Proctosigmoiditis is a type of ulcerative colitis that involves inflammation in the large intestine. However, multiple factors can affect proctosigmoiditis.

Ulcerative colitis is a condition where unusual reactions from the immune system cause inflammation and ulcers in the lining of the large intestine.

It is a chronic condition that may begin gradually and worsen over time.

This article discusses possible causes, risk factors, and treatments of proctosigmoiditis.

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Proctosigmoiditis is a form of ulcerative colitis (UC), an inflammatory bowel disease. Symptoms are due to inflammation in the large intestines.

This type of UC typically affects the rectum and the lower segment of the colon just above the rectum, known as the sigmoid colon.

Symptoms of proctosigmoiditis include:

  • weight loss
  • loss of appetite
  • pain in the left side of the abdomen
  • bloody diarrhea

Read more about inflammatory bowel disease.

It is unclear exactly what causes the inflammation from proctosigmoiditis, but several factors may play a role.

For example, an overactive immune system can lead to UC. Certain strains of bacteria may instigate the immune system to attack the large intestine in some people. This triggers inflammation and may lead to symptoms of proctosigmoiditis.

UC also tends to run in families, so a person’s genes are another possible reason why proctosigmoiditis may develop.

Other factors that can increase the risk of proctosigmoiditis include:

Learn about UC and genetics.

While there is no cure for the condition, it is possible to manage the symptoms. Treatments for proctosigmoiditis typically include medication, surgery, or a combination of both.


To control symptoms and prevent serious complications, most people who have proctosigmoiditis will need to take medication for their lifetime.

Medications help reduce the symptoms of proctosigmoiditis, prevent serious complications, and improve quality of life.

There are five types of medications that doctors may prescribe:

  • Aminosalicylates: These are anti-inflammatory drugs, such as mesalamine. They come in both topical and oral forms. Unless symptoms are extensive when a healthcare professional initially diagnoses the condition, people usually try topical forms first. Typically, these are the first type of medication prescribed for proctosigmoiditis.
  • Corticosteroids: Doctors may also prescribe these medications in either topical or oral forms to treat or prevent inflammation if necessary.
  • Immunomodulators: This is a class of drugs that reduces the activity of the immune system, such as methotrexate. Immunomodulators are only necessary if other medications are not working.
  • Biologics: These are a newer class of drugs that target tumor necrosis factor (TNF), a protein involved in inflammation. Examples of biologics include golimumab and infliximab.
  • Other medications: Occasionally, doctors may have to prescribe different medications to manage specific symptoms or complications, such as antibiotics for treating infections.

Learn more about treatments for UC.


In more severe cases of proctosigmoiditis, bowel surgery is an option. This may involve entirely removing the last portion of the colon (large intestine) and the rectum or the large intestine.

Learn more about surgery for UC.

Lifestyle changes

Lifestyle changes can also help people with proctosigmoiditis. These can include:

  • taking regular exercise
  • keeping a healthful diet
  • avoiding tobacco smoking
  • trying to reduce stress where possible

Learn what foods to eat and avoid with UC.

People with proctosigmoiditis could experience complications that include:

  • Rectal bleeding: This occurs when ulcers in the rectum open up, causing bleeding.
  • Anemia: Blood loss from rectal bleeding can lead to anemia. This is a condition in which the body lacks enough red blood cells to function normally.
  • Dehydration: The large intestines may become unable to absorb fluids properly, which can cause dehydration.
  • Malabsorption and nutrient deficiencies: The large intestines can also stop fully absorbing nutrients. Over time, this can lead to nutrient deficiencies.
  • Megacolon: This is where inflammation reaches deeper layers of the large intestines. Megacolon can be life threatening and require immediate treatment.
  • Cancer: People with ulcerative colitis may be 2 to 3 times more likely to develop colorectal cancer.

Learn more about UC and cancer.

Possible risk factors for proctosigmoiditis include:

  • having a family history of inflammatory bowel disease
  • smoking
  • being between 15–30 years old

Learn about the risks of leaving UC untreated.

If a person is experiencing diarrhea that lasts longer than a couple of days, they should contact a healthcare professional. This is particularly important if diarrhea occurs with bleeding, fever, or severe stomach pain.

A doctor will conduct a thorough medical evaluation and discuss a person’s medical history, family history, symptoms, and physical exam.

Further testing may include a colonoscopy. This involves feeding a long, flexible camera through the rectum into the large intestines. Doctors may also suggest other tests, such as blood or stool tests.

Learn more about a colonoscopy for UC.

The following are answers to questions people frequently ask about procotsigmoiditis.

What is the difference between proctosigmoiditis and ulcerative proctitis?

Ulcerative proctitis is inflammation of the rectum, while proctosigmoiditis inflammation extends to the sigmoid colon.

What is proctosigmoiditis in the stool?

Procotosignmoiditis can cause bloody diarrhea and left-side abdominal pain, as well as other symptoms.

IBD resources

Visit our dedicated hub for more research-backed information and in-depth resources on inflammatory bowel disease (IBD).

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Proctosigmoiditis is a type of UC that affects the rectum and large intestines.

It may be due to an overactive immune system, genetics, or environmental factors. People with a family history of the condition have a higher risk of developing it.

Complications can range from rectal bleeding to a higher risk of colorectal cancer. If an individual experiences any of the symptoms of the condition, they should speak with a healthcare professional.

While it is a lifelong condition, several types of medication are available for managing symptoms. Some people may require surgery.