Blood in the urine

What is visible haematuria?

Visible haematuria means blood can be seen in the urine. The urine may look:

• pink;
• red;
• tea-coloured;
• cola-coloured;
• or contain obvious blood or clots.

The colour does not reliably tell you where the bleeding came from.

What can cause blood in the urine?

Possible causes include:

• urinary infection;
• kidney or ureteric stones;
• benign prostate bleeding;
• inflammation;
• trauma or instrumentation;
• kidney disease;
• bladder cancer;
• kidney cancer;
• cancer of the ureter or renal pelvis;
• other less common urinary conditions.

A blood thinner may make bleeding easier to notice, but it does not automatically explain why bleeding has occurred from the urinary tract.

How often does visible haematuria turn out to be cancer?

This is where the evidence is particularly useful.

A 2022 systematic review included 44 studies and 229,701 people investigated for haematuria.¹ Among patients with visible haematuria, the pooled incidence was approximately:

• 17% for bladder cancer (95% CI 14–20%);
• 2% for renal cell carcinoma (95% CI 1–2%);
• 0.75% for upper-tract urothelial cancer (95% CI 0.4–1.2%).¹

These figures should not be read as an individual's personal probability. They come from people who entered haematuria investigation pathways, and risk varies with age, smoking history, sex and other factors.^{1, 3}

But they explain why visible haematuria is treated differently from many everyday urinary symptoms.

Does one episode really matter?

Yes, an otherwise unexplained episode should be discussed with a clinician even if the urine becomes clear again.

Bleeding from the urinary tract can be intermittent. The absence of blood the next day does not necessarily mean the cause has disappeared.

That does not mean everyone needs identical testing. It means the episode deserves risk-based assessment rather than being dismissed solely because it stopped.

Does painless blood matter more than painful blood?

Painless visible haematuria is classically associated with bladder cancer, which is why it attracts particular attention.

But pain does not make bleeding automatically benign. Stones and infection often cause pain, yet a clinician still needs to decide whether that explanation fully accounts for the episode.

Similarly, visible haematuria accompanied by burning may be due to infection, but persistent or recurrent bleeding after treatment may need further assessment.

What factors make cancer more likely?

The international IDENTIFY study involved 10,282 patients referred with haematuria across 110 hospitals in 26 countries.³

Factors associated with a higher risk of urinary-tract cancer included:

• visible rather than non-visible haematuria;
• increasing age;
• smoking history;
• male sex;
• family history.³

The model discriminated reasonably well between higher- and lower-risk patients, supporting the principle of risk-stratified investigation.³

However, risk stratification is not the same as self-exclusion. A person should not decide that visible blood is harmless simply because they are younger or have never smoked.

What does the NHS pathway actually say?

This is the most useful thing a British reader can take from this page.

NICE recommends an urgent suspected-cancer referral — the two-week-wait pathway — for anyone aged 45 or over with unexplained visible haematuria, either without a urinary tract infection or persisting after a urinary infection has been treated. Men aged 60 and over with non-visible haematuria plus raised white cells on a blood test or pain on passing urine also meet the criterion.

If you are in that group and have been told to wait and see, that is worth questioning. Privately, the same assessment can usually be arranged within days rather than weeks.

What happens at a haematuria assessment?

The aim is to examine both the lower urinary tract—particularly the bladder—and the upper urinary tract, meaning the kidneys and ureters.

Depending on the situation, evaluation may include:

• urine testing;
• blood tests;
• imaging such as ultrasound or CT;
• cystoscopy;
• further tests if an abnormality is found.

The exact pathway varies according to age, kidney function, risk factors and local practice.

What is cystoscopy?

Cystoscopy means looking inside the urethra and bladder with a small camera.

For most haematuria investigations, a flexible cystoscopy is used. A thin flexible telescope is passed through the urethra after local anaesthetic gel is applied.

The reason for the test is important: scans can identify many abnormalities, but direct visual inspection remains the standard way to assess the bladder lining for lesions that may otherwise be difficult to characterise.

How accurate is cystoscopy?

A 2023 systematic review from the European Association of Urology Guidelines Office examined cystoscopy for detecting bladder cancer in adults with haematuria.²

Across the available studies, reported cystoscopy sensitivity ranged from 87% to 100%, while negative predictive values ranged from 98% to 100% in the comparisons analysed.²

Those numbers are encouraging but should not be over-interpreted. The review included only nine studies and found substantial variation in methods and reported performance.² The authors concluded that cystoscopy remains the standard test, but also that its diagnostic accuracy in the haematuria setting has not been studied as extensively as might be assumed.²

Will I definitely need a CT scan?

Not necessarily.

Upper-tract imaging may involve ultrasound or CT urography depending on individual risk, kidney function and local protocols.

CT provides detailed imaging but involves radiation and contrast exposure, so risk-based pathways increasingly try to match the test to the patient's probability of disease.

What if I am taking aspirin, warfarin, apixaban or another blood thinner?

Anticoagulant or antiplatelet medication can increase the amount of bleeding from an existing lesion. That means medication may influence how visible the haematuria becomes without necessarily explaining where it came from.

A medication review is therefore part of assessment, but visible haematuria should not automatically be attributed to blood-thinning treatment without considering the urinary tract.

What if the tests are normal?

That is a common and clinically useful outcome.

A normal cystoscopy and appropriate upper-tract assessment may provide substantial reassurance. Sometimes a benign explanation is identified. Sometimes no single cause is found.

Future follow-up depends on risk factors, whether the bleeding recurs and what the initial tests showed.

What symptoms need urgent attention?

Seek prompt or urgent medical care if:

• you are passing large clots;
• you cannot pass urine;
• bleeding is heavy or persistent;
• you feel faint or unwell;
• haematuria occurs with fever or rigors;
• there is severe flank or abdominal pain.

Clot retention—where clots block the bladder outlet—is a urological emergency.

How strong is the evidence?

The cancer-risk figures come from a large systematic review of 229,701 participants, giving a useful pooled estimate for investigated populations.¹

Cystoscopy accuracy is supported by systematic review, although the authors explicitly highlight limited and heterogeneous direct diagnostic-accuracy evidence.²

Risk-factor data from IDENTIFY come from a large prospective international observational cohort.³ This is strong for prediction and association, but it does not prove causation.

Bottom line

Visible blood in the urine is not synonymous with cancer, but neither is it something to normalise.

The best available evidence shows that bladder cancer is found often enough in investigated visible-haematuria populations to justify a structured assessment.¹ Cystoscopy remains the standard test for looking directly at the bladder, while imaging evaluates the kidneys and ureters.²

The right response is neither panic nor delay: get the bleeding properly explained.

This is the one symptom on which I will not be relaxed with you. Blood in the urine that has no obvious explanation should be looked into, even if it happened once and even if it has stopped. Most of the time I find something benign and say so with relief. The reason to look is the minority of times I do not.