Quick answer. Blood in the urine (haematuria) should always be investigated, even after a single episode and even when there is no pain. In Singapore the commonest causes are urinary infections and stones, but painless blood can be an early sign of bladder or kidney cancer.
Blood in the urine is called haematuria. It may be visible (urine looks pink, red or brown) or non-visible (microscopic), picked up only on a urine test. Either type matters.
Many people ignore a one-off episode, especially when it is painless. Do not. A single episode of visible haematuria warrants medical assessment, because painless bleeding can be the first sign of a serious problem.
At a glance
| Possible cause | What it may suggest | Urgency |
|---|---|---|
| Urinary tract infection (UTI) | Burning, frequency, urgency, sometimes fever | See a doctor within days; urgently if fever or back pain |
| Kidney or bladder stones | Sudden severe loin or abdominal pain, often with visible blood | Urgent; go to A&E if pain is severe or there is fever |
| Enlarged prostate (men) | Difficulty passing urine, weak stream, dribbling | See a doctor soon for assessment |
| Bladder or kidney cancer | Painless visible blood, especially over age 40 or smokers | See a doctor promptly even if it settles |
| Kidney inflammation (glomerulonephritis) | Microscopic blood, sometimes with protein, swelling or high blood pressure | See a doctor; may need a kidney specialist |
What is haematuria?
Haematuria simply means blood in the urine. Visible (gross) haematuria turns the urine pink, red or cola-coloured. Non-visible (microscopic) haematuria is detected only on a urine dipstick or microscopy and is often found incidentally during a health screening or routine test.
Both visible and non-visible haematuria need to be investigated. The amount of blood you can see does not reliably tell you how serious the cause is — even a small, painless trace can be significant.
Common versus serious causes
In Singapore, three of the commonest causes of blood in the urine are urinary infections, stones, and growths or cancers of the kidney, ureter, bladder or prostate. In younger people, stones and UTIs are most common. In older people — particularly those over 40 and smokers — painless visible blood is more likely to be linked to bladder or kidney cancer.
Other causes include an enlarged prostate, vigorous exercise, certain medicines such as blood thinners, and inflammation of the kidney filters (glomerulonephritis). Some foods (such as beetroot) and medications can colour urine red without any actual blood, which is why a urine test is needed to confirm true haematuria.
When to see a doctor urgently
Call 995 or go to A&E immediately if you have:
- Heavy bleeding, large clots, or you are unable to pass urine
- Blood in the urine with high fever, chills, severe back or abdominal pain (possible serious infection or obstructed stone)
- Feeling faint, dizzy, or signs of significant blood loss
See a doctor promptly (do not wait) if you notice:
- Any visible blood in the urine, even once, and even if it is painless
- Microscopic blood found on a urine test
- Blood with weight loss, fatigue, or a change in your urinary habits
Painless visible haematuria is a recognised red flag for urinary tract cancer and must be investigated, even if the bleeding stops on its own.
How blood in the urine is investigated
Assessment usually starts with a urine test (to confirm blood and look for infection), urine sent to check for abnormal cells, and blood tests for kidney function. Depending on the findings, the doctor may arrange imaging of the kidneys and urinary tract (ultrasound or a CT scan) and, in many adults with visible haematuria, a cystoscopy — a thin camera passed into the bladder to look directly at the bladder lining.
These tests are done to find or rule out treatable causes such as stones and infection, and to exclude cancer early, when it is most treatable.
Which specialist should you see?
Start with your GP or a polyclinic, who can do the first urine and blood tests and refer you onward. For blood in the urine, you will usually be referred to one of the following:
- Urologists — specialists in the bladder, prostate, ureters and urinary tract, who perform cystoscopy and manage stones, prostate problems and urinary cancers.
- Nephrologists (kidney specialists) — for blood linked to kidney inflammation, abnormal kidney function, or protein in the urine.
If a urine test shows mainly microscopic blood with protein or reduced kidney function, a nephrologist is often the right specialist. If there is visible blood, stones, or a suspected growth, a urologist is usually involved.
What to expect at the appointment
Your doctor will ask whether the blood was visible or found on a test, whether it was painful, and about associated symptoms such as burning, frequency, fever, loin or abdominal pain, and any weight loss. Smoking history matters, as smoking raises the risk of bladder cancer. Expect a urine test to confirm blood and check for infection, urine sent to look for abnormal cells, and blood tests for kidney function. Depending on the findings, imaging of the kidneys and urinary tract, and in many adults with visible bleeding a cystoscopy, may be arranged. Bring a list of your medicines, as blood thinners and some other drugs are relevant.
Special situations and self-care
Some foods such as beetroot, and certain medicines, can colour the urine red without any actual blood, which is why a urine test is needed to confirm true haematuria. Strenuous exercise can occasionally cause temporary blood in the urine that settles with rest. In women, bleeding during a menstrual period can contaminate a urine sample, so it is worth mentioning the timing or repeating the test afterwards. None of these explanations should be assumed; visible blood, even once and even if painless, still warrants assessment because it is a recognised warning sign for urinary tract cancer.
Common questions
The bleeding stopped after one episode. Do I still need to see a doctor?
Yes. A single episode of visible blood in the urine should be assessed, because painless bleeding that settles on its own can still be the first sign of a serious problem.
Is microscopic blood found on screening serious?
It needs to be checked, but it is often due to a benign cause. Your doctor will decide what tests are appropriate based on your age, symptoms and risk factors.
Related guides
- Best Urology Clinics in Singapore — our editorial shortlist
- urology clinics directory
- Gastroenterology
- Oncology
- Oncology
Sources
- SingHealth – Haematuria (Blood in Urine): Causes & Treatments
- National University Hospital (NUH) – Microscopic Haematuria
- NHS – Blood in urine
- Mayo Clinic – Blood in urine (hematuria)
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