Having blood detected in the urine does not mean that everyone automatically needs both CT imaging and cystoscopy.

What Information Is Helpful at a Medical Visit?

If you are being evaluated for blood in the urine, it can help to note whether the blood was visible or found only on a test, whether clots were present, and whether the episode happened once or has returned.

• When the blood first appeared and whether it has happened before
• Whether you have pain, burning, fever, urgency, or difficulty urinating
• Whether blood clots were present
• Recent UTIs, kidney stones, vigorous exercise, injury, or urinary procedures
• Current medications, especially anticoagulant or antiplatelet drugs
• Smoking history and previous episodes of visible hematuria
• Whether menstruation or other genital bleeding could have affected the urine sample

Bringing this information to a medical visit can help a healthcare professional decide which tests, if any, are appropriate.

When to Seek Medical Care

A useful rule is not to ignore unexplained blood in the urine. Visible hematuria should be discussed with a healthcare professional even if it occurs only once or causes no pain.

Microscopic blood found on a urine test is different: the next step depends on whether microscopy confirms RBCs, whether the finding persists, and the person’s symptoms and risk factors.

Contact a healthcare professional promptly if you have:

• Pink, red, tea-colored, or brown urine that may contain blood
• Hematuria that disappears and then returns
• Persistent or recurrent microscopic blood on urine testing
• Blood together with burning, frequent urination, or urinary urgency
• Blood together with unexplained side, back, pelvic, or abdominal pain
• Blood in the urine while taking anticoagulant or antiplatelet medication

Seek urgent medical care if you have:

• Blood clots with difficulty or inability to urinate
• Heavy or rapidly increasing visible bleeding
• Severe flank, back, abdominal, or pelvic pain
• Fever or chills together with significant urinary symptoms or flank pain
• Persistent vomiting or inability to keep fluids down
• Severe weakness, dizziness, confusion, or a feeling of being seriously unwell

If you believe you may be experiencing a medical emergency, seek emergency medical care.

Common Questions About Blood in Urine

What is the most common cause of blood in urine?

There is no single cause that is most common for every age and situation. UTIs, urinary stones, prostate conditions, exercise, kidney disorders, medications, and other urinary tract conditions can all cause hematuria. The most likely explanation depends on symptoms, age, sex, medical history, and whether the blood is visible or microscopic.

Is microscopic hematuria serious?

Often it is not possible to judge the significance from one result alone. Microscopic hematuria can have temporary or treatable causes, but persistent or unexplained findings sometimes require additional evaluation. Risk is assessed using the laboratory result together with age, smoking history, previous visible hematuria, symptoms, and other factors.

Can blood in urine occur without pain?

Yes. Gross hematuria is often painless, and microscopic hematuria usually causes no symptoms. The absence of pain does not identify the cause, so unexplained visible blood or persistent microscopic hematuria should not be ignored.

What does RBC in urine mean?

RBC means red blood cell. Finding red blood cells under the microscope can confirm microscopic hematuria when the number meets the accepted threshold. The result does not identify the underlying cause on its own.

Can a urine dipstick show blood when microscopy does not show RBCs?

Yes. A dipstick may test positive for blood even when intact red blood cells are not seen microscopically. This is one reason a positive dipstick alone is not used to define microscopic hematuria.

Can dehydration cause blood in urine?

Dehydration makes urine more concentrated, but it should not automatically be assumed to explain confirmed hematuria. Visible blood or repeatedly detected RBCs should be evaluated according to the clinical situation rather than attributed to dehydration alone.

Are the causes different in women and men?

Many causes are the same in women and men, including UTIs, kidney stones, kidney disease, and urinary tract tumors. In men, prostate conditions may also contribute. In women, menstrual or other genital bleeding can sometimes contaminate a urine sample, so clinicians may repeat testing when necessary to confirm that the blood is coming from the urinary tract.

Medical Sources and References

• American Urological Association (AUA) and Society of Urodynamics, Female Pelvic Medicine & Urogenital Reconstruction (SUFU). Microhematuria: AUA/SUFU Guideline (2020, Amended 2025).
• American Urological Association. AUA/SUFU Microhematuria Diagnostic Algorithm, 2025.
• National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). Hematuria (Blood in the Urine).
• National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). Glomerular Disease.
• Mayo Clinic. Blood in urine (hematuria): Symptoms and causes.

Medical Disclaimer

This page provides general educational information and is not a substitute for professional medical advice, diagnosis, or treatment. Blood in the urine can have many possible causes, and information on a website cannot determine the cause for an individual person.

Consult a qualified healthcare professional about visible, persistent, recurrent, or otherwise concerning hematuria. If you believe you may be experiencing a medical emergency, seek emergency medical care.

Learn more about our editorial standards on the Editorial Policy & Medical Disclaimer page.