Colon Diverticulitis

Article Author:
Stephanie Carr
Article Editor:
Alfonso Velasco
6/22/2019 8:25:34 AM
PubMed Link:
Colon Diverticulitis


Diverticulitis has increased in incidence over the past few decades, becoming a major healthcare burden for Western countries.[1] In the United States, acute diverticulitis results in nearly 200000 hospital admissions and $2.2 billion of health care costs per year.[2] Although the prevalence of the disease increases with age, younger adults may also develop diverticular disease. In fact, for some time, it was thought that younger patients and male patients were more likely to experience a more aggressive form of diverticulitis with an increased complication rate and higher recurrence.[3] However, recent studies have challenged this concept. Environmental and genetic risk factors result in the development of diverticular disease, although good quality evidence for many of these factors remains insufficient. Most cases of diverticulitis undergo successful management in the outpatient setting with oral antibiotics and temporary dietary restrictions. The decision to perform elective sigmoid colectomy in patients that recover from uncomplicated diverticulitis is controversial and requires case-by-case consideration. Surgical treatment is the recommendation in cases of complicated diverticulitis.


Diverticular disease starts with an out-pouching of the mucosa of the colonic wall. Inflammation at each mucosal out-pouching contributes to diverticulitis. The presumed mechanism of diverticulitis is an overgrowth of bacteria due to obstruction of the diverticular base by feces with micro-perforations. This theory has been challenged in recent years as some studies demonstrate that in selected cases resolution of uncomplicated diverticulitis may occur without antibiotics.[4]


Diverticulosis of the colon is common in Western countries and increases with age. Over 50% of individuals over the age of sixty have diverticulosis, and the incidence rises to 70% after eighty years of age.[5] Despite the significant prevalence of diverticulosis in the population, only 4% of individuals will develop diverticulitis in their lifetime.[6] The distribution of the colonic diverticula varies depending on population demographics. In Western countries, diverticula are most common in the sigmoid colon with a rate of 65%.[1] The right colon is more commonly involved in Asian populations. This difference was once attributed to daily dietary fiber, but epidemiologic studies have refuted this concept. These studies have analyzed Asian populations after relocation and change in dietary habits, but there is not yet proof of any change in diverticular pattern.[7] Although environmental factors play a significant role in the development of diverticulosis, studies on identical twins have identified a strong genetic predisposition.[8]

Multiple environmental risk factors have been postulated in the development of diverticular disease; however, many remain controversial. A 1970 study hypothesized that a diet high in fiber was protective against diverticular disease, but evidence in this regard is conflicting.[9] For patients with a history of diverticulitis, The American Gastroenterology Association (AGA) and American Society of Colon and Rectal Surgeons (ASCRS) recommend a diet high in fiber. In this setting, increasing dietary fiber correlates with a reduction in the development of recurrent episodes of acute uncomplicated and complicated diverticulitis[10]

In the past, patients with diverticular disease were discouraged from eating nuts, seeds, and popcorn, but a recent study determined that these foods do not increase the risk of developing diverticulitis.[11] Red meat, particularly beef and lamb, have been associated with an increased risk of hospitalization for diverticulitis. Obesity, smoking, and alcohol use are also associated with a higher incidence of diverticular disease.[12] Medications including NSAIDs, ASA, and acetaminophen seem to increase the risk of developing complicated diverticulitis. Current corticosteroid use doubles the risk of developing perforated diverticulitis.[13]

There are also postulates regarding protective factors. Vigorous exercise, such as running, has shown a risk reduction for the development of complicated diverticulitis by 25%. Light activity, such as walking, is less effective.[14] Statin medications appear to reduce the risk of perforated diverticulitis.[13] Maintaining a normal weight and eliminating smoking also decreases the risk of diverticular disease.


Despite the high prevalence of diverticulosis, the pathophysiology of the disease is not well understood. A colonic diverticulum is an out-pouching of the colonic mucosa through the weakest point in the colonic lumen where the vasa recta penetrate the colonic wall to supply blood to the submucosa and mucosa. Patients with diverticulosis have increased intraluminal pressures during peristalsis.[4] High colonic intraluminal pressure associated with constipation and straining during defecation was once thought to be the initiating factor resulting in mucosal herniation through the colonic wall, but this theory is currently under question.[8]

History and Physical

Most patients with diverticulosis are asymptomatic, and the presence of diverticula is commonly identified incidentally during colonoscopy or radiologic studies. Patients with acute diverticulitis may present with fever, left lower quadrant pain, and change in bowel habits. Laboratory findings include leukocytosis and possibly elevated inflammatory markers.[15] Those patients with complicated diverticulitis may present with signs of sepsis and physical findings consistent with peritonitis. The presence of fecaluria and pneumaturia must alert the clinician to the possibility of a colovesical fistula. 


When the history, physical exam and laboratory finding are consistent with the diagnosis of acute diverticulitis, confirmatory imaging studies are the next step. Different imaging modalities including ultrasound and barium enema may be used to diagnose diverticular disease. However, CT scan of the abdomen and pelvis with intravenous and oral contrast is the preferred modality. Its diagnostic accuracy is high with a sensitivity of 98%.[16]  Findings of colonic wall thickening and fat stranding are typical for diverticulitis.  Signs of complicated disease including fistula formation, abscesses, and intra-abdominal free air are easily identifiable with scan.[17] The Hinchey classification system is useful in determining the severity of disease as well as in the allocation of patients to different treatment algorithms.

Generally speaking, patients with Hinchey 1a and 1b diverticulitis are successfully manageable by non-surgical means. Patients with Hinchey 2 diverticulitis may require placement of a percutaneous drain followed by elective sigmoid colectomy. Patients with Hinchey 3 and 4 require urgent surgical intervention.

