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Blood in the Urine (Haematuria): Causes and Diagnostic Tests

By Mr Neil Haldar, Consultant Urological Surgeon — Buckinghamshire and the Thames Valley

Blood in the urine is called haematuria. It may be clearly visible, making the urine appear pink, red or brown, or it may be found only when a urine sample is tested.

Haematuria does not necessarily mean cancer. Urinary infection, kidney stones, an enlarged prostate and non-cancerous kidney conditions are all common causes. Nevertheless, blood in the urine should not be ignored because it can occasionally be the first sign of bladder cancer, kidney cancer or another important urinary condition.

The appropriate investigations depend on:

• whether the blood is visible or detected only on testing;
• your age;
• whether you have pain or urinary symptoms;
• smoking and other cancer risk factors;
• the presence of infection;
• kidney function and protein in the urine;
• previous urological conditions or treatment.

Most people referred through a suspected bladder-cancer pathway are not ultimately found to have bladder cancer. The purpose of investigation is to identify the minority who have an important underlying condition while avoiding unnecessary invasive tests in people whose risk is very low.

Seek urgent medical help if you are unable to pass urine, are passing large clots, are bleeding heavily, feel faint or unwell, or have blood in the urine accompanied by severe pain or fever.

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What is haematuria?

Haematuria is the medical term for blood in the urine. It is a symptom rather than a diagnosis: the blood may originate from almost anywhere within the urinary system, including the kidneys, ureters, bladder, prostate or urethra.

There are two principal types.

Visible haematuria

Visible haematuria means that blood can be seen with the naked eye. The urine may look:

• pale pink;
• bright red;
• dark red;
• brown or “cola-coloured”;
• mixed with small or large blood clots.

Even a relatively small quantity of blood can produce a dramatic change in urine colour. The intensity of the colour does not reliably indicate how serious the cause is.

Visible haematuria was previously called macroscopic or gross haematuria.

Non-visible haematuria

Non-visible haematuria means that blood is not apparent when looking at the urine but is detected by a urine dipstick test.

It may be:

• symptomatic, when accompanied by burning, frequency, urgency, discomfort or other urinary symptoms; or
• asymptomatic, when found incidentally during a health check, insurance medical or investigation for another condition.

NICE recommends further assessment of a urine dipstick result of 1+ blood or more. Routine microscopy is not required simply to confirm that a positive dipstick contains blood. When it is necessary to distinguish persistent non-visible haematuria from a temporary finding, two positive results from three dipstick tests are generally used as confirmation.

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Does the colour or timing of the blood identify the cause?

The appearance of the urine may provide useful clues, but it rarely establishes the diagnosis by itself.

Bright red urine is more often associated with bleeding from the lower urinary tract, while dark or cola-coloured urine can occur with bleeding originating in the filtering units of the kidneys. However, there is considerable overlap.

The timing of the bleeding during urination can also provide a clue:

• blood mainly at the beginning of the stream may suggest a urethral source;
• blood mainly at the end may point towards the bladder neck or prostate;
• blood throughout the stream can arise from the bladder or upper urinary tract.

Blood clots generally suggest bleeding from somewhere within the urological tract rather than from the microscopic filtering units of the kidney. Long, thin clots may occasionally have formed within a ureter.

These patterns are helpful when taking a history, but none is sufficiently reliable to replace formal investigation.

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What causes blood in the urine?

There are many possible causes of haematuria. Some are temporary and harmless; others require prompt diagnosis.

1. Urinary tract infection

A urinary tract infection is one of the most frequent causes of blood in the urine.

Typical associated symptoms include:

• burning or pain when passing urine;
• needing to urinate more frequently;
• urgency;
• lower abdominal discomfort;
• cloudy or offensive-smelling urine;
• fever or feeling unwell.

Blood associated with infection should usually resolve after successful treatment. If visible haematuria persists or returns after the infection has been treated, further urological investigation is important.

Repeatedly attributing blood in the urine to infection without confirming that it has cleared can delay the diagnosis of another underlying condition.

Women are particularly vulnerable to this problem because haematuria may be repeatedly treated as cystitis before a urological assessment is considered.

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2. Kidney and ureteric stones

Stones in the kidney or ureter commonly cause visible or non-visible haematuria.

