Cystoscopy with NBI for blood in the urine in Taichung: uses, limits
The most worrying part of blood in the urine is often this: you have tests, and the cause is still not found. Some early changes in the bladder lining are hard to see under normal white light. This is a built-in limit of the standard test.
A cystoscopy is a look inside the bladder with a thin camera (an endoscope) passed through the urethra. Narrow band imaging (NBI) makes the lining and its small blood vessels stand out more clearly. It may help in checking blood in the urine and in following up bladder lesions. Whether you need it, and its benefits, limits and risks, must be judged for you by a urologist.
Explained by Dr. Chao-An Chen, urologist, at 昭安泌尿科診所 (Morning Urology Clinic), West District, Taichung.
In short
- What it is: a direct look at the inside of the bladder. It is the standard test for blood in the urine, whether you can see it or it is found only under a microscope.
- What NBI adds: it uses only blue and green light, so blood vessels near the surface show up more clearly. This can help the doctor notice flat changes that are hard to see in white light.
- Its limits: NBI is a support tool and cannot promise a result. Very small or flat lesions can still be missed, and false alarms happen. A biopsy (tissue test) gives the final diagnosis.
- The test: usually done within a few minutes. A local anaesthetic lubricating gel is put into the urethra first. You may still feel pressure, burning or pain.
- Cost: Costs are explained at the consultation. You can also ask about costs on LINE before you come.
Why a cystoscopy is the standard test
In urology, cystoscopy is the standard test for checking painless blood in the urine that you can see (painless gross haematuria), and also for blood found only under a microscope (microscopic haematuria).
Ultrasound and CT scans are useful for finding large, solid tumours. But some changes are very thin or very small. One example is carcinoma in situ (CIS): a high-grade cancer that grows only in the surface layer of the bladder lining and is flat, not raised. For these changes, scans cannot replace looking directly with an endoscope.
How narrow band imaging (NBI) works
A normal cystoscope uses white light. NBI is an optical method that keeps only two colours of light: blue light (415 nm) and green light (540 nm). Both go only a short way into tissue. Both are strongly absorbed by haemoglobin, the red substance in blood. So on the screen, the tiny blood vessels (capillaries) in the surface of the lining, and the veins deeper down, look clearer and darker.
Why does this matter? When a tumour grows, it often grows new blood vessels. Cancer of the bladder lining (urothelial carcinoma) often has many of these new vessels. With NBI, the doctor may find it easier to notice a flat lesion that is hard to see in white light.
NBI can help in finding and following up early lesions. But it only helps. The final diagnosis must still be confirmed by a biopsy, together with other tests.
Can a white-light cystoscopy miss something?
Yes, it can, and studies have tried to estimate how often. The European Association of Urology (EAU) 2026 bladder cancer guideline cites a pooled analysis (meta-analysis) of 27 studies with 2,949 people who were suspected of having new or returning bladder cancer. It was published in 2011 and included studies up to 2008.
Among people who really had bladder cancer, standard white-light cystoscopy found about 71% (95% confidence interval 49–93%, so the estimate is very uncertain). Fluorescence cystoscopy found about 92%. But fluorescence gave more false alarms: more people without cancer were judged as suspicious.
The difference was mainly in high-risk lesions. The guideline names carcinoma in situ in particular. For low-risk tumours that stick out from the lining, the two methods found about the same share.
How to read these numbers
- They come from people already known to have bladder cancer. They cannot tell you how many people with a normal cystoscopy really have cancer.
- They cannot be applied directly to people who had blood in the urine found at a general health check.
- Fluorescence cystoscopy is a different method: a light-sensitive drug is first put into the bladder. This analysis did not study NBI, so the 92% figure cannot be applied to NBI.
So a cystoscopy can still miss very small or flat lesions, such as carcinoma in situ. If something suspicious is seen, a biopsy is needed to confirm it. When a biopsy is taken, the pathology report decides. Please come back as arranged to get the report, so the doctor can explain it to you in person.
Why an ultrasound is not always enough
Think of the bladder as a balloon filled with water. An ultrasound is like shining a torch at the balloon from the outside. If there is a large stone inside, you can see its shadow. But if the inner wall has a few tiny red spots or a broken blood vessel, they are hard to see from outside.
A cystoscopy with NBI is like sending a camera into the balloon. The lining and its small blood vessels can be seen more clearly. Still, the view depends on how much bleeding there is, how full the bladder is, and where a lesion sits. Not every corner can always be fully checked.
| Kidney and bladder ultrasound | Cystoscopy with the WOLF imaging system | |
|---|---|---|
| Image | Black-and-white image made from sound waves; limited detail | High-resolution images help to see the lining and small blood vessels |
| Small lesions | Hard to judge very small lesions or flat carcinoma in situ | The surface is seen directly, so there is a better chance of finding small or flat lesions |
| Blood vessels | Cannot show the pattern of small vessels on the surface | NBI makes the vessel pattern stand out, which helps recognition |
| Role | First, non-invasive screening test | Helps find where the bleeding comes from, and follows up bladder lesions |
Who may need it, and how the test goes
- Common reasons: blood in the urine, checking bladder symptoms, and follow-up of bladder lesions. If you smoke, have long-term contact with chemical dyes, or have had urothelial carcinoma and need regular checks, the doctor may suggest a cystoscopy. Whether it is done still depends on your own situation.
