Potential Diverticulitis Complications

Most cases of diverticulitis are not complicated and will get better with treatment and not occur again. However, some people will have more bowel problems (such as an abscess), another flare-up, or complications after treatment for diverticulitis. Of people who have symptoms of diverticulitis, about 15% will have complications.

This article will discuss the potential complications of diverticulitis and how commonly they may occur.

When Diverticulitis Is an Emergency

In some cases, diverticulitis can be a medical emergency. If you are experiencing symptoms of fever, severe abdominal pain, bleeding, or vomiting that won't stop, seek care immediately.

Healthcare provider checking screen in an operating room

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What Are Diverticulitis Complications?

Diverticular disease occurs when you develop outpouchings (diverticula) in your colon. In 20% of cases, diverticula become inflamed and infected, resulting in diverticulitis and causing symptoms such as abdominal pain.

Diverticulitis can cause various types of complications. This can include abscesses, bleeding, bowel obstructions, fistulas, bowel perforation, or needing bowel surgery, as follows:

  • Abscess: An abscess is a pocket of pus in the body caused by a bacterial infection. With diverticulitis, an abscess may appear in the abdomen. Symptoms may include abdominal pain. This complication might occur in up to 70% of people who have complicated diverticulitis.
  • Bleeding: Bleeding is not as common with diverticulitis as was once thought. It's now understood that bleeding is not a typical part of diverticular disease. Only about 5% of people with diverticulitis have this complication.
  • Bowel obstruction: An obstruction is when something is blocking the intestine and keeping the stool from moving through. In diverticulitis, the obstruction tends to be partial rather than total. The blockage is because the wall of the intestine becomes thicker and swollen. It then causes the interior of the intestine (the hollow space called the lumen) to become narrowed.
  • Fistula: A fistula is a connection between two organs or an organ and the skin that shouldn't be there. After having acute diverticulitis, about 14% of people might develop a fistula. Usually, the fistula runs between the colon and the urinary bladder, the small intestine, or the uterus.
  • Perforation: A perforation is a hole in the intestine. It may cause severe abdominal pain, nausea, and vomiting. Some perforations are small and can be treated with drainage and antibiotics. But larger ones might need surgery.
  • Surgery: Surgery is considered a complication of diverticulitis. Surgery might be done in response to a serious case of diverticulitis, or it might be elective surgery to improve quality of life. People with ongoing symptoms, such as pain, because of diverticular disease might decide that surgery to remove the diverticula is preferred.

Classification of Diverticulitis

Diverticulitis may be classified according to the complications. One such classification is called a Modified Hinchey classification. The features of the diverticulitis found on a computed tomography (CT) scan will help place it into a classification:

  • Stage 0: Mild clinical diverticulitis
  • Stage 1a: Inflammation confined to the colon
  • Stage 1b: An abscess confined to the colon (specifically in the last part of the large intestine, the sigmoid colon)
  • Stage 2: An abscess that's in the pelvis but outside the colon
  • Stage 3: Inflammation of the peritoneum (peritonitis) with pus
  • Stage 4: Peritonitis caused by an infection from fecal matter (stool)

Abdominal X-Ray vs. CT Scan

A plain X-ray of the abdomen is often used when trying to diagnose abdominal pain. However, it is not always the best test to diagnose diverticulitis. A CT scan is more accurate in diagnosing diverticulitis and can help avoid misdiagnosis.

One study showed that some cases of diverticulitis might be missed with an X-ray but are discovered with a CT scan.

Diverticulitis Complications After Surgery

Surgery may be used for diverticulitis to prevent symptoms that lower the quality of life and reduce the risk of complications. It might also be used to prevent a recurrence, especially if there have been two or more flare-ups of the condition. In one large study, about 20% of people had surgery when they had a second flare-up of diverticulitis.

Any surgery can lead to complications. Resection or colectomy surgery (removing all or part of the colon) to treat diverticulitis is no different. These range in seriousness and include anything from postsurgical pain to death.

Some of the potential complications after surgery for diverticulitis that have been studied include:

  • Abscess
  • Adhesions (scar tissue) in the abdomen
  • Bleeding
  • A leak of intestinal contents at the surgery site
  • Obstruction in the small bowel
  • Stricture (narrowing) at the surgery site 
  • Weakening of the abdominal wall (hernia

Between 6% and 15% of people have a recurrence of diverticulitis within five years after surgery.

An ostomy (routing a part of the intestine to the outside of the body) is a lifesaving procedure and can increase the quality of life. However, studies often frame an ostomy as a complication of diverticular disease.

