Finding blood in your stool warrants a discussion with a medical professional. While many instances stem from minor, non-threatening conditions, blood can also signal serious underlying issues within the gastrointestinal (GI) tract. Since symptoms alone cannot determine the cause, you should always seek medical advice. A healthcare provider is the only one who can accurately diagnose the source and recommend the appropriate next steps.
Interpreting the Color and Consistency
The appearance of blood in your stool provides important clues about where the bleeding is originating in the digestive system. The blood’s color changes depending on how long it has been exposed to digestive enzymes and acids.
Bright red blood (hematochezia) typically suggests bleeding from the lower GI tract, such as the rectum, anus, or lower colon. Since the blood has traveled a short distance, it remains fresh and undigested, maintaining its vibrant color. Bleeding from conditions like hemorrhoids or anal fissures usually presents this way.
Dark red or maroon blood often indicates bleeding higher up in the colon or in the small intestine. This darker color results from the blood mixing with stool and partially undergoing digestion as it moves through the large intestine.
Black, tarry, and foul-smelling stools (melena) are a sign of bleeding higher up in the digestive tract, typically the stomach or duodenum. The black color is caused by hemoglobin reacting with digestive acids and enzymes, turning the blood into a dark, sticky substance. Melena requires approximately 100 to 200 milliliters of blood in the upper GI tract and can persist for several days after the bleeding has stopped.
Common Causes That Are Not Emergencies
Many frequent causes of blood in the stool are benign and not medical emergencies, though they still require medical evaluation. These generally present as bright red blood, indicating a source near the exit of the GI tract.
Hemorrhoids are the most common cause of bright red blood, resulting from swollen veins in the rectum or anus. Straining during bowel movements or increased pressure, such as during pregnancy, can cause these vessels to become irritated and bleed. The blood usually appears on the toilet paper or as streaks on the surface of the stool.
Anal fissures are small tears in the lining of the anal canal, often caused by passing hard or large stools. These tears can be painful during a bowel movement and cause small amounts of bright red blood. Both hemorrhoids and fissures are manageable with dietary changes to soften the stool, such as increasing fiber and water intake.
Certain foods and supplements can mimic the appearance of blood, potentially causing unnecessary alarm. Consuming large amounts of foods with red or purple pigments, such as beets or red food coloring, can temporarily change stool color. Iron supplements or medications containing bismuth can also lead to stools that appear very dark or black, which should not be mistaken for melena.
Immediate Warning Signs and Serious Conditions
While many causes are minor, recognizing symptoms that indicate a serious medical condition or acute emergency is important. Certain accompanying symptoms require immediate medical attention, such as visiting an emergency department.
Immediate warning signs include symptoms of significant blood loss or shock, such as dizziness, fainting, rapid heartbeat, and extreme fatigue. Seek emergency care if you notice a large amount of blood or blood clots, if the bleeding is severe and persistent, or if you experience severe, unexplained abdominal pain, fever, or vomiting blood (hematemesis) along with blood in the stool.
A variety of serious conditions necessitate prompt diagnosis and treatment. Diverticular disease involves small pouches (diverticula) that form in the colon wall and can cause significant, acute bleeding. Inflammatory Bowel Disease (IBD), including Crohn’s disease and ulcerative colitis, causes chronic inflammation and ulcers, leading to bloody diarrhea, abdominal cramps, and unexplained weight loss.
Bleeding can also originate from the upper GI tract, such as from peptic ulcers in the stomach or duodenum, often presenting as black, tarry melena. Colorectal cancer is a serious, though less common, cause of bleeding, particularly in older adults. Tumors can bleed slowly, causing occult (hidden) blood not visible to the naked eye, or they can cause visible bright red or dark blood depending on location.
Diagnostic Procedures and Medical Next Steps
Once you seek medical care, the healthcare provider will begin a process to pinpoint the source of the bleeding. The initial consultation focuses on a detailed medical history, including questions about the blood’s color, frequency, and consistency, as well as any associated symptoms like pain or weight loss.
A physical examination, often including a digital rectal exam, helps the doctor check for obvious, low-lying sources of bleeding such as hemorrhoids or fissures. Initial laboratory tests may include a complete blood count to check for anemia (a sign of chronic blood loss) and a stool test for occult blood.
To visualize the GI tract, a doctor may recommend an endoscopy, which involves inserting a long, flexible tube with a camera. An upper endoscopy examines the esophagus, stomach, and duodenum, while a colonoscopy views the entire large intestine and rectum. These procedures allow the doctor to locate the exact site of bleeding, take tissue samples (biopsies), and sometimes treat the bleeding directly.
If the bleeding source is not found in the upper or lower GI tract, specialized procedures like capsule endoscopy may be used to examine the small intestine. The specific treatment plan depends entirely on the diagnosis, ranging from simple dietary adjustments for minor causes to medication for IBD or surgical intervention for more complex conditions.