Diverticulitis is a painful condition that occurs when small, pouch-like structures along the digestive tract, called diverticula, become inflamed or infected. Most cases of diverticulitis, about 75 percent, are uncomplicated and can be resolved without hospitalization.

However, some 25 percent of diverticulitis cases lead to complications that require hospitalization or surgery because these problems can be life-threatening. You should speak with your doctor immediately if you have diverticulitis and experience any of the following symptoms:

  • Fever over 100 degrees Fahrenheit
  • Worsening or severe abdominal pain
  • Inability to tolerate fluids
  • Low blood pressure

Some of the complications that can result from diverticulitis include:

  • Abscess: a swollen, pus-filled area located just outside the colon wall, caused by infection
  • Peritonitis: an infection of the peritoneum, the inner lining of your abdominal wall
  • Fistula: an abnormal passageway that forms between two organs (e.g., the intestine and the bladder) or between an organ and the abdominal wall
  • Intestinal obstruction: partial or total blockage of food or stool through the intestines
  • Rectal, or diverticular, bleeding and hemorrhage
  • Increased risk of irritable bowel syndrome (IBS)

Diverticulitis and Abscesses

An abscess is a walled-off collection of white blood cells and bacteria — commonly known as pus — that forms inside your body. Abscesses are typically accompanied by swelling and inflammation, and can cause abdominal tenderness and severe abdominal pain.

In the case of diverticulitis, abscesses form when the infection from a diverticulum spreads from your large intestine to other areas of your body. Most commonly, diverticular abscesses appear in the pelvic area or in the mesentery, the tissue that connects your intestines to the back wall of your abdomen.

Only about 15 percent of people with diverticulitis develop abscesses, and for those who do, there are a number of treatments for this condition that do not involve surgery. Some small abscesses (less than two centimeters in diameter) may resolve on their own with the help of antibiotics. However, larger abscesses may need to be drained using a thin plastic catheter inserted through the skin, a process known as percutaneous catheter drainage.

If, for some reason, your doctor cannot treat a diverticular abscess using a catheter, he or she may recommend surgery to create an opening in the skin, called a stoma, from which the abscess can be drained.

Diverticulitis and Peritonitis

Peritonitis is an infection of the peritoneum, the silk-like membrane that lines the inside of your abdomen.  Diverticular peritonitis occurs when the infection from a diverticulum spreads outward from a perforation or hole in the wall of the colon into the abdominal cavity.

Symptoms of peritonitis include severe abdominal pain, fever and chills, nausea, vomiting, and bloating of the abdomen.

Unlike in an abscess, the bacteria that cause peritonitis are not confined to one small area, but can spread throughout the entire body.

For this reason, peritonitis is considered a life-threatening complication of diverticulitis and should be treated immediately.  Patients who experience peritonitis as a result of diverticulitis usually undergo emergency surgery, which removes the infected part of the colon. A second surgery is then necessary to rejoin healthy sections of the colon.

Diverticulitis and Fistula



Fistulas are more common in men than in women. However, women who have had a hysterectomy are at a higher risk of developing this complication because the uterus, which normally separates the large intestine from the bladder, has been removed.

Diverticular fistulas commonly form between the colon and the bladder and can lead to a bladder infection or a urinary tract infection (UTI). Fistulas may also form between the colon and other organs or body parts, such as the small intestine, uterus, vagina, abdominal wall, or thigh.

Bowel Obstruction and Diverticulitis

Bowel obstruction, intestinal blockage, and stricture formation all describe complications that can arise from diverticulitis. In some cases, inflammation from diverticulitis can narrow the intestinal cavity, making it difficult for waste to pass through the body. This narrowing of the bowel is known as a stricture.



Complete blockage of the bowels requires emergency surgery to correct. People with this condition will often feel extreme abdominal pain and nausea and won’t be able to pass gas or have bowel movements.

Diverticular Bleeding

Diverticular bleeding occurs when small arteries inside a diverticulum erode, causing blood to leak into the colon. People who experience diverticular bleeding may notice maroon or bright red blood in their stool. This is usually painless bleeding.

In most cases, this problem will resolve on its own. However, rectal bleeding can also be a symptom of other health issues, such as colon cancer. Therefore, if you experience this complication, you should see your health care provider to determine its cause.


Diverticular hemorrhage is a serious complication and typically requires hospitalization. In some cases, people may require a blood transfusion, as well as surgery to remove the segment of the colon containing the bleeding diverticulum.

Irritable Bowel Syndrome (IBS) and Diverticulitis

Anecdotal evidence has long supported the belief that diverticulitis can cause irritable bowel syndrome (IBS), a gastrointestinal disorder that leads to abdominal pain and discomfort. But until recently, little data existed to support this belief.

However, a 2013 study published in the journal Clinical Gastroenterology and Hepatology suggests that patients with diverticulitis may be at a higher risk of developing IBS and other functional bowel disorders. The researchers call this complication "postdiverticulitis IBS."