Blood in urine — hematuria — is one of the most frequent reasons for urological referral and almost invariably causes alarm. The reassuring fact is that, in the majority of patients, the cause proves to be a treatable condition such as urinary tract infection, urolithiasis or benign prostatic enlargement. The cautionary fact is that painless, self-limiting hematuria may be the first and sometimes the only manifestation of bladder cancer, and it is precisely the symptom most often dismissed with the reasoning "it stopped, so it cannot be serious." This article reviews the causes of hematuria, the differences between men and women, the findings that constitute an emergency, and the investigations recommended by current guidelines.

Definition: visible and microscopic hematuria

Hematuria denotes an abnormal number of red blood cells in the urine and presents in two forms:

• Gross (visible) hematuria: the urine appears pink, red, brown or tea-coloured. As little as 1 mL of blood per litre of urine produces a visible colour change, so intensely red urine does not necessarily indicate heavy bleeding.
• Microscopic hematuria: the urine is normal in colour and blood is detected only on urinalysis. According to the current American Urological Association / SUFU guideline, microhematuria is defined as three or more red blood cells per high-power field on microscopic examination of a properly collected specimen. A positive dipstick alone is insufficient and must be confirmed by microscopy.

Both forms warrant attention. The probability of an underlying malignancy is approximately 10–20% in gross hematuria and 2–5% in microhematuria; consequently, visible bleeding — however brief — always merits complete urological evaluation.

Bleeding may originate anywhere from the kidney to the urethra; the urine may appear pink, red or tea-coloured. Microscopic hematuria is invisible and detected only on urinalysis.

Red urine without bleeding: pseudohematuria

The first step is to establish whether blood is genuinely present. Beetroot, blackberries and red food dyes; rifampicin, nitrofurantoin, phenazopyridine, certain laxatives and chemotherapeutic agents may impart a red-orange colour to the urine. Muscle breakdown after extreme exertion (myoglobinuria) and certain haematological disorders also darken the urine. In women, contamination by menstrual blood is a frequent source of confusion, and urinalysis should be repeated after menstruation. Microscopy distinguishes all of these from true hematuria.

Causes of hematuria

Bleeding may originate at any level of the urinary tract, from the kidney to the urethral meatus:

• Urinary tract infection (cystitis, pyelonephritis): the most common cause, particularly in women, accompanied by dysuria, frequency and suprapubic pain. Urinalysis should be repeated 4–6 weeks after treatment; persistent hematuria requires further evaluation. Recurrent infections are discussed in "Etiology of Recurrent Urinary Tract Infections (Cystitis)".
• Renal and ureteric stones: stone passage abrades the urothelium, and hematuria typically accompanies severe flank pain radiating to the groin. Stone disease is the leading consideration when hematuria coexists with groin pain; see our Stone Disease page.
• Benign prostatic hyperplasia (BPH): dilated surface vessels of an enlarged prostate are a common cause of painless bleeding in men over 50 — a diagnosis that should only be accepted once bladder cancer has been excluded.
• Prostatitis and urethritis: inflammatory conditions producing painful voiding with bleeding.
• Bladder cancer: classically presents as painless gross hematuria, which may be intermittent. In smokers over 50 it is the first diagnosis to exclude. Treatment is described on our Bladder Cancer Treatment page.
• Renal and upper-tract urothelial tumours: the classical triad of hematuria, flank pain and palpable mass is now rare, and most renal tumours are detected incidentally; hematuria nonetheless remains an important warning sign (Kidney Tumours).
• Prostate cancer: rarely presents with hematuria, although it may occur in advanced disease (see "Prostate Cancer Symptoms").
• Glomerular (nephrological) disease: IgA nephropathy, post-infectious glomerulonephritis and thin basement membrane disease produce hematuria with proteinuria, dysmorphic erythrocytes and casts; these patients are managed by nephrology.
• Trauma, catheterisation and strenuous exercise: exercise-induced hematuria after long-distance running typically resolves within 72 hours; persistence requires investigation.
• Medications: anticoagulants unmask bleeding more readily, yet guidelines are explicit that anticoagulant use does not explain hematuria and these patients require the same complete evaluation. Cyclophosphamide and pelvic radiotherapy may cause haemorrhagic cystitis.
• After urological procedures: mild bleeding for several days after prostate, stone or bladder surgery and after ureteral stent placement is expected; the warning signs are described in "What Should Patients with a Ureteral Stent Watch Out For?".

