What Causes Blood in Urine and Stool?

It's important that you talk with your doctor if you notice blood in your urine or stool.
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Few things are more alarming than spotting blood in your stool or urine. Though some causes are more easily remedied than others, it's always important to contact your doctor and find out the source so it can be treated.


Causes of Blood in Urine

The technical name for blood in urine is hematuria, according to the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). "Gross" hematuria is when the blood is clearly visible to the eye. It actually doesn't take much blood for you to notice the color of your urine is off. Just a few drops can stain otherwise clear urine pink, red or brown.


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The other is type is called "microscopic" hematuria, with amounts so low that it's only picked up when your urine is specifically tested and examined under a microscope.

In both instances, any number of causes could be to blame. They include:

  • bladder, kidney or prostate infection
  • trauma
  • vigorous exercise
  • a viral illness
  • sex
  • menstruation
  • endometriosis, a condition in which the lining of the uterus starts to grow outside the organ, according to the NIDDK


Some underlying causes are of particular concern, per the NIDDK. They include:

  • cancer of the bladder or kidney
  • inflammation of the kidney, urethra, bladder or prostate
  • hemophilia, a blood-clotting disorder
  • sickle cell disease, in which red blood cells are abnormally shaped
  • polycystic kidney disease, a genetic disorder that can cause cysts to grown on the kidneys



It’s impossible to know the severity of the underlying cause of bleeding in your urine, stool or both on your own. "Anytime someone sees blood in [the toilet], they should notify their physician," Dr. Chan says.

Causes of Blood in Stool

When blood makes its way into poop, it may actually turn the stool black or tarry, rather than red or pink, per the NIDDK. Once again, there are many potential causes, from very common to more rare.

"Blood in bowel movements is often caused by hemorrhoids," says Andrew Chan, MD, MPH, director of the Gastroenterology Training Program and the vice chair of gastroenterology at Massachusetts General Hospital and a professor of medicine at Harvard Medical School in Boston.


Hemorrhoids are inflamed or swollen veins located around the anus or lower rectum that can be either internal or external, according to the NIDDK. Internal hemorrhoids in particular are known to trigger rectal bleeding when a patient struggles with constipation and strains when on the toilet. Hemorrhoids can also trigger small tears called anal fissures, which can also lead to blood in stool.


Another relatively common condition that can lead to bleeding is a peptic ulcer, which can be prompted either by a bacterial infection or by overuse of non-steroidal anti-inflammatory pain medications. Regardless of how ulcers develop, GI bleeding can result, according to the NIDDK.


Many other gastrointestinal diseases can cause bleeding, such as ulcerative colitis, an inflammatory bowel disease, and severe and persistent reflux if it damages the esophagus, per the NIDDK. When the inflammation is in the stomach lining, it's called gastritis. It can be brought on by the same bacteria or pain medications that lead to stomach ulcers. For some people, excessive drinking or even stress can be the trigger, according to the Mayo Clinic.

"Another cause can be bleeding from diverticula," Dr. Chan says. These are small pouches that develop along the colon over time. The condition is called diverticulosis, and when one or more pouches get inflamed, it progresses to diverticulitis. Episodes of diverticulitis can be quite severe and necessitate immediate medical attention.


Most seriously, blood in the stool can be a sign of polyps or cancer, Dr. Chan says. Note that a tumor doesn't need to be cancerous to cause bleeding. When any type of tumor forms in the stomach, esophagus, colon or rectum, it tends to weaken the gastrointestinal tract, which can lead to bleeding.




Is this an emergency? If you are experiencing serious medical symptoms, please see the National Library of Medicine’s list of signs you need emergency medical attention or call 911.

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