Diverticulosis, Diverticulitis – What’s the difference – How to prevent – When to scope

A diverticulum is a sac like protrusion through a weak area in the muscle wall of the colon. The condition of having diverticula [i] is called diverticulosis. The diverticulosis may not cause any problems, if it does, we say that a patient has symptomatic diverticular disease. More about that in a minute. Diverticulosis is most frequently seen in the colon segment known as sigmoid colon, the part of the large intestine that is closest to the rectum. Diverticulosis is very common, and 60 % of 60-year old people will have diverticulosis.

Why do we get diverticula?

Diverticula develop at areas of weakness in the muscle component of the colon wall. The weakness arises because blood vessels that run around the colon circumference give off vessels which pierce straight through the colon wall to supply the inner lining (mucosa) of the colon (see image). Eventually the mucosa prolapses alongside these blood vessels and can be seen on the outside of the colon.

Nobody is sure why some people have more diverticula than others and why some people have no diverticulosis at all. Risk factor include fat and red meat, obesity, and lack of physical activity. The role of fiber is unclear with studies giving conflicting results.

Diverticula are outpouchings alongside of blood vessels that go through the muscle wall of the colon.

Should I avoid seeds, nuts and popcorn to prevent problems with diverticulosis?

No. Nut, corn, and popcorn consumption are not associated with an increase in risk of diverticulosis, diverticulitis or diverticular bleeding. In a large observational study (The Health Professionals Follow-up Study) that included 47,228 men between the ages of 40 and 75 years.

What are the diseases caused by diverticulosis?

Most people with diverticulosis never develop problems. Those who do may develop diverticulitis, diverticular bleeding, symptomatic uncomplicated diverticular disease (SUDD), or segmental colitis associated with diverticulosis (SCAD)


Diverticulitis happens when pressure on the diverticula or dried out stool material wears the mucosal wall thin which leads to inflammation, infection, and sometimes perforation. Patients typically have pain the left lower quadrant of the abdomen, constipation (50 %) or diarrhea (25 – 30 %). The average age upon presentation is 63 years, but diverticulitis is not infrequent in those who under 45. Fever may be present. Many patients have had attacks before. The abdomen may be tender when the doctor examines you, and blood tests may be abnormal. However, a CT scan of the abdomen is a crucial test in the diagnosis of diverticulitis. Treatment is typically by a two-antibiotic regimen for 7 – 10 days.

Diverticulosis means the mere presence of diverticula. Diverticulitis means when there is inflammation with abdominal pain. The orange red indicates pus.

Why colonoscopy after diverticulitis?

Colonoscopy should not be done when you are having an attack of diverticulitis. Experts recommend, however, that a colonoscopy should generally be performed at least six weeks after recovery to definitively rule out the presence of an underlying colorectal cancer, unless you have had a colonoscopy within the previous year.

Diverticular bleeding

We have already said that blood vessels that run around the colon circumference give off vessels which pierce straight through the colon wall to supply the inner lining (mucosa) of the colon. These are areas of weakness through which the mucosa (inner lining of the colon) prolapses, forming a diverticulum. The outpouching also affects the blood vessel, which gets stretched and exposed to injury up to the point where it bursts. This results in painless bleeding which can be severe, but, fortunately, resolves by itself most of the time. If it does not colonoscopy and or angiography (x-rays of blood vessels) may be required.

Symptomatic uncomplicated diverticular disease (SUDD)

Having diverticulosis normally causes no symptoms unless there is diverticulitis, at least that was a long-held belief. More recently, Symptomatic Uncomplicated Diverticular Disease (SUDD) has received increasing attention, as a disease it remains virtually unknow outside of GI specialist circles. It basically looks like Irritable Bowel Syndrome (IBS) but is caused by the presence of diverticula and is treated differently.  I will devote a special post to this topic.

Segmental colitis associated with diverticulosis (SCAD)

Segmental colitis associated with diverticulosis is important mostly because the unwary can confuse it with other problems. It can, for example, be a cause of rectal bleeding, chronic diarrhea and cramping abdominal pain.

How to prevent symptoms from diverticulosis

An increase fiber intake will probably not prevent you from forming diverticula in your colon, however, more fiber in your diet means a lower risk of getting problems with your diverticulosis. This was borne out in two large studies involving 47,888 US men published in 1994 and 47,033 men and women from the UK published in 2011.  Please remember, you can have nuts, seeds, corn and berries!

Our thinking about diverticular disease is changing. Especially symptomatic uncomplicated diverticular disease (SUDD) is often confused with “IBS” (Irritable Bowel Syndrome). Please make an appointment with Dr. Klaus Gottlieb in Templeton, CA, or San Luis Obispo, CA, if you have bowel symptoms that keep bothering you.

[i] The plural of the neuter Latin word diverticulum is diverticula, not diverticuli (like: medium – media).

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