Hematuria in men and women

In men, hematuria is increasingly associated with prostatic enlargement, stones and bladder tumours as age advances. Because urinary tract infection is far less common in men than in women, attributing male hematuria to "infection" without evaluation is inappropriate. Painless hematuria in a male smoker over 50 is considered bladder cancer until proven otherwise.

In women, the majority of cases are due to cystitis; however, bleeding that persists despite treatment or occurs without infective symptoms must be evaluated for tumours and stones in women as well. It is important to distinguish urinary bleeding from vaginal bleeding and from bleeding at the urethral meatus (for example, a post-menopausal urethral caruncle); clinical examination resolves this distinction when the complaint is blood noticed on tissue after voiding. Evidence indicates that evaluation is more often delayed in women and that bladder cancer is diagnosed at a more advanced stage; persistent hematuria in women should therefore be taken equally seriously.

Timing and clots: clues to the source

The phase of micturition in which blood appears helps localise the source. Bleeding at the start of the stream generally arises from the urethra; bleeding at the end suggests the bladder neck or prostatic urethra; bleeding throughout the stream indicates the bladder, ureter or kidney. Clots signify bleeding that is not trivial: long, vermiform clots suggest an upper-tract (ureteric or renal) origin, whereas large, irregular clots suggest the bladder. Clot retention with inability to void requires urgent intervention.

When is hematuria an emergency?

Immediate presentation to an emergency department is warranted in the following circumstances:

• Bleeding with clots and inability to pass urine;
• Bleeding accompanied by fever, rigors or severe flank pain;
• Dizziness, palpitations or weakness suggesting significant blood loss;
• Hematuria following an accident, fall or blunt trauma;
• Marked bleeding while taking anticoagulants.

Which specialist, and which investigations?

Hematuria is the province of urology; where proteinuria, oedema, hypertension or impaired renal function coexist, evaluation is shared with nephrology. The work-up is stratified by age, smoking history and the degree of hematuria. The AUA/SUFU guideline classifies microhematuria as low, intermediate or high risk according to age, cumulative tobacco exposure, red-cell count and any prior episode of gross hematuria; gross hematuria is treated as high risk at any age.

1. History and examination: timing of bleeding, associated pain or fever, tobacco use and occupational exposure (dyes, chemicals, rubber and leather industries), medications, and family history of urological malignancy.
2. Urinalysis with microscopy and urine culture: infection is treated and urinalysis repeated; hematuria persisting after resolution of infection cannot be attributed to that infection.
3. Renal function tests and, in men of appropriate age, PSA.
4. Imaging: renal and bladder ultrasound in low- and intermediate-risk patients; contrast-enhanced CT urography (or MR urography where renal function precludes contrast) in high-risk patients and in all cases of gross hematuria, to visualise the upper tracts in detail.
5. Cystoscopy: direct inspection of the bladder with a flexible endoscope under local anaesthesia, performed in the outpatient setting within minutes. Imaging does not substitute for cystoscopy in the diagnosis of bladder tumours, as small lesions are frequently invisible on ultrasound and CT. According to the guideline, cystoscopy is indicated in men over 40, women over 50, smokers and patients with other risk factors (the intermediate- and high-risk groups), and in every patient with gross hematuria; in younger low-risk patients, either cystoscopy or repeat urinalysis at six months is chosen through shared decision-making.
6. Urine cytology: used in high-risk patients as an adjunct to cystoscopy.