In one study, elective surgery was sometimes used to avoid future complications that could lead to an ostomy. After one year, 1.6% of people treated medically and 4.0% of people treated with elective surgery had ostomy surgery.

Tips for a Successful Recovery

The reason behind diverticulitis surgery is to remove the problem, prevent complications, and avoid another flare-up. However, there is still a small chance of a recurrence of diverticulitis within the five years following surgery.

There is little in the way of proven guidelines to help recovery from this surgery and avoid further problems with diverticular disease. The surgeon and their staff will be the best source of information on routine post-op care and follow-up. However, some lifestyle changes may be recommended to help avoid a flare-up, as well.

Eating more dietary fiber is often recommended as a prevention method for diverticulitis. It’s not proven that a high-fiber diet will lower the risk of recurrence for everyone. However, it is considered a good suggestion because it is unlikely to cause harm and may have benefits.

Being more active and maintaining an appropriate weight may also be recommended to avoid further complications and a flare-up of diverticulitis. It’s important to check with a healthcare provider for advice before getting back to exercise after surgery or starting a new exercise program.

Smoking is associated with an increased risk of bleeding, sepsis (a whole-body reaction to a bloodstream infection), peritonitis, and colectomy surgery. Stopping smoking may be recommended to help avoid surgical complications.

Red Flag Symptoms After Surgery

A certain amount of post-op pain is expected. However, if the pain comes on suddenly or is severe, contact a healthcare provider as soon as possible. Other concerning symptoms include fever, bleeding, or heat or redness at the surgery site.

Co-Occurring Conditions in People With Diverticulitis

People who have diverticular disease may also have other health conditions. They may be related to diverticular disease or be found during treatment or follow-up. Co-occuring conditions include the following:

Colon Cancer

After diverticulitis has resolved, a colonoscopy might be scheduled. In a colonoscopy, a flexible tube with a camera is inserted through the anus to examine the inside of the colon.

During this procedure, a small percentage of people are discovered to have colon cancer. For uncomplicated diverticulitis, this is between 0.5% and 2% of people, and in complicated diverticulitis, this is between 8% and 11% of people.

Connective Tissue Disease

Diverticular disease appears to have a genetic component. Diverticulosis (having diverticula without symptoms) is associated with certain inherited connective tissue disorders.

People may be more likely to have diverticulitis if they also have a connective tissue disorder. This includes Marfan syndrome and Ehlers-Danlos syndrome.

Kidney Disease

Polycystic kidney disease may be associated with diverticular disease. Also, people who are experiencing chronic renal failure either before or after a kidney transplant may have a higher risk of diverticulitis.

Long-Term Diverticulitis Complications

Most cases of diverticulitis are treated conservatively and don’t cause any long-term problems.

A study following people for five years after a diverticulitis flare-up showed that about 90% don’t ever need surgery; 7% needed surgery during the first flare-up of diverticulitis; and 11% of the people treated without surgery who went on to have more flare-ups decided to have elective surgery for diverticulitis.

A large study found that 84% of people are treated for diverticulitis one time and it doesn’t occur again. People who had complicated diverticulitis with an obstruction, abscess, peritonitis, fistula, or sepsis had a higher risk of mortality.

The study authors suggest that surgery for diverticulitis be an individual decision that takes each person's condition into account. This is an update to the theory that having two flare-ups of diverticulitis is an automatic reason to have surgery.

People who have a first flare-up of complicated diverticulitis, which includes problems such as a large abscess that doesn’t get better with conservative treatments, may be considered candidates for surgery right away.

Living Well With Diverticulitis

If diverticulitis keeps coming back or there is ongoing pain, you may want to talk to a healthcare provider about surgery. Surgery used to be considered after two flare-ups of diverticulitis, but it’s being understood that it should also be considered when it can help improve quality of life and avoid complications and loss of quality of life.

There is not much information on how to avoid another flare-up of diverticulitis. However, there is some general advice that is usually given that is thought to potentially reduce the risks.

Some of these lifestyle changes include:

  • Eating more fiber and/or taking a fiber supplement
  • Getting enough exercise
  • Maintaining an appropriate weight
  • Stopping smoking

People who have had one flare-up of diverticulitis will want to be aware of changes in their bodies to catch another flare-up early.

Most people don’t experience another bout of diverticulitis. But if you do have recurring symptoms such as abdominal pain or tenderness or a change in bowel movements (having either more or less), talk to a healthcare provider as soon as possible to get evaluated.


Diverticulitis is often treated at home and does not recur. However, there are risks for complications in the bowel, such as an abscess, fistula, obstruction, or perforation. People with acute diverticulitis will want to seek treatment and follow up with a healthcare provider while recovering.

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Additional Reading

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.