Definition & Overview

Diverticulosis refers to the formation of sacs called diverticula in the large intestines (colon). A diverticulum (singular) usually does not produce any symptoms, but it can get infected and develop complications, such as diverticular or rectal bleeding and diverticulitis. However, only about 20% of people with diverticulosis develop such complications.

The colon is made up of three layers; the inner layer called the mucosa, the middle layer called the muscularis, and the outer layer called the serosa. A colonic diverticulum is often referred to as a false diverticulum because it does not encompass all three layers, but only affects the outermost layer.

Diverticulosis is a common occurrence, especially in the western world. In the United States, it is estimated that 5% to 10% of adults will have the condition before age 50. 30% will have it after age 50. 50% will have it at age 70, and 66% will be affected with diverticulosis at age 85.

The majority of people with diverticula are not aware of their condition because of the absence of symptoms. In fact, most only find out about it during a medical examination for an unrelated condition.

Cause of Condition

Diverticulosis in itself should not be any cause for alarm. Only when the condition progresses into a diverticulitis or other complications, would the condition require treatment. The most common cause for the development of diverticula in the colon is straining due to constipation. Generating high pressure in the colon forces the mucosa to penetrate the muscularis and eventually cause a bulge in the serosa (outer layer of the colon).

The exact reason this happens remains a mystery, but researchers believe that lack of dietary fiber may contribute to its occurrence. Fiber helps prevent constipation, which often results in unnecessary pressure on the colon. Therefore, fiber plays a big role in preventing the formation of diverticulum.

However, once diverticula have formed, it would be difficult to prevent an inflammation that could lead to infections and diseases. Inflammation can occur suddenly and without any warning. It is only during this time that symptoms would appear.

Key Symptoms

It’s important to understand that uncomplicated diverticulosis normally does not display any symptoms. In rare cases, patients would experience abdominal pain, altered bowel habits, or flatulence. However, the symptoms would only be temporary and could be caused by other conditions, such as irritable bowel syndrome (IBS).

Once diverticulosis has progressed into acute diverticulitis, patients will notice symptoms, such as pain in the lower left quadrant, nausea and vomiting, constipation, diarrhea, urinary difficulties, chills and fever, and a condition called leukocytosis.

Diverticulitis is considered a serious disease, mostly because when the sac bursts, it will spread bacteria and feces into the abdominal cavity. In some cases, the infection is confined to the colon wall and can be treated using antibiotics, fluids, and bed rest. However, if the infection spreads and abscess forms, it would require a surgical procedure to remove the abscess and correct the condition.

Who to See & Types of Treatment Available

The symptoms of diverticulitis are similar with other medical disorders, so it would be likely that the first person to see is your doctor who should already be familiar with your medical history and this would be an advantage.

After reviewing your medical history, the doctor will perform a physical examination, which could include a digital rectal exam. If the doctor begins to suspect diverticulitis, other tests, such as an x-ray, CT-scan, ultrasound, colonoscopy, and blood tests will be ordered to determine the presence of infections.

If rectal bleeding is severe, the doctor may opt to perform an angiography to locate the source and stop the bleeding. However, not all cases of diverticulitis are severe. In fact, less serious cases may not require hospital admission. The condition would only be treated using antibiotics and pain medications if necessary. Bed rest, drinking plenty of fluids, and increasing consumption of fiber-rich foods should be enough to treat the condition.

If the doctor determines the presence of an infection and abscess, a surgical procedure will be performed. The degree of severity of the condition will determine what would need to be done during surgery. If the abscess remains intact, the surgeon will drain the fluid using a needle.

In severe cases, such as abscess draining into the abdominal cavity (peritonitis), the intestines will be cleaned, and if a blockage is present, it will be removed. Peritonitis is a serious condition because abscess in the abdominal cavity will result in the spread of infection. When this happens, the condition can be fatal.

It is also likely that the affected part of the colon will be removed. This is because infections can cause scarring, which can lead to the formation of a blockage.

Diverticulitis can also result in the formation of a fistula, which is an abnormal connection between organs. Surgery will also be required to remove the fistula.

The majority of diverticulosis cases remain undetected until they are stumbled upon during an unrelated medical exam. However, this doesn’t mean that the condition can’t be prevented. The first step in prevention is to maintain good bowel habits, which means avoiding straining and constipation. To do so, you’ll need to increase your fiber intake, drink plenty of fluids, and exercise regularly.


  • Fox JM, Stollman NH. Diverticular disease of the colon. In: Feldman M, Friedman LS, Sleisenger MH, eds. Sleisenger & Fordtran's Gastrointestinal and Liver Disease. 8th ed. Philadelphia, PA: Elsevier Saunders; 2010:chap 117.

  • Prather C. Inflammatory and anatomic diseases of the intestine, peritoneum, mesentery, and omentum. In: Goldman L, Schafer AI, eds. Goldman's Cecil Medicine. 24th ed. Philadelphia, PA: Elsevier Saunders; 2011:chap 144.

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