What is Diverticulitis?
Diverticulitis—a disease of the colon that causes lower abdominal pain—is becoming increasingly common in the United States in the over-50 population. As we age, become more sedentary, and eat Western-style diets devoid of fiber, many of us start to develop small, weak areas in the muscular wall of the colon. This allows the colon’s lining to protrude through, forming tiny pouches called diverticuli. (See also our post “Diverticulitis Diet: Make Smart Food Choices to Keep the Pain at Bay.”)
Diverticulitis Risk Factors and Symptoms
It’s fortunate that diverticuli usually don’t cause any symptoms, given how common they are: 50 percent of people at age 50 years, 60 percent at age 60 years, and almost 70 percent of people in their 70s and 80s are estimated to have diverticulosis, which is how the condition is defined when the presence of diverticula causes no symptoms. In up to 20 percent of people with diverticulosis, however, the diverticuli bleed or become inflamed or infected, leading to what is called diverticulitis.
Abdominal pain, fever, and constipation are common diverticulitis symptoms, but, as you will soon see, medical researchers have recently discovered that the symptoms of diverticulitis are much more variable than traditionally thought.
Acute Diverticulitis Symptoms
So what does a diverticulitis attack feel like? Diverticulitis symptoms often include the following:
- Lower abdominal pain (occurs on left side in 70 percent of patients; often described as crampy)
- Change in bowel habits
- Nausea and vomiting
Diverticulitis symptoms depend on many factors, including the location of the inflamed diverticula in the abdomen, the severity of the inflammatory process, and the presence of complications (see below).
Some people have a single, acute episode experiencing symptoms of diverticulitis, never to have the problem again. Other people may suffer from recurrent, distinct episodes. In these cases, the diverticulitis pain is often severe and comes on suddenly, but it can also be mild and become worse over several days. The intensity of the diverticulitis pain can fluctuate.
Occasionally, diverticulitis leads to bleeding; infections; small tears, called perforations; or blockages in the colon. Bleeding diverticula can lead to blood in the stool. Infected diverticula can form abscesses or can perforate and leak infected fluid into the abdominal cavity, which can lead to body-wide infection (sepsis), fever, chills, and severe abdominal pain.
Fistulas may form if infection spreads outside the colon and causes the colon’s tissue to stick to nearby tissues, such as the bladder. This may cause chronic, severe bladder infections with associated pelvic pain. Scarring caused by infection may lead to partial or total blockage of the intestine, called intestinal obstruction. When the intestine is blocked, severe constipation, bloating, and pain occurs.
Chronic Diverticulitis Symptoms
Not all people with diverticulitis have distinct, acute episodes separated by symptom-free periods. In fact, what is becoming more and more obvious to medical experts in recent years is that a number of people have a chronic, low-grade form of diverticular disease that causes ongoing symptoms which mimic the symptoms of irritable bowel syndrome (IBS).[3-4]
Factors leading to symptoms in this chronic form of diverticular disease include:
- Low-grade inflammation,
- Altered intestinal gut bacteria (microbiota),
- Hypersensitivity of the gut tissue to pain,
- Abnormal gut motility.
For these people, symptoms often include more vague abdominal pain and discomfort, bloating, constipation, and diarrhea. The onset of the IBS-like abdominal pain is often associated with a change in frequency and/or form (appearance) of stool and is typically relieved with defecation.
For complicated cases of diverticulitis, hospitalization and surgery are often required.
New treatment options, however, are available that don’t involve strong antibiotics or invasive surgery. While antibiotics and surgery have traditionally been the conventional treatments of choice, new evidence shows that they are typically not helpful or necessary.
Originally published in 2016, this post is regularly updated.
 Dig Dis Sci. 2015 Oct 12. [Epub ahead of print]