Firstly, let’s define these different terms. Diverticulosis refers to the presence of pockets in the wall of the colon. You Latin scholars will know that a ‘diverticulum’ refers to one; ‘diverticula’ refers to more than one. A diverticulum can be small in size (size of a grape seed) or large (size of a grape). Diverticulitis refers to a specific situation where the diverticula become infected. Diverticular disease is an all-encompassing term that refers to all of the above. The terms diverticulosis and diverticulitis are often confused; typically one will use the word diverticulitis when they actually mean diverticulosis. Enough of the nomenclature.
Diverticulosis is rare in developing countries but is common in Western societies. As more countries adopt ‘Western’ diets, the prevalence of diverticulosis has increased. Diverticulosis is about 3 times more common now than in the early 1900s likely due to our worsening eating habits. Diverticulosis affects men and women equally and increases with age. Approximately 10-20% of adults younger than 40 are affected and this rises to 50-70% among people 80 or older. Diverticula most commonly occur in the sigmoid or descending colon (lower half of colon) but can develop in any part of the colon.
It is fairly well accepted that diverticula develop in the setting of a diet that is low in dietary fiber and high in refined carbohydrates such as sugar and processed bread. Diverticulosis is less common among vegetarians. Low intake of dietary fiber results in less bulky stools that retain less water and are more difficult to pass. This leads to an increase in the pressure within the colon that leads to the formation of diverticula which are outpouchings in the wall of the colon. The analogy I like to use with patients is if one takes a small inflated balloon into one’s palm and squeezes the balloon with open fingers, bulges in the balloon will form between your fingers which are similar to how diverticula are formed. Straining at stool to evacuate hard stools is equivalent to squeezing the balloon. Other factors that are associated with diverticulosis include physical inactivity, constipation, obesity, and smoking tobacco.
Most people with diverticulosis do not know they have the condition. Diverticulosis is most commonly diagnosed at the time of a colonoscopy. When symptoms occur, they are generally due to one of three situations which I will address further below: (1) spasm of the colon wall muscles; (2) bleeding from the diverticula; or (3) infection of the diverticula known as diverticulitis.
Pain due to colon wall muscle spasm
Patients with diverticulosis may experience discomfort in the left lower abdomen. This is due to spasm of the intestinal wall muscles and is not related to inflammation or infection. Associated symptoms can include bloating, constipation, or diarrhea. Treatment includes a high fiber diet or fiber supplementation. Intake of 20-35 grams of fiber per day is recommended. For help in calculating your daily intake of fiber, download a free copy of my fiber guide. The role of probiotics in this situation is unclear.
Bleeding from diverticulosis is the most common cause of lower GI bleeding and typically occurs in the absence of infection (diverticulitis). Approximately 5-15% of patients with diverticulosis will experience diverticular bleeding. Diverticular bleeding stops spontaneously in 70-80% of cases. Blood loss is usually abrupt, painless, and large in volume. This is in contrast to bleeding from hemorrhoids which is typically smaller in volume and often related to discomfort or itching around the anus. Patients with diverticular bleeding usually need to be hospitalized and treated with intravenous fluids and supportive care. As mentioned above, bleeding stops spontaneously in up to 80% of cases. If bleeding persists, treatments may include controlling bleeding through colonoscopy therapies, interventional radiology therapies, or surgery.
Although most people with diverticulosis never have symptoms, less than 5% will develop diverticulitis over the course of their lifetime with the greatest likelihood affecting those patients diagnosed with diverticulosis in their 40s. The underlying cause of diverticulitis is a small or micro perforation of a diverticulum. It was previously believed that obstruction of diverticula by stool increased diverticular pressure and caused perforation; such obstruction is now thought to be rare. The primary process is likely erosion of the diverticular wall by increased pressure within the colon or due to food particles within the diverticulum. The inflammation is frequently mild, and a small perforation is walled off by the fat layer surrounding the colon. This may lead to a localized abscess or, if adjacent organs are involved, a fistula (connection between two structures) or obstruction.
Symptoms of diverticulitis include abdominal pain, fevers, chills, change in bowel habits, nausea, vomiting, and decreased appetite. Rectal bleeding is rare. A CT scan is the diagnostic test of choice. Complications including abscess formation, obstruction, and perforation arise in 25% of patients.
Uncomplicated diverticulitis is treated with antibiotics. Mild cases can be treated in the outpatient setting. Hospitalization may be needed for IV antibiotics and IV fluids. An abscess may require surgical drainage. Surgery may be required for complications such as a perforation or fistula formation.
After recovery from the first episode of acute diverticulitis, one-third of patients will develop a second episode. After a second attack, another one-third of patients will have a third attack. Patients with right-sided diverticulitis are at low risk of recurrence, while patients with a long segment of involved colon, diverticular abscess, or a family history of diverticulitis are at a high risk of recurrence. Surgery for recurrent mild and uncomplicated diverticulitis should be individualized for the patient.
For those of you who enjoy seeds, nuts, and popcorn, you will be glad to know that there is no evidence to link them to an increased risk of developing diverticulitis. Lastly, it is important to know that having diverticulosis does not increase one’s risk of developing colon polyps or colon cancer.
Here’s to your colon health!
Frank Farrell, MD, MPH, AGAF