Why Is There Blood in My Stool?

Noticing blood in your stool can be alarming. While it may be caused by a minor issue such as hemorrhoids, it can also be a sign of a more serious digestive condition. Understanding the possible causes of rectal bleeding can help determine when symptoms require medical attention.

Blood in stool may appear bright red, dark red, or even black, depending on where the bleeding originates in the digestive tract. In some cases, bleeding may occur only occasionally, while in others it may persist or worsen over time.

Because bleeding from the gastrointestinal tract—also known as GI bleeding—can have several potential causes, it is important to speak with a healthcare professional if you notice this symptom.

What Does Blood in Stool Look Like?

Blood in stool can appear in several different ways, and the color often provides clues about where the bleeding is occurring.

Some individuals notice bright red blood in stool, which may appear on the surface of the stool, in the toilet bowl, or on toilet paper after wiping. This type of bleeding typically comes from the lower digestive tract, such as the rectum or anus.

Other people may notice stool that appears dark, sticky, or tar-like. This is known as black, tarry stool and may indicate bleeding higher in the digestive tract, such as the stomach or upper small intestine.

Occasionally, bleeding may not be visible to the naked eye but may still be detected during medical testing. Because GI bleeding can occur for many different reasons, identifying the source is an important step in diagnosis.

Common Causes of Bright Red Blood

One of the most common rectal bleeding causes involves conditions affecting the lower part of the digestive tract.

Hemorrhoids bleeding is a frequent cause of bright red blood in stool. Hemorrhoids are swollen veins in the rectum or anus that may bleed during bowel movements, particularly if there is straining or constipation.

Another possible cause involves small tears in the lining of the anus. These tears are known as anal fissures, and anal fissure symptoms may include pain during bowel movements and small amounts of bright red blood on toilet paper.

Although these conditions are usually not serious, persistent bleeding should still be evaluated to rule out other potential causes.

Causes of Dark or Black Stools

When bleeding occurs higher in the digestive tract, the blood may change color as it moves through the intestines. This can result in stool that appears dark, sticky, or tar-like.

This condition is often described as black tarry stool and may indicate bleeding from the stomach, esophagus, or upper small intestine. Possible causes include stomach ulcers, gastritis, or other sources of GI bleeding.

Because black stool may signal significant bleeding within the digestive tract, it should always be evaluated by a healthcare professional.

Inflammatory Conditions That Cause Rectal Bleeding

Certain inflammatory digestive disorders can also cause rectal bleeding.

Inflammatory bowel disease (IBD), which includes Crohn’s disease and ulcerative colitis, can lead to chronic inflammation of the digestive tract. In these cases, IBD bleeding may occur along with symptoms such as abdominal pain, diarrhea, and fatigue.

Because inflammatory bowel diseases can damage the intestinal lining, bleeding may occur repeatedly during disease flare-ups. Patients experiencing symptoms consistent with IBD bleeding should seek evaluation by a gastroenterologist.

Could It Be Colorectal Cancer?

Although less common than conditions like hemorrhoids, bleeding in the stool can sometimes be associated with colorectal cancer.

Possible colon cancer symptoms include rectal bleeding, changes in bowel habits, unexplained weight loss, and persistent abdominal discomfort. In some cases, bleeding may be intermittent or difficult to notice.

Because colorectal cancer often develops slowly, early detection is important. Routine colonoscopy screening can help identify precancerous polyps or early-stage cancers before symptoms become severe.

When Blood in Stool Is an Emergency

In some situations, GI bleeding requires immediate medical attention.

Large amounts of blood in the stool, persistent bleeding, or symptoms such as dizziness, weakness, or fainting may indicate significant blood loss. These symptoms can suggest a more serious source of bleeding within the digestive tract.

Black, tar-like stools accompanied by abdominal pain or vomiting blood should also be considered a medical emergency.

If these symptoms occur, prompt evaluation in an emergency medical setting is recommended.

How a Gastroenterologist Diagnoses Rectal Bleeding

A gastroenterologist specializes in diagnosing and treating digestive conditions that may cause bleeding in the gastrointestinal tract.

During an evaluation, the doctor will review your medical history and symptoms, including how often bleeding occurs and whether you notice bright red blood in stool or darker stool.

They may also ask about other symptoms such as abdominal pain, fatigue, or changes in bowel habits that could suggest underlying rectal bleeding causes such as hemorrhoids, inflammatory conditions, or colon cancer symptoms.

A physical examination and additional testing may be recommended to determine the exact source of the bleeding.

What Tests Might Be Recommended?

To identify the source of GI bleeding, your doctor may recommend certain diagnostic tests.

Blood tests can help detect anemia, which may occur when bleeding has been ongoing. Stool tests may also be used to identify hidden blood that is not visible during bowel movements.

In many cases, colonoscopy screening is recommended to directly examine the colon and rectum. During a colonoscopy, a thin flexible camera is used to evaluate the lining of the digestive tract and identify potential causes of bleeding such as polyps, inflammation, or tumors.

These tests allow healthcare providers to determine the most appropriate treatment plan.

When To Talk to Your Doctor

If you notice blood in your stool, it is important to speak with the professionals at Allied Digestive Health especially if symptoms persist or worsen.

Even though many rectal bleeding causes—such as hemorrhoids bleeding or anal fissure symptoms—are relatively common and treatable, bleeding can sometimes indicate a more serious condition.

A gastroenterologist can evaluate potential causes of GI bleeding, recommend appropriate testing such as colonoscopy screening, and help determine the most effective treatment for your condition.