If you notice blood in your stool, it may have originated from anywhere in the gastrointestinal tract, most often in the colon, rectum, or anus. The color of the blood may indicate the possible origin of the bleeding. Lesions close to the anus leak bright blood. The upper parts of the large intestine cause dark red or maroon blood. Bleeding from the stomach produces black and tarry stools called melena. If blood loss is severe, it may occur with the additional symptoms of weakness, dizziness, low blood pressure and anemia – which may require hospitalization. In some cases, you may have rectal bleeding that you are unable to see (fecal occult blood, or hidden blood), which can only be detected when stool samples are examined at a laboratory.

Causes of rectal bleeding

Rectal bleeding occurs for different reasons and certain causes are more prevalent at different ages.

Common causes of rectal bleeding include:

  • Abnormalities of Gut – most of these occur in young children and involve the lining of the gut. Examples include a twisting of the gut (volvulus), blockage due to one part of the gut being sucked into another (intussusception), and a congenital bulge in the small intestine (Meckel’s diverticulum).
  • Anal fissures – small tears in the anal canal lining, due to chronic constipation, diarrhea, straining, or anal intercourse.
  • Constipation and hard stools – constipation itself can occur for a variety of reasons such as a side effect of certain medications and is more common among older adults.
  • Hemorrhoids – swollen and inflamed veins in the anus or rectum caused by constipation, diarrhea, a low-fiber diet, heavy lifting, or hard stools.

Less common causes of rectal bleeding include cancer, colitiscolon polypsCrohn’s diseasediverticulosis, infections, and ulcers.

When to seek medical help

At some point in our lives, most people may notice a little blood in their stool. How do you know if it’s medically significant?

If you notice mild bleeding with your stool that lasts for more than a few days, schedule an appointment with your doctor for a proper assessment. Don’t dismiss it or assume the cause is minor if you otherwise feel healthy. That said, no matter your precise symptoms, if you are worried, you should see a doctor who specializes in disorders of the gastrointestinal tract to at the very least arm you with information for what signs and symptoms you need to be concerned with, given your health history and risks for various diseases.

On the other end of the spectrum, there are instances where blood in the stool indicates a medical emergency. Seek emergency medical assistance if you are experiencing significant amounts of rectal blooding – especially if it is also accompanied by severe abdominal pain or cramping and the following signs and symptoms of shock: fast, shallow breathing; vertigo; fuzzy vision; loss of consciousness; disorientation or confusion; nausea or vomiting; cold, damp, pale skin.

Diagnosing the cause of rectal bleeding

Because blood in the stool can indicate any number of problems, your doctor will need detailed information to help with an accurate diagnosis and treatment plan.

If the condition is chronic, it is helpful to keep a journal of your symptoms. When you meet your doctor, be prepared to provide the following information:

  • How long you’ve noticed rectal bleeding
  • Describe the color of the blood: is it a bright or dark red?
  • Whether the bleeding happens all the time, or whether it’s intermittent
  • If pain is involved, where in the body it is felt (such as the anus or stomach), when it occurs (such as while passing stool, or before or after passing stool) and how it feels (whether a burning, stabbing, itchiness, etc.)
  • Whether diarrhea or constipation is also occurring
  • If you have a family history of gastrointestinal disorders or bleeding
  • What medications you’re currently taking, including NSAIDs and blood-thinners
  • If you’re experiencing any unexplained weight loss

During the examination, the doctor will examine your anus and rectum by inserting a gloved finger or proctoscope into your anus to look inside. Anal fissures or hemorrhoids may be diagnosed this way. Additional tests may be needed to rule out other conditions.

For more information about common signs and symptoms of gastrointestinal disorders, schedule an appointment with one of our physicians by calling US Digestive Health at (717) 245-2228. Our board-certified physicians can offer expert help in the diagnosis and treatment of many different GI disorders.