In a substantial proportion of patients no cause is identified; the likelihood of malignancy in this group is low, and periodic urinalysis suffices. Recurrent gross hematuria prompts repeat evaluation.

Hematuria in children

The causes of hematuria in children differ from those in adults: urinary tract infection, hypercalciuria, post-streptococcal glomerulonephritis, IgA nephropathy, stones, trauma and congenital anomalies predominate, while tumours are rare. Isolated microscopic hematuria detected on urinalysis is usually benign in children and is monitored with repeat testing. Gross hematuria, or hematuria accompanied by proteinuria, oedema, hypertension or impaired renal function, requires evaluation by paediatric nephrology and paediatric urology.

Treatment is directed at the cause

Hematuria is a sign, not a disease, and management targets the underlying condition. Infections are treated with antibiotics; stones are managed according to size and location by medical expulsive therapy, ESWL, RIRS or PCNL; benign prostatic enlargement is treated medically or surgically, for example with HoLEP. Bladder tumours are resected endoscopically (TURBT) and further treatment is guided by pathology; in renal tumours, nephron-sparing partial nephrectomy is preferred whenever feasible. Mild microhematuria without an identifiable cause requires surveillance rather than treatment.

Frequently Asked Questions

Is blood in urine serious?

It is most often due to a treatable cause such as infection, stones or prostatic enlargement; however, painless hematuria in particular may be the first sign of a bladder or kidney tumour. It should never be regarded as insignificant until the cause has been established.

What does painless blood in urine mean?

Painless visible hematuria, especially in smokers over 50, is regarded as bladder cancer until proven otherwise. Infection and stones are usually accompanied by pain or burning.

Can a urinary tract infection cause blood in urine?

Yes; hematuria during cystitis is common (haemorrhagic cystitis). Urinalysis should nonetheless be repeated after antibiotic treatment, and persistent hematuria requires further investigation.

My urinalysis shows blood but my urine looks normal — what should I do?

This is microscopic hematuria. It is first confirmed by microscopy, and transient causes such as infection, menstruation or strenuous exercise are excluded. Ultrasound and, depending on age and risk factors, cystoscopy are then planned.

Which doctor should I see for blood in urine?

A urologist. Where proteinuria, hypertension or impaired renal function coexist, joint evaluation with a nephrologist is arranged.

I take blood thinners — is blood in my urine normal?

No. Anticoagulants facilitate bleeding from an existing lesion; guidelines recommend that these patients undergo the same complete evaluation as any other.

Is blood in the urine normal after kidney stone or prostate surgery?

Mildly pink-red urine is expected in the first days. Clots, inability to void, fever or progressively increasing bleeding require contact with the surgical team or an emergency department.

This article is intended for general information only and does not constitute individual medical advice. Please consult your physician for diagnosis and treatment.

References

1. Barocas DA, Boorjian SA, Alvarez RD, et al. Microhematuria: AUA/SUFU Guideline. J Urol 2020;204(4):778-786.
2. Babjuk M, Burger M, Compérat E, et al. EAU Guidelines on Non-muscle-invasive Bladder Cancer (TaT1 and CIS). European Association of Urology, 2025. uroweb.org/guidelines/non-muscle-invasive-bladder-cancer
3. Türk EC, Skolarikos A, Neisius A, et al. EAU Guidelines on Urolithiasis. European Association of Urology, 2025. uroweb.org/guidelines/urolithiasis
4. Bonkat G, Bartoletti R, Bruyère F, et al. EAU Guidelines on Urological Infections. European Association of Urology, 2025. uroweb.org/guidelines/urological-infections
5. Ingelfinger JR. Hematuria in Adults. N Engl J Med 2021;385(2):153-163.
6. Bray F, Laversanne M, Sung H, et al. Global cancer statistics 2022: GLOBOCAN estimates of incidence and mortality worldwide. CA Cancer J Clin 2024;74(3):229-263.