A stone passing down the ureter may produce:

• severe pain in the side or back;
• pain radiating towards the groin;
• nausea or vomiting;
• urinary frequency or urgency;
• blood in the urine.

Some kidney stones produce little or no pain and are discovered only during investigation of haematuria.

Finding a stone does not always mean that no other investigation is necessary. In an older patient, smoker or someone with unexplained visible bleeding, a stone should not automatically be accepted as the complete explanation without considering the rest of the urinary tract.

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3. Benign enlargement of the prostate

The prostate commonly enlarges as men grow older. An enlarged prostate can develop an increased network of delicate blood vessels that may bleed into the urine.

Prostatic bleeding may occur with symptoms such as:

• a slow urinary stream;
• hesitancy;
• difficulty starting;
• needing to pass urine frequently;
• getting up at night;
• a feeling that the bladder has not emptied;
• intermittent urinary retention.

Benign prostatic enlargement is a common explanation for haematuria in men, but it should generally be regarded as a diagnosis of exclusion. The bladder and upper urinary tract may still need assessment, particularly when the bleeding is visible or recurrent.

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4. Bladder cancer

Painless visible haematuria is the best-known presenting symptom of bladder cancer.

The bleeding may:

• occur only once;
• disappear for weeks or months;
• be painless;
• be mistaken for a urinary infection;
• occur while taking anticoagulant medication.

The fact that the bleeding stops does not prove that the underlying cause has resolved.

Bladder cancer becomes more common with increasing age. Smoking is its most important modifiable risk factor. Additional risk factors include certain historic occupational chemical exposures, previous pelvic radiotherapy, previous treatment with cyclophosphamide and a personal history of urothelial cancer.

Most people investigated for haematuria do not have bladder cancer, but the possibility cannot be reliably assessed from symptoms alone. Current pathways therefore combine age, symptoms, smoking history and other risk factors to determine who needs cystoscopy and imaging.

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5. Kidney cancer

Kidney cancer is increasingly found incidentally during scans undertaken for unrelated reasons. It may nevertheless present with blood in the urine.

Possible associated features include:

• discomfort or a persistent ache in the flank;
• unexplained weight loss;
• tiredness;
• anaemia;
• a mass or fullness in the abdomen;
• fever without an obvious infection.

Many people with an early kidney tumour have no symptoms other than haematuria. Imaging of the kidneys is therefore an important part of the investigation in appropriately selected patients.

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6. Upper urinary tract urothelial cancer

Urothelial cancer can develop not only within the bladder but also in the lining of the renal pelvis or ureter. This is known as upper tract urothelial carcinoma.

It is much less common than bladder cancer but can also cause visible or non-visible haematuria.

Some patients experience flank discomfort or pain caused by a clot temporarily obstructing the ureter. Others have no pain at all.

CT urography is particularly useful when upper-tract urothelial disease is suspected because it examines the kidneys, renal collecting systems and ureters in detail.

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7. Kidney and glomerular disease

Not all urinary bleeding comes from a urological structure such as the bladder or prostate. It may originate within the microscopic filters of the kidney, known as the glomeruli.

Features suggesting an intrinsic kidney cause include:

• protein in the urine;
• impaired or declining kidney function;
• high blood pressure;
• swelling of the legs or around the eyes;
• cola-coloured urine;
• blood appearing during or soon after an infection;
• a family history of kidney disease.

Possible causes include:

• IgA nephropathy;
• thin basement membrane disease;
• Alport syndrome;
• glomerulonephritis;
• lupus affecting the kidneys;
• vasculitis;
• interstitial nephritis.

Patients can occasionally have both urological cancer risk factors and evidence of kidney disease. Urological and nephrological investigation may therefore need to take place in parallel rather than one replacing the other.

NICE recommends specialist kidney assessment in circumstances that include significant proteinuria accompanied by haematuria, rapidly declining kidney function, difficult-to-control hypertension and suspected inherited or rare renal disease.

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8. Prostatitis and inflammation

Inflammation or infection of the prostate can cause haematuria, pelvic discomfort and urinary symptoms.

Possible symptoms include:

• pain between the scrotum and anus;
• painful urination;
• urinary frequency;
• discomfort during or after ejaculation;
• fever or flu-like symptoms in acute infection;
• difficulty passing urine.

