Overview: What does rectal bleeding look like?
Bleeding is the immediate and most apparent sign of rectal bleeding. The blood may be visible in the stool, toilet bowl, or toilet paper. Sometimes the blood will leak out of the anus unrelated to bowel movement. Rectal bleeding can be alarming and unexpected, especially if the blood is bright red. It means that bleeding is occurring inside the digestive system. But from where? What’s causing it? Is it bad? These are legitimate worries without obvious answers.
As to what is bleeding, the appearance of the blood is a clue. Bright red blood means that the blood originates near the rectum: the anal canal, the rectum, or the large intestine right above the rectum. If the blood is maroon-colored, it originates further from the rectum. Black and tarry stools mean the blood originates further up the GI tract: the esophagus, stomach, or the first part of the small intestine. There may be other symptoms, like pain, that narrow down the cause. However, it’s difficult to determine how bad the bleeding is. To answer these questions—what is bleeding, why it is, and how bad it is— see a healthcare professional for a diagnosis.
What causes rectal bleeding?
Rectal bleeding can appear bright red, maroon, or dark, depending on where the bleeding starts. The causes of black and tarry stools can be found here. Rectal bleeding causes include:
The most common cause of rectal bleeding is hemorrhoids. When rectal veins fill with blood (from constipation, straining with bowel movements, or during pregnancy) hemorrhoids can result. Sometimes they swell and bleed. Internal hemorrhoids are painless, but external hemorrhoids that protrude from the anus are often painful.
The second most common cause of rectal bleeding is anal fissures. An anal fissure is a small tear in the anal lining. Its signature symptom is sharp pain when making bowel movements that can last hours after a bowel movement due to sphincter spasms.
Colorectal cancer is malignant growths in the colon or rectum. Anal cancer involves malignant tumorous growths on the anal lining. These tumors grow blood vessels for their blood supply. Tumor blood vessels are fragile and easily broken. Rectal bleeding with cancers often happens as the cancer outgrows its blood supply. Other symptoms of colorectal cancer include thinner-caliber stools, abdominal pain, constipation, and unintentional weight loss. HPV vaccines can decrease the risk of rectal cancer. Colonoscopies help remove benign colon polyps before they change into cancer.
Polyps are noncancerous growths on the lining of the colon. Though usually small, large polyps are easily damaged and can bleed into the colon. Polyps normally don’t have symptoms.
Inflammatory bowel disease sometimes causes bleeding along with other symptoms such as diarrhea, abdominal pain, cramping, and fever.
Sometimes people form small pouches called diverticula in their colon. The blood vessels in these pouches can be fragile and easily broken. Diverticula (outpouchings of the bowel wall) are asymptomatic, but can become inflamed and cause left lower quadrant abdominal pain and fever.
Sexually transmitted diseases, E. coli, C. difficile, and other intestinal infections, can sometimes cause bleeding due to swelling.
A hole in the anus caused by an abscess, infection, or inflammatory bowel disease. A fisula is an abnormal tract occurring between two things like a tract between the bowel and the bladder or the bowel and the skin.
Swelling of the rectum due to infections, trauma, or other causes.
Swelling of the anal lining usually causes itching and burning around and in the anus. They can be damaged easily during bowel movements, particularly when passing hard stools. Food reactions are the most common cause of anal swelling.
Blood vessel abnormalities that can occur anywhere, including the colon or rectum, are called angiodysplasias. The malformed veins and arteries are easily damaged.
RELATED: What causes black stool? Related conditions and treatments
Should I be worried about rectal bleeding?
All gastrointestinal bleeding should be investigated and treated. If a diagnosis and treatment are started and bleeding continues, then further investigation is needed. Rectal bleeding may be due to a relatively harmless cause such as a swollen hemorrhoid, anal fissure, or colon polyps. It could also be due to a serious condition such as cancer or infection. Rectal bleeding could be scant and temporary. However, it could be continuous or involve a lot of blood, both of which are medical emergencies.
Pay attention to the bleeding and other symptoms. Keep a bleeding journal: what caused it (hard stool or diarrhea), how often, how much blood, what treatment has been tried. If the bleeding is minor and goes away without any other symptoms, it’s probably not serious. If you keep noticing blood or there are other symptoms like abdominal pain, fever, constipation, diarrhea, thin stools, or fatigue, talk to a healthcare professional. It’s not possible to know what’s causing the bleeding until it’s diagnosed. If you are symptomatic (dizzy, chest pain, difficulty breathing, there’s a lot of bleeding or continuous bleeding, go to the emergency room.