- A careful decision first: any invasive test needs a careful medical decision. The doctor plans tests based on your age, symptoms and medical history. Not everyone with blood in the urine needs a cystoscopy right away. Your smoking history, your age and the way the blood appears help decide whether you need one.
- Reducing discomfort: many people feel nervous about this test. Before it starts, a local anaesthetic lubricating gel is put into the urethra to reduce discomfort. You may still feel pressure, burning or pain during and after the test. This varies a lot from person to person and cannot be fully avoided. The test usually takes a few minutes.
Risks, side effects and limits
A cystoscopy is an invasive test, with or without NBI. These are its real risks and limits. Please discuss them with the doctor before the test.
- Common discomfort and complications. During the test and for a few days after, you may have burning or stinging when you pass urine, need to pass urine more often, feel lower belly pressure or pain, or see a little blood in the urine. Most of this settles by itself. A few people get a urinary tract infection or an injury to the lining of the urethra. Very rarely, a person cannot pass urine (urinary retention) and needs a tube (catheter) for a short time.
- What NBI cannot do. NBI is a support tool that raises the contrast of the lining and small vessels. It cannot replace a biopsy. What the doctor can see depends on bleeding, how full the bladder is, inflammation and where a lesion sits. False alarms (false positives) can still happen, and some lesions may not be seen.
- Everyone is different. Pain and discomfort vary. Men have a longer urethra. If you have an enlarged prostate, a narrowed urethra (urethral stricture) or past urinary tract surgery, passing the scope may be less smooth. The local anaesthetic gel reduces discomfort but cannot prevent all pain.
- Tell the doctor first; the test may be delayed. An acute urinary tract infection, fever, large blood clots blocking the flow, a clearly narrowed urethra, taking blood thinners (anticoagulants), a weak immune system, or an allergy to local anaesthetics. The doctor decides whether to delay the test or treat the problem first.
- A normal result is not the end. A normal result does not mean you never need follow-up. Whether you need a cystoscopy, and whether NBI is added, must be decided by a urologist in person, based on your age, symptoms, history and other test results.
After the test: results and follow-up
- The cystoscopy gives the doctor a direct view of the bladder wall. It is used to decide next steps, together with other tests and the pathology result.
- If a biopsy was taken, come back as arranged to hear the report from the doctor in person.
- If the result is normal but blood in the urine continues or comes back, come back to be checked again.
- If you already have a diagnosed bladder tumour and need regular cystoscopy checks, please come back at the times the doctor sets.
Frequently asked questions
The blood in my urine does not hurt. Can I wait?
Painless blood in the urine is still a signal from the body. It is better to see a urologist first. The doctor decides, based on your situation, whether you need a cystoscopy and when.
Does everyone with blood in the urine need a cystoscopy?
No, not always right away. Smoking history, age and the way the blood appears are used to sort people into low, middle and high risk. Each group has different recommended tests. See risk levels and tests for microscopic blood in the urine (Chinese).
My ultrasound was normal. Is my bladder fine?
Not necessarily. A normal ultrasound does not mean the bladder is fine. Flat carcinoma in situ often cannot be seen on scans from outside the body.
With NBI, will nothing be missed?
No test can promise that. NBI helps the doctor see the lining and small vessels more clearly, but small or flat lesions can still be missed, and false alarms can happen. A normal result does not mean you never need follow-up.
Does it hurt?
A local anaesthetic lubricating gel is used first. Still, pressure, burning or pain during and after the test are possible, and how it feels differs a lot between people. It usually takes a few minutes.
I am a woman. Is it different for me?
Women have a shorter urethra, so the scope goes a shorter distance and the discomfort is different from men. Blood in the urine can also come from infection or stones. If it keeps happening, the clinic arranges imaging and cystoscopy to rule out problems inside the bladder. See women’s urology: leaking urine, repeated cystitis and blood in the urine (Chinese).
Related pages
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- Low testosterone: self-assessment: urinary symptoms often change together with hormones and metabolism.
Appointments and access
Consultations are conducted in Mandarin, and can also be conducted in English.
If you or a family member has blood in the urine with no clear cause, book a urology consultation first. You can also ask about the process or book an assessment on LINE. You do not need to explain why you are here in the waiting area; the clinic has private consulting rooms.
昭安泌尿科診所 (Morning Urology Clinic)
No. 98, Boguan 2nd St., West District, Taichung City 403, Taiwan（403 臺中市西區博館二街98號）
Consulting hours: Monday to Saturday (closed Sunday). Online booking is open 24 hours.
This page was produced by 昭安泌尿科診所 (Morning Urology Clinic). Medical content last updated: October 2026 (same as the Traditional Chinese version). English version published: 5 November 2026. Medically reviewed by Dr. Chao-An Chen, urologist.
Sources: EAU Guidelines on Non-muscle-invasive Bladder Cancer 2026 (Update March 2026) (§5.11.1, §5.12, §5.12.1) / Mowatt G, et al. Photodynamic diagnosis of bladder cancer compared with white light cystoscopy: systematic review and meta-analysis. Int J Technol Assess Health Care 2011;27(1):3–10 (PubMed 21262078).
This page provides general medical information and does not replace an individual diagnosis or treatment plan.