Inflammation of the urethra, bladder or kidneys can also cause urinary bleeding.

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9. Blood-thinning medication

Anticoagulant and antiplatelet medicines include:

• warfarin;
• apixaban;
• rivaroxaban;
• edoxaban;
• dabigatran;
• aspirin;
• clopidogrel.

These medicines can make bleeding more noticeable or more prolonged. They should not, however, automatically be accepted as the underlying explanation for haematuria.

Blood-thinning treatment may reveal bleeding from a stone, enlarged prostate, infection or tumour that would otherwise have remained unnoticed. Patients taking anticoagulants should therefore be assessed according to the same underlying risk principles as other patients.

Medication should not be stopped without advice from the clinician responsible for prescribing it, as doing so may create a serious risk of stroke, thrombosis or another cardiovascular event.

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10. Recent procedures, catheterisation or injury

Blood may appear after:

• insertion or removal of a urinary catheter;
• flexible cystoscopy;
• prostate biopsy;
• ureteroscopy;
• prostate or bladder surgery;
• kidney surgery;
• radiotherapy;
• trauma to the abdomen, back or pelvis.

A small amount of bleeding may be expected after some procedures, but persistent, heavy or recurrent bleeding should be reviewed.

Following significant trauma, haematuria may indicate injury to the kidney, bladder or urethra and requires urgent assessment.

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11. Previous pelvic radiotherapy or chemotherapy

Radiotherapy to the prostate, bladder, rectum, cervix or other pelvic organs can cause fragile blood vessels to develop in the bladder lining.

Radiation-related bleeding may begin months or even years after treatment. It should not be assumed to be harmless, because previous pelvic radiotherapy also increases the importance of excluding a new urinary tract tumour.

Certain chemotherapy drugs, particularly cyclophosphamide and ifosfamide, can damage the bladder lining and increase the risk of haemorrhagic cystitis and later bladder malignancy.

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12. Strenuous exercise

Intense exercise, especially prolonged running, can occasionally cause temporary haematuria.

Exercise-related haematuria usually clears after a period of rest. Persistent bleeding, recurrent episodes or visible haematuria in someone with cancer risk factors should not simply be attributed to exercise without assessment.

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13. Gynaecological and non-urinary bleeding

Blood seen while passing urine may not always have come from the urinary tract.

Possible alternative sources include:

• menstruation;
• vaginal bleeding;
• postmenopausal bleeding;
• cervical or uterine conditions;
• rectal bleeding;
• urinary-tract endometriosis.

A carefully collected urine sample may help distinguish urinary blood from contamination. In some women, a gynaecological examination or separate investigation may be appropriate.

A plausible gynaecological source does not necessarily remove the need for urological assessment when the patient also meets haematuria referral criteria.

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14. Urine discolouration that is not blood

Red or dark urine is not always caused by haematuria.

Possible causes include:

• beetroot;
• food colouring;
• rifampicin;
• some urinary analgesics;
• certain chemotherapy medicines;
• muscle breakdown releasing myoglobin;
• destruction of red blood cells releasing haemoglobin;
• dehydration producing highly concentrated urine.

A urine dipstick and, where necessary, laboratory testing can help determine whether the discolouration represents genuine urinary bleeding.

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15. Less common causes

Less frequent causes of haematuria include:

• renal infarction;
• abnormalities of the renal blood vessels;
• papillary necrosis associated with diabetes, sickle-cell disease or analgesic use;
• urinary schistosomiasis following exposure in an endemic region;
• genitourinary tuberculosis;
• ketamine-related bladder injury;
• hereditary bleeding disorders;
• low platelet counts;
• structural abnormalities of the urinary tract.

Travel history, ethnicity, medication use and previous medical treatment can therefore be important parts of the assessment.

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How is blood in the urine investigated?

There is no single test that examines the entire urinary system perfectly.

A complete assessment may require a combination of:

• medical history and examination;
• urine testing;
• blood tests;
• imaging of the kidneys and ureters;
• direct inspection of the bladder with a cystoscope.

The exact combination should be tailored to the individual’s risk rather than automatically performing every possible test.