The most serious complication of rectal bleeding is blood loss. When blood loss is serious, symptoms include low blood pressure, fast heart rate, lightheadedness, and losing consciousness when it’s very bad. These are all signs that emergent treatment is required.
How is the cause of rectal bleeding diagnosed?
Finding the cause of rectal bleeding involves some diagnostic work. The first goal of the clinician is to make sure the patient is hemodynamically stable by taking vital signs. A thorough medical history is required. The clinician may ask questions like:
When did the blood first appear?
Have you had rectal bleeding before?
Do you have other symptoms?
Do you have any medical conditions?
Do you have a family history of rectal bleeding, rectal pain, gastrointestinal problems, polyps, or cancer?
Any previous abdominal surgeries?
Any rectal instrumentation?
What drugs are you taking?
The clinician will perform an abdominal exam and carefully examine the anus. A thorough exam includes looking at the outside of the anus and examining inside the anus a few inches with anoscopy.
Both hemorrhoids and anal fissures are easily diagnosed, but further work may be needed to identify other (possibly simultaneous) causes. Blood tests, a colonoscopy, a fecal occult blood test, or CT scans may be used to find other causes.
How long does rectal bleeding last?
Rectal bleeding will last as long as bleeding in the colon, rectum, or anal canal occurs. The good news is that rectal bleeding doesn’t last long in most cases. People with hemorrhoids or an anal fissure may notice minor rectal bleeding for a few days or weeks until the problem resolves. Other causes of rectal bleeding, such as inflammatory bowel disease or cancer, may cause repeated episodes of rectal bleeding.
How to stop rectal bleeding
80% of lower gastrointestinal bleeding and 95% of rectal bleeding last a short time and then go away. Unfortunately, sometimes the bleeding lasts longer. In those cases, the most cautious thing to do is to see a healthcare provider.
Rectal bleeding treatments focus on the underlying cause. The bleeding itself will not be an issue unless there’s notable blood loss or the likelihood of continued blood loss. These are life-threatening emergencies and will be handled in an emergency room or ICU. If this is truly an emergency, call 911. EMTs can assess vital signs, insert a venous line, give intravenous fluids all while speeding to the emergency department.
The most common causes of rectal bleeding are hemorrhoids and anal fissures. Anal fissures are initially treated conservatively with fiber, fluids, stool softeners, warm baths after defecation (to let the anal spasm relax), and maintaining regular bowel habits. Hemorrhoids rarely are removed during the office visit, but it’s more common to be sent home to take care of the problem with fiber, fluids, and warm baths.
Treatments for other causes such as inflammatory bowel disease, infections, diverticulosis, or cancer are usually treated by a gastroenterologist and may include more involved and lengthy care. They’ll involve prescription drugs and sometimes require surgery.
FAQs about the causes of rectal bleeding
Is rectal bleeding cancerous?
Rectal bleeding can be caused by a cancerous tumor in the colon, rectum, or anus. Tumors grow their own arteries and veins, but these newly-grown blood vessels are easy to break. The tumor also sticks out into the colon or anus, so it’s easily damaged by stools as they go by. Cancer, however, is only one of many possible causes of rectal bleeding. People with colorectal cancer will usually notice other symptoms as well, including abdominal pain, constipation, fever, and long, narrow stools.
RELATED: Colon cancer symptoms: what are the early signs of colon cancer?
What medications cause rectal bleeding?
Medication side effects are not a common cause of rectal bleeding. Long-term use of NSAIDs like aspirin or ibuprofen can cause gastrointestinal bleeding, due to damage to the stomach or duodenum. Blood thinners don’t cause gastrointestinal bleeding, but if bleeding does start in the colon or rectum, blood thinners cause brisker blood loss because the body is unable to make a blood clot.
Is blood from an upper or lower GI bleed?
Red or maroon-colored blood in the stool is caused by bleeding in the lower gastrointestinal tract. The closer the bleeding is to the anus, the redder the blood will appear. Bleeding in the upper GI tract gets exposed to stomach acid, which turns blood black. Upper digestive tract bleeding appears as black, tarry, and smelly stools.
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