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Am Fam Physician. 1999;60(4):1154

See related article on microscopic hematuria.

What is microscopic hematuria?

“Microscopic” means something is so small that it can only be seen through a special tool called a microscope. “Hematuria” means blood in the urine.

So if you have microscopic hematuria, you have red blood cells in your urine, but you can't see the blood when you urinate. Today your doctor wants to check a sample of your urine for blood.

How do I give a urine sample?

A nurse will give you an antiseptic wipe (to clean yourself) and a sterile urine collection cup. In the bathroom, wash your hands with soap and warm water first.

  • For women: use the antiseptic wipe to clean your vagina by wiping yourself from front to back three times before you urinate. Fold the wipe each time you use it, so that you are wiping with a clean part each time.

  • For men: use the antiseptic wipe to clean the head of your penis. If you're not circumcised, pull the foreskin back behind the head of the penis before you use the wipe. Move the wipe around the head of your penis before you urinate.

  • Start urinating in the toilet. About halfway through the urination, start catching the urine in the cup.

  • Wash your hands with soap and warm water.

  • Give the sample to the nurse. Someone will look at your urine under a microscope to see if it has blood in it.

What are some common causes of microscopic hematuria?

Here are some common causes of blood in the urine:

  • Urinary tract (bladder) infection

  • Swelling in the filtering system of the kidneys (this is called “glomerulonephritis”)

  • A stone in your bladder or in a kidney

  • A disease that runs in families, like cystic kidney disease

  • Some medicines

  • A blood disease, like sickle cell anemia

  • A tumor in your urinary tract (this may or may not be cancer)

What will my doctor do if I have microscopic hematuria?

If you have blood in your urine, your doctor will ask you some questions to find out what caused it. If the cause is clear, your doctor will probably treat you. Then your doctor will check your urine again to see if the blood is gone.

If the cause isn't clear, you may need to have more tests. You might have an ultrasound exam or an intravenous pyelogram (this is like an x-ray). These tests are usually done by a urologist. This kind of doctor has special training in urinary problems. The urologist may look into your urinary tract using a thin tube called an “endoscope.”

Remember that it is always important to find out the cause of blood in your urine.

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