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Step 1: Establish whether the blood is genuinely urinary

The first step is to clarify:

• whether the blood was visibly mixed with the urine;
• whether it may have originated from the vagina or rectum;
• whether a food or medicine could have changed the urine colour;
• whether a dipstick result was trace or at least 1+;
• whether the finding is persistent.

Visible haematuria should be medically assessed even if it happened only once. The urgency and extent of urological investigation will depend on age, infection status, associated symptoms and risk factors.

For an isolated non-visible dipstick finding in an otherwise well, low-risk person, repeat testing and assessment for kidney disease may be more appropriate than immediate invasive investigation.

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Step 2: Take a detailed clinical history

The history helps identify both likely causes and the risk of urinary tract cancer.

Your doctor or urologist may ask about:

• whether the blood was visible or found only on testing;
• whether it occurred at the beginning, end or throughout urination;
• whether clots were present;
• pain in the back, side, abdomen or groin;
• burning, frequency or urgency;
• difficulty emptying the bladder;
• fever or recent infection;
• weight loss or loss of appetite;
• previous stones;
• previous bladder, kidney or prostate conditions;
• recent catheterisation, surgery or trauma;
• smoking history;
• occupational chemical exposure;
• previous radiotherapy or chemotherapy;
• blood-thinning medication;
• travel to areas where schistosomiasis or tuberculosis is more common;
• family history of kidney disease or urinary cancer.

Smoking remains particularly important because bladder-cancer risk rises with cumulative exposure and does not immediately return to normal after stopping.

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Step 3: Physical examination

The examination is guided by the history and may include:

• examination of the abdomen;
• assessment of the flanks and kidneys;
• blood-pressure measurement;
• examination of the external genitalia;
• rectal examination of the prostate in men;
• vaginal examination where a gynaecological source is possible.

Many patients with haematuria have a normal physical examination. This does not remove the need for appropriate urine testing, imaging or cystoscopy.

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Step 4: Urine tests

Urine dipstick

A dipstick can detect blood, protein, white blood cells, nitrites and other markers.

A result of 1+ blood or greater is considered significant when assessing haematuria. NICE does not require routine microscopy merely to confirm a positive dipstick.

Urine culture

A midstream urine sample may be sent to the laboratory to look for infection.

When infection is confirmed, it should be treated appropriately. Persistent or recurrent visible haematuria after successful treatment requires further assessment.

Urine albumin-to-creatinine ratio

An albumin-to-creatinine ratio, usually abbreviated to ACR, measures protein leakage from the kidneys.

Protein together with blood in the urine may point towards glomerular or chronic kidney disease rather than an isolated bladder problem.

Urine microscopy

Microscopy may still be useful in selected circumstances—for example, when distinguishing urinary blood from haemoglobin or myoglobin, assessing suspected kidney disease or examining the urine sediment.

It is not routinely required simply to verify every positive dipstick result.

Urine cytology

Urine cytology examines shed urinary cells under a microscope for features of high-grade cancer.

It is not recommended as a routine first-line test for every patient with haematuria because it is relatively insensitive for low-grade bladder tumours and can produce uncertain results.

It may be helpful in selected cases, including persistent unexplained haematuria or symptoms raising concern about carcinoma in situ, such as persistent bladder pain and irritative urinary symptoms.

Urinary biomarker tests

Several newer urine tests analyse DNA, RNA, proteins or chromosomal changes associated with bladder cancer.

These tests are an important area of research, particularly as potential tools for identifying very-low-risk patients who may not require cystoscopy. They are not currently recommended as routine replacements for cystoscopy in UK haematuria pathways.

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Step 5: Blood tests

Common blood tests include:

Kidney function

Creatinine and estimated glomerular filtration rate, or eGFR, assess how well the kidneys are working.

Kidney function is also important when deciding whether iodinated contrast can safely be used for a CT scan.

Full blood count

This may show:

• anaemia caused by significant or prolonged bleeding;
• a raised white blood-cell count suggesting infection or inflammation;
• abnormalities of the platelets.

Clotting tests

These may be appropriate when there is heavy bleeding, liver disease, a known bleeding disorder or treatment with warfarin.

PSA test

A PSA blood test may be offered to some men depending on their age, prostate symptoms and clinical circumstances.

