The sudden appearance of blood clots in your stool is a symptom that requires immediate medical evaluation. The medical term for passing fresh blood through the rectum is hematochezia, and clotted blood signals that bleeding has occurred within the gastrointestinal (GI) tract. While causes range from minor issues to serious conditions, any instance of blood or blood clots in the stool indicates internal bleeding and necessitates a prompt diagnosis.
Understanding the Appearance of Clots and Blood Source
The formation of a blood clot within the stool is a result of blood pooling and initiating the body’s natural coagulation cascade within the digestive tract before it is expelled. This clotting process typically suggests a more substantial volume of bleeding compared to just streaks of blood. The color and consistency of the blood are crucial indicators that help determine the general location of the bleeding within the GI system.
Bright red blood or bright red clots generally point to a source in the lower GI tract, specifically the colon, rectum, or anus. Because the blood has traveled a relatively short distance, it remains fresh and has not been significantly altered by digestive enzymes or exposure to oxygen. Conversely, dark red or maroon clots, and particularly black, tarry, and sticky stools (known as melena), suggest bleeding higher up in the digestive tract, such as the stomach or small intestine. This darker color occurs because the hemoglobin in the blood has been chemically changed by digestive acids and bacteria over a longer transit time.
Common Causes Requiring Prompt, Non-Urgent Care
Many frequent causes of blood clots originate in the lower digestive tract and are generally not life-threatening, though they still require medical attention. Internal hemorrhoids are swollen veins inside the rectum prone to rupture, especially during straining. The blood from these ruptures can clot before passing, often appearing as bright red clots mixed with stool.
Anal fissures, small tears in the lining of the anus, also commonly cause bright red bleeding and occasional small clots. These tears often result from passing hard stools or chronic diarrhea, and the resulting blood is usually accompanied by sharp pain during or after a bowel movement. Mild cases of diverticulosis, where small pouches called diverticula form in the colon wall, can also lead to painless bleeding and subsequent clotting. A doctor’s examination is needed to confirm the diagnosis and rule out more serious issues.
Serious Underlying Conditions Requiring Immediate Attention
While some causes are less severe, blood clots can also signal conditions requiring immediate and more aggressive medical intervention. Inflammatory Bowel Disease (IBD), including Crohn’s disease and Ulcerative Colitis, causes chronic inflammation and ulceration of the GI lining. This damage leads to bloody diarrhea, often with mucus and clots, as the inflamed tissue bleeds readily.
Severe diverticular bleeding occurs when a small artery near a diverticulum ruptures, leading to a sudden, painless, and substantial volume of bright red or maroon blood and clots. Colorectal malignancy (cancer) and large non-cancerous polyps can also cause significant bleeding as they grow and erode the colon lining. Bleeding from these tumors is often intermittent and may result in clots, sometimes accompanied by a change in bowel habits or unexplained weight loss.
Certain “red flag” symptoms accompanying blood clots constitute a medical emergency requiring immediate attention. Signs of significant blood loss or hemodynamic instability include severe dizziness, fainting, a rapid or irregular heart rate, or a large volume of blood loss that fills the toilet bowl. These symptoms indicate a potentially life-threatening situation where the body is struggling to maintain adequate blood pressure and oxygen supply.
The Diagnostic Process and Medical Evaluation
A thorough medical evaluation is necessary to pinpoint the exact source of the bleeding. The initial consultation involves a detailed review of the patient’s medical history, including the blood’s color, frequency, and volume, and any associated symptoms like abdominal pain or changes in bowel habits. This is followed by a physical examination, which includes a digital rectal exam (DRE) to check for tenderness, masses, or bleeding in the lowest part of the rectum.
Laboratory tests, such as a complete blood count (CBC), help determine the degree of blood loss and whether anemia is present. Screening tests like the Fecal Occult Blood Test (FOBT) may confirm the presence of blood. The most common and definitive procedure for investigating lower GI bleeding is a colonoscopy, which uses a flexible tube with a camera to visually inspect the entire colon.
If a higher GI source is suspected due to darker blood or other symptoms, an upper endoscopy may be performed to examine the esophagus, stomach, and the beginning of the small intestine. For actively bleeding patients or when a colonoscopy is inconclusive, specialized imaging techniques like Computed Tomography Angiography (CTA) can be used to locate the site of bleeding. The diagnostic process moves systematically from less invasive to more targeted procedures until the precise cause is identified.