Clinical Perspective
In clinical practice, the most common mistake is reassuring a patient because blood in the urine appeared only once. Transient hematuria can indeed be due to an infection or a stone, but resolution of the symptom does not rule out a more serious cause. The correct approach is to confirm the hematuria and evaluate it based on age, smoking history, pain, infection, medications and imaging findings.
Key Takeaways
- Visible blood in the urine should not automatically be attributed to a urinary infection without further evaluation.
- Microscopic hematuria is detected on a urinalysis and is assessed according to the patient’s individual risk.
- Flank pain with blood in the urine often suggests a stone, but does not confirm it.
- In smokers, people over 40, or with persistent hematuria, investigation for malignancy is needed.
- Evaluation usually includes a urinalysis, urine culture, ultrasound or CT urography, and often cystoscopy.
What Is Blood in Urine (Hematuria)?
Hematuria is the presence of red blood cells in the urine. It is classified as gross, when blood is visible to the naked eye, or microscopic, when it is only detected on a urinalysis. The color can range from pink, red, or brown to tea-colored, depending on the amount and origin of the blood.
How Patients Typically Describe It
- red or pink urine
- urine that looks like tea or cola
- blood clots when urinating
- blood at the start or end of urination
- red blood cells found on a urinalysis with no visible color change
Symptoms That Often Occur Together
- burning during urination
- frequent urination
- renal colic
- fever
- blood clots
- inability to urinate
What Are the Most Common Causes
Urinary tract infections
Cystitis, pyelonephritis or prostatitis can cause blood in the urine, usually together with burning, frequent urination, fever or pain.
Urinary stones
A stone in the kidney or ureter can injure the lining and cause hematuria, often with colicky pain.
Prostate conditions
Benign enlargement, inflammation, or, less commonly, prostate cancer can be associated with blood in the urine.
Urinary tract tumors
Bladder, kidney, or upper urinary tract cancer can present with painless hematuria.
When It May Be Harmless — and When It Is Not
Less Concerning
Sometimes red-colored urine is due to certain foods, medications, or intense exercise. This should not be assumed without a urinalysis, especially if the finding persists or recurs.
Needs Attention
Concerning features include painless visible hematuria, blood clots, recurrence, smoking, age over 40, weight loss, flank pain, or fever.
When Immediate Medical Evaluation Is Needed
- blood clots with difficulty urinating
- hematuria with fever or chills
- severe flank or back pain
- hematuria after trauma
- dizziness, weakness, or significant blood loss
How the Diagnosis Is Made and Which Tests May Be Needed
Diagnosis begins by confirming the hematuria on a urinalysis and assessing for infection. The work-up is then tailored to the patient’s risk: ultrasound, CT urography, urine cytology, or cystoscopy may be needed to fully evaluate the urinary tract.
urinalysis with microscopy
urine culture
kidney and bladder ultrasound
CT urography
cystoscopy
kidney function tests
How It Differs From Similar Symptoms
Hematuria must be distinguished from hemoglobinuria, myoglobinuria, and urine discoloration from food or medication. Urine microscopy is decisive, as it shows whether red blood cells are truly present.
What to Expect at Your First Medical Evaluation
At the first evaluation, the urologist will ask when the blood appeared, whether there was pain, whether clots were present, which medications are being taken, and whether there is a history of smoking or stones. Information about whether the blood appears at the start, throughout, or at the end of urination helps localize the likely source.
The information in this article is general and does not replace an individualized medical examination. If your symptoms persist, recur, or are accompanied by red-flag warning signs, please schedule an evaluation with a urologist.
Book an appointmentFrequently Asked Questions
Can hematuria be caused by a urinary infection?
Yes, but it should not be assumed without confirmation. If the culture is negative, if the bleeding persists, or if the patient is male, a smoker, or older, a full urological work-up is needed.
If the blood in the urine stopped, is testing still needed?
Yes, especially if it was visible. Transient hematuria can be the only sign of a stone or a urinary tract tumor.
Is cystoscopy painful?
Flexible cystoscopy is usually performed with local anesthetic gel and is a brief procedure. It may cause mild discomfort but is very useful for examining the bladder.
Can blood thinners explain blood in the urine?
Blood thinners can reveal bleeding, but they do not rule out an underlying condition. Hematuria in a patient on blood thinners still needs evaluation.
When is it an emergency?
It is an emergency when there are clots, inability to urinate, fever, severe pain, or a significant amount of blood.
What is the most important test?
There is no single test for everyone. Urinalysis confirms the finding, while cystoscopy and CT urography are used when the entire urinary tract needs to be examined.
Medical Review
Dr. Marinos Vasilas, Surgical Urologist — Andrologist
This content has been written and reviewed based on established urological guidelines, with the goal of providing practical, safe guidance for the initial assessment of each symptom.
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