Prostate cancer is not a common cause of visible haematuria, and PSA is not a test for bladder or kidney cancer. The advantages and limitations of PSA testing should therefore be discussed before it is performed.

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Who needs an urgent suspected-cancer referral?

Current NICE guidance recommends referral through a suspected-cancer pathway for bladder cancer when a person is:

• aged 45 or over with unexplained visible haematuria in the absence of urinary infection; or
• aged 45 or over when visible haematuria persists or returns after successful treatment of a urinary infection; or
• aged 60 or over with unexplained non-visible haematuria together with painful urination or a raised white blood-cell count.

The visible-haematuria criteria also trigger consideration of renal cancer. NICE advises considering a non-urgent bladder-cancer referral in people aged 60 or over with recurrent or persistent unexplained urinary infection.

These age thresholds guide urgent NHS referral. They do not mean that younger people should never be investigated. Clinical judgement remains important when there is recurrent visible bleeding, a strong smoking history, significant occupational exposure, previous pelvic radiotherapy or another concerning feature.

Conversely, asymptomatic non-visible haematuria outside the NICE suspected-cancer criteria does not usually require an urgent bladder-cancer pathway. Kidney causes, symptoms and individual risk factors should first be assessed, with non-urgent referral considered where appropriate.

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Flexible cystoscopy

Flexible cystoscopy is the principal test used to inspect the urethra and bladder.

A thin, flexible telescope is passed gently through the urethra under local anaesthetic gel. The procedure usually takes only a few minutes.

It allows the clinician to examine:

• the urethra;
• the prostate channel in men;
• the bladder lining;
• the openings of the ureters into the bladder;
• any stones, inflammation, narrowing or abnormal growths.

Most patients describe temporary discomfort or a stinging sensation rather than severe pain.

A small amount of blood or mild burning when passing urine can occur for a short time afterwards. Patients are given advice about symptoms that should prompt medical review.

Flexible cystoscopy remains the cornerstone of bladder investigation because an ultrasound or CT scan can miss small or flat abnormalities of the bladder lining. Current GIRFT guidance recommends offering it early in the pathway and documenting any abnormality with its size, position and appearance.

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Ultrasound of the kidneys and bladder

An ultrasound scan uses sound waves rather than radiation.

It can assess:

• the size and appearance of the kidneys;
• larger kidney masses;
• kidney stones in some locations;
• swelling of a kidney caused by obstruction;
• bladder volume;
• residual urine after urination;
• larger bladder abnormalities;
• prostate enlargement.

Ultrasound is safe, widely available and does not require an injection of contrast.

Its limitations are important. Ultrasound may not identify:

• small bladder tumours;
• flat bladder abnormalities;
• small ureteric tumours;
• some ureteric stones;
• subtle abnormalities of the renal collecting system.

A normal ultrasound therefore does not always remove the need for flexible cystoscopy or more detailed imaging.

Current risk-stratified pathways favour ultrasound for lower-risk patients—for example, some younger non-smokers with non-visible haematuria and no additional urological symptoms.

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CT urography

CT urography is a specialised CT examination of the urinary tract.

It usually involves an injection of iodine-containing contrast followed by scans taken at carefully timed stages. This allows detailed assessment of:

• kidney tissue;
• the renal collecting systems;
• the ureters;
• the bladder;
• surrounding lymph nodes and abdominal structures.

CT urography is particularly valuable when there is a higher risk of urothelial cancer or an abnormality of the upper urinary tract.

Factors that may favour CT urography include:

• visible haematuria;
• older age;
• smoking;
• male sex;
• previous pelvic radiotherapy;
• relevant occupational exposure;
• an abnormal ultrasound;
• concern about a ureteric or renal-pelvis tumour.

CT urography involves radiation and iodinated contrast, so it should not automatically be performed in every patient with a positive urine dipstick. Current GIRFT guidance recommends reserving it for patients at higher cancer risk and using ultrasound for appropriate lower-risk patients.

Kidney function, allergies, frailty and other medical conditions are considered before contrast is given.

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CT scan for suspected stones

When symptoms strongly suggest a ureteric stone, a different type of CT may be used.

A low-dose CT scan without contrast is highly effective at identifying most urinary stones and showing whether the kidney is obstructed.

