Top 5 Reasons for Rectal Bleeding

Top 5 Reasons for Rectal Bleeding
Top 5 Reasons for Rectal Bleeding.

“Oh no! There is blood in the toilet!” That is one of the most common reasons patients come to me and are alarmed.

First, all bleeding is abnormal and needs to be addressed. Even a little bit of blood can look really dramatic. Fortunately, most cases of rectal bleeding are not a big deal and are treatable. Rectal bleeding, which is termed as ‘hematochezia’ medically, is one of the most common reasons people see a gastroenterologist.

In this article, I want to address the five main causes of rectal bleeding: hemorrhoids, anal fissures, colitis, polyps and least likely cancer.


Hemorrhoids are one of the most common reasons for rectal bleeding. Hemorrhoids are a collection of blood vessels at the anus and are actually a normal part of our anatomy. They function like shock absorbers when we defecate. The hemorrhoids can swell when we strain, and if enough pressure builds up, they will bleed.

We have internal and external hemorrhoids, and both can bleed. The main difference is the external ones tend to hurt while the internal ones tend to cause more bleeding and itching. Most hemorrhoids can be treated conservatively with improving constipation and avoiding straining.  If this doesn’t work, then your doctor will need to discuss treatment options.

Anal Fissure

Anal fissures are another cause of bleeding that gets mistaken for hemorrhoids.

A fissure is a cut or a tear in the anus, and typically is very painful. People who have an anal fissure describe a scratching sensation when they defecate. Anal Fissures may occur in people with chronic constipation, any hard passage of stool, and are associated with Crohn’s Disease as well. Treatment is usually fiber and/or creams, and if this doesn’t work then surgical repair may be needed.


Colitis is inflammation of the lining of the colon. The types of bleeding from colitis can vary. The difference between this type of bleeding as opposed to other types of bleeding is that bleeding from colitis is usually accompanied with pain and diarrhea. There are numerous causes of colitis including; infection, inflammatory bowel disease, and ischemic colitis. Since the definition is just inflammation, the type of bleeding can vary significantly depending on the cause.

For instance, if the colitis is due to a serious condition like inflammatory bowel disease, there can be a large amount of blood, which can result in serious health problems. Any type of colitis is very serious and needs to be addressed with your health care professional immediately.

Colon Polyps 

A polyp is a small clump of cells or an abnormal growth of tissue found on the lining of the colon. Only a small proportion of polyps cause symptoms or signs, but occasionally a large polyp can bleed. This type of bleeding may be bright red, dark or can be mixed in with the stool. The key here is that most polyps don’t bleed, so you can have polyps and not even know it. Colon cancer develops from colon polyps, so this is why all people need to have a colonoscopy at age 50 or sooner.

Colorectal Cancer

Colon cancer is the most dangerous, yet is the least common cause of rectal bleeding. That being said, the problem with colon cancer is that it can mimic all the above types of bleeding. As the cancer grows, it can cause change in stool caliber, altered bowel habits, pain and bleeding. The cancer may arise in its early stages in the form of polyps, which may remain asymptomatic for years. That is why it is recommended for all people age 50 to get a colonoscopy, and anyone with a family history to have one at age 40. If there is rectal bleeding with weight loss, or anemia, this needs to be discussed immediately by a Gastroenterologist.

So, if you see blood in the toilet, although it can look really dramatic, don’t panic! Rectal bleeding is very common and most likely something benign and easy to treat. That being said, rectal bleeding is never normal so be sure to make an appointment with your healthcare professional at the first sign of bleeding.

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