Rectal Bleeding and Inflammatory Bowel Disease

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One of the many symptoms of inflammatory bowel disease (IBD) is bleeding. Blood in or on the stool can be frightening. While it can be a sign of an emergency, it's sometimes part of an IBD flare-up.

IBD is a term for two gastrointestinal conditions with chronic inflammation—ulcerative colitis and Crohn's disease. With either condition, blood might appear in or on the stool. Some people may pass no stool at all at times and just pass blood.

Bleeding from the rectum and large intestine from IBD is typically red or bright red. Blood coming from higher up in the digestive tract could appear as darker or black stools. In most cases, this bleeding is slow and steady.

This article discusses how bleeding may occur with ulcerative colitis and Crohn's disease. It covers symptoms to watch for and how it's usually treated.

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Bleeding in Ulcerative Colitis

Ulcerative colitis causes inflammation and sores called ulcers in the large intestine. Blood in the stool is more common in ulcerative colitis than it is in Crohn's disease.

The inflammation in ulcerative colitis often involves the rectum. Because the rectum is at the end of the large intestine, blood from this source is quite visible in or on the stool.

Bleeding also occurs with ulcerative colitis because this form of IBD attacks the lining (mucosa) of the large intestine. The ulcers that form in the mucosa of the large intestine tend to bleed.

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What Causes Ulcerative Colitis?

In some cases, bleeding from ulcerative colitis can lead to significant blood loss. The ultimate goal of treatment will be to calm the inflammation and stop the bleeding. Treating the loss of blood may also be necessary.

Blood loss from ulcerative colitis can cause anemia, which is a low red blood cell count. Mild cases of anemia can be treated by supplementing with iron, folic acid, and vitamin B12 to help form new blood cells. In more serious cases of blood loss, a blood transfusion to receive blood from a donor might be needed.

The most severe bleeding (called hemorrhaging) caused by ulcerative colitis could be life-threatening. This isn't common, but if the bleeding can't be stopped, surgery may be needed. This surgery involves removing the colon and creating an ileostomy, an opening in the abdomen for waste to exit.

During ileostomy surgery, the large intestine is removed. An opening, or stoma, is created so waste can pass outside the body into a bag worn on the abdomen.

Another surgery might be done at a later date to create a J-pouch. The J-pouch uses part of your small intestine to form a pouch to connect to the anal canal. This creates a way for you to pass stool the usual way, through the rectum, instead of through the stoma.

Bleeding in Crohn's Disease

Blood in the stool is less common with Crohn's disease than ulcerative colitis. However, this can vary based on where Crohn's disease is causing the inflammation.

Crohn's disease can cause inflammation in the small and large intestines. Crohn's disease that's found in the large intestine or rectum, rather than the small intestine, is more likely to cause blood in the stool.

Treating blood loss from Crohn's disease will be similar to that in ulcerative colitis:

  • Getting the IBD under control
  • Supplementing with vitamins
  • Blood transfusion, if necessary
  • Surgery, if necessary

With Crohn's disease, resection surgery may be done in order to remove the parts of the intestine that have been damaged by inflammation. J-pouch surgery isn't usually done for Crohn's disease because Crohn's may reappear in the pouch.

Blood loss can also occur with an anal fissure, which can develop as a complication of Crohn's disease. A fissure is a tear in the lining of the anal canal. Fissures are more common with Crohn's than they are with ulcerative colitis. In most cases, they can be treated successfully without surgery.

Recap

Crohn's disease may cause blood in the stool, either from inflammation or from anal fissures. Severe cases of inflammation may require resection surgery, which removes the damaged part of the intestines.

When to See a Doctor

Let your doctor know anytime you notice any blood in your stool. It should be discussed with a physician as soon as possible, especially if it hasn't happened in a while.

Call 911 when:

  • Bleeding is severe.
  • You're vomiting blood.
  • You faint or feel like you'll faint.

Summary

Ulcerative colitis and Crohn's disease, conditions that are types of IBD, can cause blood in the stool. Bleeding is more common in ulcerative colitis than Crohn's disease.

With ulcerative colitis, you may have inflammation around the rectum, which can cause visible blood in the stool. Ulcers in the colon may also lead to bleeding.

Crohn's disease can cause blood in the stool from inflammation in the colon or rectum. You may also have bleeding from anal fissures, which can be a complication of Crohn's.

Your doctor will work with you to help get your IBD symptoms, including bleeding, under control. Sometimes blood in the stool can lead to anemia, a low red blood cell count. If the bleeding is severe, you may need emergency treatment, including a blood transfusion or surgery to remove the damaged intestine.

A Word From Verywell

Bleeding from the rectum and having blood in or on the stool is not uncommon in IBD. It's one of the hallmark signs of ulcerative colitis because most patients do experience this sign.

Even so, bleeding should always be discussed with a gastroenterologist. It may mean something is going on with your IBD, and a change in therapy might be needed. Even if you've had bleeding before, it's important to talk it over with a doctor.

If you lose a lot of blood, you'll need immediate care. Call 911 if you have any symptoms such as fainting, dizziness, or severe pain.

2 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Ungaro R, Mehandru S, Allen PB, Peyrin-biroulet L, Colombel JF. Ulcerative colitis. Lancet. 2017;389(10080):1756-1770. doi:10.1016/S0140-6736(16)32126-2

  2. Gajendran M, Loganathan P, Catinella AP, Hashash JG. A comprehensive review and update on Crohn's disease. Dis Mon. 2018;64(2):20-57. doi:10.1016/j.disamonth.2017.07.001

Additional Reading
  • American Gastroenterological Association. "Inflammatory Bowel Disease." Gastro.org Apr 2008.

  • Crohns and Colitis Foundation of America. "What is Crohn’s Disease?." CCFA.org 2012. 

  • National Digestive Diseases Information Clearinghouse. "Crohn’s Disease." National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) Dec 2011.

By Amber J. Tresca
Amber J. Tresca is a freelance writer and speaker who covers digestive conditions, including IBD. She was diagnosed with ulcerative colitis at age 16.