The sudden sight of blood associated with a bowel movement or even passing gas can cause significant alarm. This symptom indicates bleeding somewhere in the gastrointestinal tract. While the discovery is understandably concerning, it is a relatively common occurrence that can be caused by a range of conditions. Regardless of the amount or frequency, any instance of rectal bleeding requires a prompt medical evaluation to determine the precise cause and ensure appropriate care.
Characteristics and Appearance of the Bleeding
The visual characteristics of the blood often offer initial clues about the location of the bleeding within the digestive system. Bright red blood typically indicates a source in the lower part of the gastrointestinal tract, such as the rectum or anus, because the blood has not traveled far. Seeing only a trace amount, like a streak on toilet paper or a few drops in the toilet bowl, is common with sources very close to the anal opening.
Conversely, blood that appears dark red or maroon suggests the bleeding is occurring higher up in the colon or small intestine. This darker color results from the blood being partially digested as it passes through the bowel. Melena, which is black, sticky, and tarry stool, usually signals bleeding much higher up in the stomach or upper small intestine. While the color provides a general guide, it is not a definitive diagnostic tool.
Common Sources of Minor Rectal Bleeding
The most frequent causes of minor rectal bleeding are typically benign conditions affecting the anal canal. Hemorrhoids, which are swollen veins inside the rectum or under the skin around the anus, are the most common source. Straining during a bowel movement can irritate the fragile surface of an internal hemorrhoid, causing it to bleed. This bleeding is often painless and presents as bright red blood coating the stool or dripping into the toilet bowl.
Anal fissures are another common cause, involving a small tear in the lining of the anal canal. The passage of hard stool can create this tear, which often results in sharp pain during a bowel movement, followed by bright red blood. The tear can be aggravated by the friction of passing gas, which may push residual blood out of the anus. These minor conditions are highly prevalent and often respond well to simple changes like increasing dietary fiber and fluid intake.
Conditions Requiring Urgent Medical Evaluation
While minor causes are most common, other serious conditions must be ruled out. Inflammatory Bowel Disease (IBD), which includes ulcerative colitis and Crohn’s disease, causes chronic inflammation of the digestive tract lining. Ulcerative colitis affects the colon and rectum, frequently leading to bloody diarrhea, abdominal cramping, and an urgent need to have a bowel movement. Crohn’s disease can affect any part of the digestive tract but also commonly presents with bleeding, pain, and weight loss.
Diverticular disease involves the formation of small, bulging pouches, called diverticula, in the lining of the large intestine. These pouches can sometimes bleed profusely when a small blood vessel next to the pouch ruptures, known as diverticular bleeding. This bleeding is often painless and can be a significant volume of dark or bright red blood.
Colorectal polyps are growths on the lining of the colon or rectum that can bleed easily and painlessly, and may be a precursor to cancer. Colorectal cancer is a serious cause of rectal bleeding, especially in people over the age of 45. Bleeding from a cancerous tumor can be intermittent and may be accompanied by a persistent change in bowel habits or unexplained weight loss. Early detection through medical evaluation is paramount for the best possible outcome.
Necessary Diagnostic Steps and Treatment
Any episode of rectal bleeding should prompt a visit to a physician, but certain signs necessitate immediate emergency care. These include passing a large volume of blood, experiencing severe abdominal pain, or having symptoms of significant blood loss such as dizziness, weakness, or a rapid heart rate.
For non-urgent but persistent bleeding, the diagnostic process typically begins with a physical examination, including a digital rectal exam and often an anoscopy. An anoscopy uses a small, lighted tube to view the anal canal. A stool test may be used to check for occult, or hidden, blood.
To investigate the colon, a physician may recommend a flexible sigmoidoscopy, which examines the rectum and the lower part of the colon. The most comprehensive test is a colonoscopy, which allows the physician to view the entire large intestine and is the standard procedure to identify polyps, IBD, or potential cancerous lesions. Treatment is then tailored directly to the underlying cause identified during the diagnostic workup.
Minor conditions like hemorrhoids and fissures are often managed with dietary changes to soften stools, such as increasing fiber and water intake, along with topical creams or sitz baths. More persistent hemorrhoids may require in-office procedures like rubber band ligation. Serious underlying conditions, such as IBD or colorectal cancer, require specific medical or surgical interventions.