Go to the emergency room now if you are passing clots and cannot urinate, if the bleeding is heavy or you feel faint or lightheaded, or if you have blood in your urine along with a fever or chills.
What counts as blood in the urine?
Doctors call blood in the urine hematuria. There are two kinds:
- Visible (gross) hematuria is blood you can see. Urine may look pink, red or dark brown, and you may see small clots.
- Microscopic hematuria is blood you cannot see. It shows up only on a urine test.
A quick dipstick test in the office can suggest blood, but it can also be positive for other reasons. A microscopic urinalysis, where the urine is examined under a microscope, confirms whether red blood cells are really there.
Not every red or dark color is blood. Beets, some berries and some medicines can tint urine, and dark amber urine is usually just concentrated. If you are not sure, have your urine checked.
What causes it?
Blood can come from anywhere along the urinary tract. That includes the kidneys, the ureters (the tubes that carry urine from each kidney to the bladder), the bladder, the prostate in men and the urethra (the tube that carries urine out of the body). Common causes include:
- Urinary tract infection. Often comes with burning, urgency or needing to urinate often.
- Kidney or bladder stones. A stone can scrape the lining as it moves. Pain in the side or back is common but not always present. See kidney stones.
- An enlarged prostate. An enlarged prostate can have fragile blood vessels on its surface that bleed from time to time. See enlarged prostate (BPH).
- Cancer. Cancer of the bladder, kidney or ureter can cause bleeding. Painless blood in the urine is the most common sign of bladder cancer.
- Other causes. Hard exercise, an injury, a recent catheter or procedure, and some kidney diseases.
Blood thinners, such as aspirin, warfarin or apixaban, make bleeding more likely, but they usually are not the whole explanation. If you bleed while taking one, you still need the same evaluation.
If it went away, do I still need to be checked?
Yes. This is the main point of this article.
Bleeding from a bladder tumor often comes and goes. You might see blood once, then have clear urine for weeks or months. The blood going away does not mean the cause has gone away.
Most people who are checked turn out to have a cause that is not cancer, or no clear cause at all. When the cause is a cancer, though, finding it early often means simpler treatment.
Key takeaway: one episode of visible blood in your urine is enough reason to see a urologist, even if it stopped on its own and even if you feel fine. Blood found only on a urine test also deserves follow-up.
What does the work-up involve?
A standard evaluation looks at the whole urinary tract. It usually starts with a urine test to check for infection. If there is an infection, it is treated, and your urine is checked again afterward to make sure the blood is gone. For visible blood, the evaluation then includes two main tests:
An imaging test, usually a CT scan
A CT scan looks at the kidneys and ureters, which can be a source of blood. It usually uses contrast dye given through a vein. If you cannot have contrast, an MRI or ultrasound may be used instead.
A cystoscopy
A look inside the bladder with a small camera on a thin tube, to check the bladder lining for tumors, stones or other sources of bleeding.
The two tests check different places, so you usually need both. A CT scan cannot reliably rule out a small tumor on the bladder lining, and a cystoscopy does not reach the kidneys. Sometimes a urine sample is also sent to a lab to look for abnormal cells.
When blood was found only on a urine test, how much testing makes sense depends on your risk. Dr. Su considers your age, your sex, your smoking history and how much blood was found. For some people, repeating the urine test or getting an ultrasound is a reasonable first step. For others, the full evaluation is the right call.
What does a cystoscopy feel like?
A cystoscopy to look for the source of bleeding is usually done in the office while you are awake. Numbing gel is placed in the urethra, and a thin, flexible scope with a camera at its tip is passed gently into the bladder. The bladder is filled with sterile water so the lining can be seen clearly, which can make you feel like you need to urinate.
The test itself takes about 1 to 2 minutes, and most patients tolerate it well. Many people feel pressure or a brief sting rather than real pain. Afterward, it is common to have some burning when you urinate and slightly pink urine for a day or so. Drinking extra water helps. Call the office if you get a fever, cannot urinate, or the burning gets worse instead of better.
Who is at higher risk for bladder cancer?
Anyone can get bladder cancer, but it is most common in adults over 60 to 65, and it is more common in men than in women. Risk is higher with:
- Smoking, now or in the past. Smoking is the most important known risk factor.
- Chemicals at work. Long-term exposure to harmful chemicals raises the risk for some workers, including hairdressers, painters, printers and dry cleaners.
- Past radiation therapy to the pelvis.
- Arsenic in drinking water.
If any of these apply to you, mention them at your visit. The bladder cancer page explains more.
Questions patients ask
I saw blood once and it stopped. Can I wait and see?
It is better not to. Bleeding from a serious cause often stops on its own for a while. Make an appointment soon rather than waiting to see whether it happens again.
I’m a woman. Isn’t this just a urinary infection?
Infections are a common cause, but they should be confirmed with a urine test. If blood is still there after the infection is treated, or you see blood without any infection symptoms, it deserves the same evaluation as in men. A menstrual period can affect a urine sample, so let the office know if you are having one.
I take a blood thinner. Doesn’t that explain it?
Usually not by itself. Blood thinners can make an existing problem bleed, so the source still needs to be found. Do not stop a blood thinner on your own; talk with the doctor who prescribed it.
Do I need both the CT scan and the cystoscopy?
For visible blood, usually yes, because each test looks at a different part of the urinary tract. If you cannot have a CT, other imaging can be used.
If you’d like Dr. Su to look at your results, book a visit or call the office nearest you. Bring any urine test results and scan reports you already have.