Is every blood in the stool a hemorrhoid?

Seeing blood on the toilet paper or in the toilet bowl is frightening. Most people immediately tell themselves “it must be hemorrhoids”, and sometimes that thought makes them put off follow-up for months. The short answer is: hemorrhoids are the most common cause, but not the only one. And you cannot tell from the blood itself which it is.

What can cause bleeding?

• Internal hemorrhoids: bright red blood, usually painless, during or after a bowel movement. ASCRS says it can even be heavy.
• Anal fissure (a tear): sharp pain when passing stool and bright red blood on the paper or the stool (NHS and ASCRS). ASCRS says fissures and hemorrhoids are often mistaken for each other.
• Diverticula and diverticulitis: a little or a lot of blood with the stool, and sometimes lower abdominal pain. ASCRS also recognizes heavy diverticular bleeding.
• Inflammatory bowel disease (ulcerative colitis, Crohn’s disease): bloody diarrhea, cramps, fever, weight loss (ASCRS).
• Polyps: most polyps cause no symptoms, but larger ones can cause blood, mucus or a change in bowel habit (ASCRS).
• Colon or rectal cancer: ASCRS says blood in the stool may be a sign of rectal cancer and is often mistaken for hemorrhoids.
• Abscess and fistula: mostly with pain and discharge, but sometimes blood too.

What does the color of the blood tell you?

Color is a clue, not a diagnosis. For internal hemorrhoids ASCRS considers bright red blood common, but the same source also lists “bright red or very dark” blood among the symptoms of colon cancer. The NHS also says blood in the stool may look “red or black”, and if the stool is black or dark red or you have bloody diarrhea, you should book an urgent appointment. So color cannot tell you with certainty where the source is.

Why shouldn’t we just guess?

ASCRS says that with hemorrhoids, more serious conditions such as cancer need to be ruled out, and when there is bleeding the doctor “may want to look higher up too”. For this a sigmoidoscopy (about half of the colon) or a colonoscopy (usually the whole colon) is used. For fissures, ASCRS says a fissure does not cause colon cancer, but lasting symptoms still need assessment and a colonoscopy may be needed.

For bowel cancer the NHS says the symptoms (a change in bowel habit, blood in the stool, a constant urge to go, abdominal pain or bloating, a lump, weight loss, anemia and tiredness) are very common, have other causes, and having them certainly does not mean cancer, but they need to be seen.

Who should go sooner?

Do not delay assessment if:

• The bleeding is new or repeated, especially without pain
• It comes with a change in bowel habit, thinner stools, unexplained weight loss, or tiredness and anemia
• Someone in the family has had bowel cancer or polyps, or you have inflammatory bowel disease
• Simple treatment for hemorrhoids or a fissure has not worked after about a week (NIDDK uses one week for hemorrhoids; the NHS uses 7 days for a fissure)

When it is an emergency

• Bleeding that will not stop, a lot of blood or large clots (NHS: 999 or emergency services; in Iran, 115)
• Bleeding with weakness, dizziness, paleness or fainting
• Severe abdominal pain with fever
• Severe anal pain with fever

See “When should I call urgently?” for the full list.

What is the visit like?

The examination usually includes a conversation, looking at the area and, in most cases, a finger examination; ASCRS names this for a change in bowel habit or bleeding. Sometimes a colonoscopy is needed. Read the guide “The first visit and examination” to know what to expect.

A simple summary

• Blood in the stool has different causes and most of them can be treated.
• Hemorrhoids are common but should not be assumed without an examination.
• If the bleeding is new or repeated, comes with another symptom, or you have a family history, book an appointment.
• Heavy bleeding or bleeding that will not stop is an emergency.

This article does not replace an examination; ask your doctor about your own situation.