Seeing blood after a bowel movement is alarming. Most of the time the cause is benign, but rectal bleeding is a symptom that should always be examined, never assumed.
What the color tells you
- Bright red, on the paper or dripping into the bowl: usually comes from the anus or rectum.
- Dark red or mixed with stool: suggests an origin higher in the colon.
- Black and tarry: points to the stomach or small intestine and needs prompt attention.
The 6 most common causes
- Hemorrhoids: painless bright-red bleeding. The most frequent cause.
- Anal fissure: a streak of blood with sharp pain when passing stool.
- Polyps: usually silent; they may bleed occasionally. Some become cancer over the years.
- Diverticular bleeding: sudden, painless and sometimes abundant.
- Inflammation: ulcerative colitis, Crohn’s disease or infections, with diarrhea and mucus.
- Colorectal cancer: the least common cause, and the one that cannot be missed.
When it is urgent
Go to an emergency department if the bleeding is heavy, if there are clots, if you feel dizzy or faint, or if it comes with severe abdominal pain.
How the cause is found
An exam and an anoscopy identify most anorectal causes in minutes. A colonoscopy is recommended when you are over 45, when there is a family history of colorectal cancer, when there is anemia or weight loss, or when the bleeding does not match what the exam shows.
The mistake to avoid
Treating yourself for hemorrhoids for months without being examined. If the bleeding repeats, get it checked once and know for certain.