Rectal bleeding is generally a treatable condition; however, in rare cases, it may indicate a more serious health problem. Bleeding from the anus can result from various causes, ranging from hemorrhoids and anal fistulas to diverticular disease and, less commonly, colorectal cancer. For this reason, rectal bleeding should never be ignored, and the underlying cause must be evaluated promptly by a general surgery specialist.
What Is Rectal Bleeding?
Rectal bleeding refers to the presence of blood during or after a bowel movement, or blood seen on stool. It may appear on toilet paper, on the surface of the stool, or on underwear. The blood may be bright red, maroon, or dark (tar-like).
The color of the blood often provides clues about the source. Bright red blood typically indicates bleeding from the lower anal region (such as fissures or hemorrhoids). Dark or tarry blood mixed with the stool may suggest bleeding from higher up in the colon or small intestine.
What Causes Rectal Bleeding?
There are many possible answers to the question, “What causes rectal bleeding?” Several different conditions can lead to blood coming from the anus. The most common causes include:
Common Causes of Rectal Bleeding
- Constipation: Hard stools can tear the anal mucosa, causing an anal fissure. This often leads to sharp pain and bright red bleeding during bowel movements.
- Hemorrhoids: Swollen veins around the anus may bleed, usually causing painless, bright red blood.
- Anal Fissure: Small tears in the anal canal that cause “glass-cutting” pain and bleeding during defecation.
- Anal Fistula: An infected tunnel near the anus that may cause discharge and occasional bleeding.
- Colon Polyps: Benign growths in the colon that can sometimes bleed.
- Diverticular Disease: Inflamed pouches in the colon (diverticulitis) may lead to bleeding.
- Inflammatory Bowel Diseases (Ulcerative Colitis, Crohn’s Disease): Chronic inflammation can cause bloody stool, mucus, and diarrhea.
- Colorectal Cancer: Especially in older adults, unexplained rectal bleeding can be an early warning sign.
- Medications: Blood thinners, aspirin, and certain painkillers may increase bleeding.
What Are the Symptoms of Rectal Bleeding?
Rectal bleeding may occur alone or alongside other symptoms. The following signs require prompt medical evaluation:
- Frequent blood on stool or toilet paper
- Abdominal pain, diarrhea, or constipation
- Unintentional weight loss and loss of appetite
- Fatigue, dizziness, or palpitations
- Dark or black, tarry stool (melena)
- Anal pain, discharge, or swelling
How Is Rectal Bleeding Diagnosed?
To identify the bleeding source, a physical examination and endoscopic evaluation may be necessary. Common diagnostic tests include:
- Anoscopy or Proctoscopy: Direct examination of the anus and rectum
- Colonoscopy: Complete evaluation of the entire colon, with biopsy if needed
- Laboratory tests: Hemoglobin, stool occult blood test, and other blood work
How Is Rectal Bleeding Treated?
Treatment depends on the underlying cause:
- Hemorrhoids or Anal Fissures: Medications, diet changes, and managing constipation are usually sufficient.
- Advanced Hemorrhoids, Polyps, or Tumors: Endoscopic procedures or surgery may be required.
- If the bleeding is due to colorectal cancer: Early diagnosis is life-saving and allows timely treatment.
Self-medicating without knowing the cause of bleeding is strongly discouraged. Early evaluation ensures successful treatment of minor conditions and prevents progression of serious diseases.
What Happens If Rectal Bleeding Is Left Untreated?
Untreated causes of rectal bleeding may lead to more serious complications over time. Depending on the underlying condition, delayed diagnosis may increase the risk of developing colorectal, rectal, or—in rare cases—other abdominal cancers.
If rectal bleeding is accompanied by symptoms such as blood in stool, fatigue, abdominal pain, or unexplained weight loss, a doctor should be consulted immediately and treatment should begin without delay.
