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Diverticulitis: Classification & Types, Epidemiology, Pathophysiology, Causes, Risk Factors, Symptoms, Signs, Treatment, Investigations

Diverticulitis is a condition in which the diverticuli present in colon ruptures leading to infection of the surrounding tissues of colon. Increased pressure within a colon may cause pockets of tissue to push out from the walls of their colon with age. Such a small sac is known as diverticulum. These diverticula mostly occur near the end of the left colon called Sigmoid Colon, although they may occur in other areas of colon as well. The condition where these diverticula are present is called as diverticulosis.


Classification and Types of Diverticulitis

Diverticulitis is of different types with each one having its own symptoms and treatments.

  • Diverticulitis Uncomplicated in Stable Patients: Common symptoms are fever, abdominal pain, leukocytosis and inability to tolerate oral fluids due to vomiting.
  • Diverticulitis Uncomplicated in Older or Ill Patients: Common symptoms are fever, abdominal pain, leukocytosis, and inability to tolerate oral fluids due to vomiting. The patients are older than 85 years of age or are ill with some other medical condition.
  • Diverticulitis Complicated: Common symptoms are fever, abdominal pain, leukocytosis with or without sepsis, and presence of a perforation, fistula, abscess, or some obstruction.

Epidemiology of Diverticulitis

Diverticulitis is seen to be dependent on the number of diverticula present in an individual i.e., the more number of diverticula, the more chances of acquiring diverticulitis. 15 to 20% of the individuals with diverticulosis tend to develop diverticulitis. Diverticulitis is generally considered to be a disease of the elderly population, but as many as 20% of diverticulitis have been found to be younger than 50 years.

Diverticulitis is more common in Western countries presumably secondary to the lifestyle and dietary factors though the specific reasons are unclear.

It is believed that genetics play a role in addition to the dietary factors. Left-sided diverticula are predominant in the United States whereas right-sided diverticula are more prevalent in Asians including Asian Americans.

Both men and women are equally affected with diverticulitis.

Pathophysiology of Diverticulitis

The name diverticula is given to small herniations of mucosa that protrudes through intestinal layers as well as smooth muscles along natural opening which is formed by nutrient vessels present in wall of colon. Such herniations form small out-pouches lined by the mucosa. Diverticula usually occur in colon, although they have the potential to occur in any part of gastrointestinal tract. The intraluminal pressures are highest in sigmoid colon and hence it is generally the most affected part of colon.

When the diverticula get inflamed, this condition is known as diverticulitis. Undigested food particles or fecal material may accumulate in diverticulum resulting in obstruction. This then can lead to distension of diverticula due to excess growth of colonic bacterium and mucous secretion along with vascular compromise with subsequent macroperforation/microperforation can take place. It is also believed that increase in intraluminal pressures leads to erosion of diverticular wall leading to inflammation, perforation, and focal necrosis. More extensive disease and large perforations gives rise to formation of abscess along with rupture of intestine or in rare instances inflammation of peritoneum.

Another complication of this condition is formation of fistula. Fistulas to skin and adjacent organs may develop when there is abscess present. Colo-vesicular fistulas are quite common in men whereas in females uterus is interjected between bladder and colon. This complication in women is seen after a hysterectomy. However, colocutaneous and colovaginal fistulas can also form in rare cases.

Recurrent diverticulitis results in the scar tissue formation which results in narrowing and obstructing colonic lumen.

Causes and Risk Factors of Diverticulitis

The exact cause of diverticulitis is not known, but it generally results when feces or other food substances get trapped in diverticula that form along the wall of colon. This accumulated material causes the bacteria to grow and cause infection and inflammation resulting in increased pressure that may result in small perforation in the intestinal wall.

The most common risk factors include aging and poor fiber intake, which leads to constipation and hard stools.

Signs and Symptoms of Diverticulitis

Symptoms may last anywhere from hours to a few days.

The Most Common Symptoms are:

  • Pain, tenderness, and cramps in abdomen that is worse with movement.
  • Gas, abdominal swelling, and bloated feeling.
  • Constipation or diarrhea.
  • Vomiting associated with nausea.
  • Appetite loss.
  • Fever and chills.

In more severe cases where a fistula forms between colon and vagina or colon and urethra, air or stool passes out from vagina or urethra respectively.

Treatment of Diverticulitis

Treatment for diverticulitis is generally done in two phases.

Initial Treatment: Initial treatment for mild symptoms of diverticulitis includes:

  • Antibiotics and pain relievers.
  • Dietary changes such as clear-liquid or bland diet that is low in fiber until the pain goes away and then gradually increasing the amount of fiber intake.

When pain is severe with other complications, treatment includes:

  • IV antibiotics i.e., antibiotics given intravenously.
  • Intravenous fluids and nutrition for about a week to allow the bowels to relax.
  • Sucking out the contents through a nasogastric tube passed up the nose and down the throat into the stomach in case of vomiting and abdominal swelling.

Surgical treatment for complications such as fistula formation or removal of the part of colon in severe cases where the patient does not respond to conservative measures.

Elective surgery may also be done for diverticulitis in individuals younger than 40 years of age for cases of two or more severe attacks or who have a compromised immune system.

Ongoing Treatment: After recovery from an attack of diverticulitis, ongoing treatment is needed to prevent another attack. This includes:

  • Gradual increase in the amount of fiber intake in the diet in various forms.
  • Drinking plenty of fluids.
  • Regular follow up and sometimes colonoscopy or barium enema few weeks later to look for any other complications or problems such as inflammatory bowel disease or colon cancer.

Investigations for Diverticulitis

The first step towards investigation is a thorough physical examination and discussion about the symptoms. Other tests that may be recommended include:

  • Blood tests, such as a complete blood count (CBC).
  • X-ray.
  • CT scan.
  • Sigmoidoscopy.
  • Colonoscopy.
  • Ultrasound.


  1. Mayo Clinic. (2021). Diverticulitis. Source
  2. American Society of Colon and Rectal Surgeons. (2021). Diverticular Disease. Source
  3. National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). (2021). Diverticulitis. Source
  4. WebMD. (2021). Diverticulitis. Source
Team PainAssist
Team PainAssist
Written, Edited or Reviewed By: Team PainAssist, Pain Assist Inc. This article does not provide medical advice. See disclaimer
Last Modified On:August 10, 2023

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