This is not the same as a full CT urogram. The correct scan depends on the clinical question:

• a non-contrast CT is usually used primarily to look for stones;
• CT urography is designed to assess the urinary lining and investigate possible cancer or other structural disease.

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MRI and MR urography

MRI uses magnetic fields rather than ionising radiation.

MR urography may be considered when:

• iodinated CT contrast cannot be used;
• radiation exposure is a particular concern;
• the patient is pregnant;
• a CT finding needs further characterisation;
• more detailed soft-tissue assessment is required.

MRI does not replace CT urography in every situation. It is less suitable for detecting many urinary stones and may not be as widely available.

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When are ureteroscopy and retrograde studies needed?

Occasionally, CT or MRI identifies an abnormality in the ureter or renal collecting system that cannot be diagnosed with confidence.

Further tests may include:

Retrograde pyelography

Contrast is introduced directly into the ureter during cystoscopy, allowing X-ray images of the ureter and renal collecting system.

Ureteroscopy

A very thin telescope is passed through the bladder and into the ureter. It allows direct inspection of the ureter and kidney drainage system, with biopsy of any suspicious area.

Selective upper-tract cytology

A urine sample may be collected directly from one ureter to determine which side is producing abnormal cells or bleeding.

These are not routine first-line tests for most patients. They are reserved for situations in which standard imaging is abnormal, incomplete or does not explain persistent bleeding.

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What is a one-stop haematuria clinic?

A one-stop haematuria clinic aims to complete the principal diagnostic assessment during a single hospital visit.

Depending on local arrangements and individual risk, the appointment may include:

• review by a urology clinician;
• urine testing;
• examination;
• flexible cystoscopy;
• ultrasound or other imaging;
• discussion of the initial findings.

Some services perform imaging before the cystoscopy appointment. Others use the cystoscopy and risk assessment to decide whether additional imaging is necessary.

Current GIRFT guidance recommends same-day core diagnostics and identifies one-stop haematuria clinics offering cystoscopy and appropriately selected imaging as the preferred model for reducing delays and repeated hospital visits.

Not every patient needs every test on the same day. The objective is an efficient, individualised pathway rather than indiscriminate testing.

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What if cystoscopy and imaging are normal?

A normal investigation is reassuring and is the most common outcome.

Possible explanations after a negative assessment include:

• a urinary infection that has resolved;
• minor prostatic bleeding;
• a small stone that has passed;
• temporary exercise-related haematuria;
• a benign kidney condition;
• no identifiable cause.

A negative investigation should still be accompanied by clear safety-netting.

Further review may be appropriate if:

• visible haematuria recurs;
• clots develop;
• urinary symptoms change;
• kidney function deteriorates;
• protein appears in the urine;
• blood pressure rises;
• unexplained pain, weight loss or systemic symptoms develop.

For persistent isolated non-visible haematuria without proteinuria, NICE advises ongoing annual monitoring of blood pressure, kidney function and urine protein while the haematuria continues.

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Frequently asked questions about blood in the urine

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Private assessment for blood in the urine

A private urology consultation can be helpful when:

• you have experienced visible blood in the urine;
• blood has recurred after treatment for infection;
• a urine dipstick repeatedly shows blood;
• you are taking anticoagulants and the cause of bleeding is uncertain;
• you have had an ultrasound but remain concerned;
• you would like an explanation of whether cystoscopy or CT urography is appropriate;
• you require a second opinion on previous haematuria investigations.

Mr Neil Haldar is a Consultant Urological Surgeon with extensive experience in the assessment of haematuria, bladder conditions, kidney disease, prostate disorders and urological cancer.

During a consultation, he will review the nature of the bleeding, relevant risk factors, previous urine and blood results, medication and any existing scans before recommending a proportionate investigation pathway.

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About Mr Neil Haldar

Mr Neil Haldar is a Consultant Urological Surgeon practising in Buckinghamshire, Oxfordshire, Berkshire and London. His specialist interests include urological cancer, robotic and minimally invasive surgery, prostate and bladder conditions, kidney disease and general urology.

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This article is intended for general information and does not replace an individual medical assessment. Seek prompt medical advice for visible blood in the urine. Attend urgent or emergency care if you are unable to pass urine, are passing large clots, are bleeding heavily, or feel acutely unwell.