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  • A condition in which a small sac forms along the colon and becomes blocked or inflamed
  • Symptoms include cramps, nausea, vomiting, fever, and constipation
  • Treatments include IV antibiotics or oral antibiotics and a clear liquid diet for several days
  • Involves Gastroenterology



No matter how hard we try, we cannot escape some of the natural side effects of aging. One of these is years of wear and tear on our intestines from eating, absorbing, and processing food. To push along digested food, muscles along the colon wall contract, applying pressure in a wavelike motion along the full length of the colon. This helps move waste to the rectum—our signal that we need to find a bathroom. 

Over time, repeated and sometimes uneven pressure—due to constipation, for instance—weakens the lining of the colon. Without its strong elasticity, the lining can bulge through the colon wall, forming a sac or pouch, a condition called diverticulosis. (The technical term for these small pouches is diverticula.) 

Most adults over age 60 have these pouches, which usually cause no problems. However, if a problem develops in one of these sacs, the result can be a painful and dangerous condition called diverticulitis.  

Diverticulitis can bring abdominal pain, fevers, and nausea, among other symptoms. Usually, diverticulitis can be resolved with mild treatments, including temporary diet changes and sometimes antibiotics. Most people with diverticulitis recover completely.

But, at its most severe, a pouch can burst open, spilling fecal matter directly into a person’s bloodstream. This results in an immediate risk of developing a blood infection called sepsis, which can be life-threatening. Occasionally surgery is necessary to repair a section of the colon with a burst pouch or to correct a fistula—an abnormal connection—that a pouch may have formed with a nearby organ. 

Yale Medicine’s expert team of digestive disease physicians and surgeons can help determine the best course of treatment for patients with diverticulitis. Our gastroenterologists rely on the latest evidence when deciding the best course of treatment for each patient. “We now understand that antibiotics may not be necessary to treat mild episodes of diverticulitis, and surgery may only be required for a minority of patients with complicated diverticulitis,” says Yale Medicine gastroenterologist Anil Nagar, MD

What causes diverticulitis?

Diverticulitis develops when a single sac (diverticulum) becomes blocked or filled by a piece of stool in the colon. Bacteria begins to grow inside the sac, leading to inflammation and infection. Researchers are unsure why this happens and how fiber in a diet contributes to or protects against the development of diverticulitis. 

What are the symptoms of diverticulitis?

Many people experience a sharp pain in the lower left side of their stomach, which is where sacs tend to develop (though they sometimes occur on the right, in which case the pain is felt there). Other symptoms may include the following: 

  • Cramps and extreme tenderness in your abdomen 
  • Fever 
  • Nausea and vomiting 
  • Constipation 

Who is at risk of developing diverticulitis?

Diverticulosis becomes more common after age 60. While researchers have not yet pinned down a way to identify who is at greatest risk for diverticulitis, the following factors appear to increase a person’s likelihood of developing it: 

  • Smoking 
  • Low activity lifestyle  
  • Certain medications, including steroids and opioids 
  • Obesity 
  • Certain genetically inherited diseases such as Marfan syndrome and Ehlers-Danlos disease, both of which affect connective tissue in the body and appear to increase an individual’s risk of developing the sacs at a younger age

New research suggests that cases of diverticulitis may be increasing in young adults. “This may be related to the increased prevalence of obesity, lack of physical exercise, and changes in our dietary patterns,” Dr. Nagar says.

How is diverticulitis diagnosed?

Because its most common symptom—severe abdominal pain—is tied to many conditions, diverticulitis is diagnosed through a process of eliminating other potential causes. Your doctor will likely start with a physical exam and medical history. The following tests may also be included as part of a diagnosis: 

  • Blood test
  • Stool sample 
  • Digital rectal exam 
  • CT scan, X-ray, and abdominal ultrasound imaging tests 

How is diverticulitis treated?

Treatment focuses on letting the colon rest and clearing up inflammation and infections. Recent research suggests that not all cases of diverticulitis require antibiotics, as previously thought. Some, but not all, patients require hospitalization. 

Inpatient (in-hospital) treatment. Patients with severe cases of diverticulitis may require intravenous antibiotics and fluids for several days. This approach allows the colon to rest. If a patient improves within a few days, he or she is usually sent home with a longer course of antibiotics. If the patient doesn’t improve, then surgery of the colon to remove sections with diverticula may be required. 

Outpatient treatment. Some patients can be safely treated without hospitalization, given a clear liquid diet and, if necessary, antibiotics. 

After recovery, a physician may recommend increasing the amount of dietary fiber in a person’s diet, but this varies on a case-by-case basis.  

“It is important to have a colonoscopy to check for colon cancer after an episode of diverticulitis,” Dr. Nagar says. “Fruits and nuts do not have to be avoided, and the routine use of probiotics does not appear to help prevent the disease.” 

What makes Yale Medicine unique in treating diverticulitis?

Most cases of diverticulitis are not severe and can be handled through routine care. However, for complicated or severe cases, a team of specialists, including gastroenterologists, interventional radiologists, and surgeons working together can provide the best personalized care for patients.