Hematuria is the general term for blood in your urine. Microhematuria (sometimes called microscopic hematuria) is a subtype of hematuria. With microhematuria, the red blood cells in your urine are so small, they can’t be seen with the naked eye. The cells can be seen only with a microscope during urinalysis. 

So, with microhematuria, when you glance at the toilet, your urine won’t look much different from the way it always looks. (Note: Some causes of hematuria, like bladder infections, may cause pain or burning sensations when you urinate.)

Most of the time, microhematuria isn’t a cause for alarm. But you don’t want to ignore it, either. Sometimes, it’s caused by a more serious health condition, such as bladder cancer. We’ll do some further testing to determine the cause. 

What causes blood in the urine? 

Microhematuria can be caused by a variety of conditions. Some are simple. For example, if you’ve worked out really hard (like running a marathon), you might have some blood in your urine. Hematuria can also be a side effect of medications. If that’s the case, we’ll review your prescriptions and see what can be adjusted. 

Other causes are more complicated. Some of the more common causes are: 

• Kidney or bladder stones
• Kidney infection
• Bladder, prostate, or kidney infections
• Urinary tract infection
• An enlarged prostate (also called benign prostatic hyperplasia or BPH)
• Bladder, prostate, or kidney cancer
• Sickle cell disease or other blood disorder
• Blood-clotting disorders (hemophilia)
• Polycystic kidney disease
• Sexually transmitted infections
• Trauma to the kidneys

Sometimes, the cause can’t be found, and hematuria clears up on its own. 

Finding out why there is blood in your urine. 

Once we’ve detected blood in your urine, we’ll do a full urological exam. If you’re a man, this might include a digital rectal exam. Women might have a pelvic exam. We’ll also ask you questions about your medical history and the medications you take. In addition, we’ll ask about your family’s medical history. Your answers to our questions will help us determine if you have any risk factors for bladder or kidney issues.

Based on your history and your symptoms, we’ll determine whether you are at low risk, intermediate risk, or high risk for certain urological conditions, like kidney stones or cancer. Then, we’ll talk together about next steps.

Low Risk

If you’re at low risk, we might have you come back in within 6 months for another urinalysis. We may also suggest the following two tests that can give us more information:

• Cystoscopy. This test allows us to see the inside of your bladder and urethra (the tube that urine passes through on its way out of your body) by using a cystoscope, a thin tube-shaped instrument. This test can be done here at the office, at an outpatient clinic, or in a hospital. It usually takes about 5 or 10 minutes, and you’ll likely be given local anesthesia or a numbing agent. 

If we notice any tissue abnormalities, a biopsy can be taken during the cystoscopy. That tissue will be examined with microscope. 

• Kidney ultrasound. This test uses sound waves to construct images of your kidneys. It’s also called a renal ultrasound. Further imaging tests, as described below, might be done at a later time.

We know that care decisions can be challenging. Be assured that we are here to answer all your questions!

If you decide not to have a cystoscopy or kidney ultrasound, and you still have blood in your urine after a subsequent urinalysis, you will probably fall into the intermediate risk category.

Intermediate Risk or High Risk

If you are at intermediate or high risk, we’ll recommend cystoscopy and a kidney ultrasound as described above. We’ll also talk to you about upper urinary tract imaging, which may include the following:

• CT scan. Computed tomography scans (often called “cat” scans) use X-rays to give us detailed images of your kidneys, bladder, and ureters (the two tubes that connect your kidneys and bladder). A CT scan can give us information about stones, infections, cysts, and tumors. 

• MR urography. MR stands for magnetic resonance. (You might be more familiar with the term magnetic resonance imaging or MRI.) If you are unable to have a CT scan, you might have MR urography, which provides images using radio waves.

• Retrograde pyelography. If you are unable to have a CT scan or MR urography, we might conduct a retrograde pyelography exam. This test uses X-rays along with a special dye injected into your ureters. This dye helps gives us a better view of your ureters and kidneys. Note: If you have a family history of kidney cancer or a genetic syndrome that increases your risk, we’ll most likely conduct imaging tests no matter what your risk level is.

Until we know more about your microhematuria, we encourage you to relax, though we know that can be easier said than done. And we understand that this is a lot of information to take in all at once. By all means, feel free to ask us any questions you have. We’ll take this process one step at a time. 

Resources

American Academy of Family Physicians

“Microscopic Hematuria”
(Last Updated: May 12, 2020)
https://familydoctor.org/condition/microscopic-hematuria/ 

American Urological Association

Barocas, D.A., et al.
“Microhematuria: AUA/SUFU Guideline”
(2020)
https://www.auanet.org/guidelines/microhematuria

Healthline

Sawyers, Tessa
“CT Scan vs. MRI”
(Updated: August 10, 2020)
https://www.healthline.com/health/ct-scan-vs-mri

Medscape

Babaian, Kara N., MD, FACS
“What is the role of upper urinary tract imaging in the diagnosis of bladder cancer?”
(Updated: December 30, 2020)
https://www.medscape.com/answers/438262-38704/what-is-the-role-of-upper-urinary-tract-imaging-in-the-diagnosis-of-bladder-cancer

National Institute of Diabetes and Digestive and Kidney Diseases

“Hematuria (Blood in the Urine)”
(July 2016)
https://www.niddk.nih.gov/health-information/urologic-diseases/hematuria-blood-urine 

UpToDate.com

Feldman, Adam S., MD, MPH
“Patient education: Blood in the urine (hematuria) in adults (Beyond the Basics)”
(Last updated: August 16, 2018)
https://www.uptodate.com/contents/blood-in-the-urine-hematuria-in-adults-beyond-the-basics 

Urology Care Foundation 

“How Blood in the Urine is Tested and Treated”
(October 14, 2020)
https://www.urologyhealth.org/careblog/how-blood-in-the-urine-is-tested-and-treated 

“What is Cystoscopy?”
https://www.urologyhealth.org/urologic-conditions/cystoscopy 

“What is Hematuria?”
https://www.urologyhealth.org/urologic-conditions/hematuria

“What is Retrograde Pyelography?”
https://www.urologyhealth.org/urology-a-z/r/retrograde-pyelography