Treatment / Management

The medical management of acute non-complicated diverticulitis includes oral or intravenous antibiotics, pain control, hydration, and restricted oral intake. Medical management of diverticulitis with antibiotics remains the standard of care. However, antibiotic choice, duration of treatment, and route of administration remain controversial.[18] Most cases of uncomplicated diverticulitis are successfully treatable in the outpatient setting. Oral antibiotics, such as ciprofloxacin and metronidazole or amoxicillin-clavulanate are prescribed for 7 to 10 days with recommendations to minimize oral intake until the pain has resolved.[15]

Patients who are febrile, immunosuppressed, unable to stay hydrated or those with multiple medical co-morbidities require admission to the hospital for treatment with parenteral antibiotics. As symptoms improve, the diet is advanced, and patients transition to oral antibiotics. Any patient failing to improve on parenteral antibiotics or deteriorates during therapy should undergo repeat evaluation with CT imaging to rule out evolving complications.[15]

After acute episode resolution of diverticulitis, a colonoscopy is recommended 6 to 8 weeks later, particularly if the patient has not had a colonoscopy in the past 2 to 3 years.[15]

Historically, elective sigmoid colectomy was performed after the second bout of uncomplicated diverticulitis. However, more recent evidence has disproved the benefit of this approach.  First, the recurrence rate of uncomplicated diverticulitis is lower than previously estimated, ranging from 13 to 23%. Second, the incidence of recurrent complicated episodes that may require a stoma is also low, approximately 6%. Therefore, current recommendations emphasize that selection criteria for elective surgery should be individualized according to the number, severity, and frequency of episodes of diverticulitis, persistent symptomatology after an episode of diverticulitis and the immunologic status of the patient. These criteria merit consideration in the context of the patient’s age, comorbidities, and social history. Finally, routine sigmoid colectomy in patients younger than 50 years of age is no longer the recommended therapeutic path.[10] Younger patients should receive the same treatment as their older counterparts.

Regardless of the indication and or technique used (open, laparoscopic or robotic) when performing an elective sigmoid colectomy for diverticulitis, it requires the removal of the entire sigmoid colon, the proximal and distal anastomotic sites must appear healthy and well perfused, and the anastomosis performed without tension.

Approximately 1% of patients with an acute episode of diverticulitis will require surgical intervention during that episode.[19] Patients presenting with signs of peritonitis are candidates for emergent surgery.  When intraoperative findings confirm perforated diverticulitis, the traditional operation is a Hartmann’s procedure, which includes resection of the sigmoid colon, preservation of the rectum in the form of a rectal pouch and creation of an end colostomy. This procedure effectively eliminates the risk of an anastomotic leak and patients are considered for colostomy reversal in 3 to 6 months. However, due to old age and associated comorbidities nearly 30% of patients undergoing a Hartmann’s procedure never have colostomy reversal.[15] A second option for patients with Hinchey 3 and 4 disease is a primary colorectal anastomosis with a proximal diverting ileostomy. Initial retrospective evaluation of this surgical modality shows a decreased overall mortality after performing a primary anastomosis. However, randomized controlled studies comparing a Hartmann’s procedure to primary anastomosis with proximal diversion are not yet available.[20] An old approach, no longer considered in the surgical management of complicated diverticulitis, consisted of leaving the inflamed or perforated sigmoid colon in situ and placement of a proximal stoma with the plan of second and then third stage procedures.

Pertinent Studies and Ongoing Trials

Recent studies have demonstrated the resolution of uncomplicated diverticulitis without the use of antibiotics in very well selected patients. Exclusion criteria in these trials were patients with peritonitis, perforation, signs of sepsis and hemodynamic instability. Although some patients did develop perforations or abscesses, the risk was considered low, and there was no difference in primary outcomes between the group treated with antibiotics and the group without antibiotic therapy.[18] The evidence for this unique treatment approach is preliminary, and further study is needed.

Traditionally, patients with generalized peritonitis from perforated diverticulitis undergo a Hartman’s procedure or primary anastomosis with a proximal diverting stoma. Researchers have studied laparoscopic peritoneal lavage as an alternative to the standard surgical treatment of perforated diverticulitis.[21] Other studies have not duplicated the initial results, so this treatment remains controversial.

Enhancing Healthcare Team Outcomes

The incidence of diverticulitis continues to increase in all age groups, placing a substantial burden on the healthcare system. The primary care physician, nurse practitioner, gastroenterologist, and the dietitian must educate the public and patients that obesity, inactivity and a poor diet are important contributing epidemiologic factors.

A positive paradigm change in the treatment of diverticulitis has resulted in the widespread use of outpatient management for non-complicated diverticulitis. However, many patients with a history of non-complicated diverticulitis are improperly managed empirically with antibiotics every time they call their doctor’s office with abdominal pain. This misuse of antibiotics must be corrected.  For patients undergoing surgery, a colostomy nurse should educate the patient on the care of the stoma.

Better and more sophisticated imaging modalities have allowed us to accurately classify the severity of disease and allocate different patients to more effective treatment algorithms.

The current emphasis on individualizing the need for elective sigmoid colectomy after resolving non-complicated diverticulitis will result in less unnecessary operations and better outcomes.

Finally, the present management of diverticulitis must be delivered by interdisciplinary teams in the context of the most recent scientific evidence. These teams can include physicians, specialists, gastroenterology specialty-trained nurses, and pharmacists, working collaboratively to bring about optimal patient care and outcomes. [Level V]

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      Contributed by Stephanie Carr DO


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