Updated: Aug 15, 2017
  • Author: Kamyar Shahedi, MD; Chief Editor: BS Anand, MD  more...
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Practice Essentials

Diverticular disease includes a spectrum of conditions ranging from asymptomatic diverticular disease, to symptomatic uncomplicated diverticular disease, and complicated diverticular disease that includes acute and chronic diverticulitis. Diverticulitis is defined as an inflammation of one or more diverticula, which are small pouches created by the herniation of the mucosa into the wall of the colon. Diverticulitis is generally considered a disease of the elderly, but as many as 20% of patients with diverticulitis are younger than 50 years. In its chronic form, patients may have recurrent bouts of low-grade or overt diverticulitis.

See Can't-Miss Gastrointestinal Diagnoses, a Critical Images slideshow, to help diagnose the potentially life-threatening conditions that present with gastrointestinal symptoms.

Signs and symptoms

The clinical presentation of diverticulitis depends on the location of the affected diverticulum, the severity of the inflammatory process, and the presence of complications. Presenting complaints include the following:

  • Left lower quadrant pain (70% of patients)

  • Change in bowel habits

  • Nausea and vomiting

  • Constipation

  • Diarrhea

  • Flatulence

  • Bloating

Physical findings in patients with diverticulitis mirror the severity of the inflammation and the presence of complications, as follows:

  • In simple diverticulitis, localized abdominal tenderness in the area of the affected diverticula and fever

  • Left lower quadrant tenderness is most common, as most diverticula occur in the sigmoid colon

  • Right lower quadrant tenderness, mimicking acute appendicitis, can occur in right-sided diverticulitis

  • In complicated diverticulitis with abscess formation, a tender palpable mass

  • Elderly patients and some patients taking corticosteroids may have unremarkable findings, even in the presence of severe diverticulitis

Findings in patients with peritonitis due to free perforation are as follows:

  • Generalized tenderness with rebound and guarding on abdominal examination

  • The abdomen may be distended and tympanic to percussion

  • Bowel sounds can be diminished or absent

If a fistula forms, the findings vary depending on the type of fistula, as follows:

  • Women with colovaginal fistulas may present with a purulent vaginal discharge

  • Colovesicular fistulas may present as urinary tract symptoms (eg, suprapubic, flank, or costovertebral angle tenderness) or pneumaturia, and sometimes fecaluria

See Clinical Presentation for more detail.


The diagnosis of acute diverticulitis can usually be made on the basis of history and physical examination, but laboratory tests may be of help when the diagnosis is in question, as follows:

  • The white blood cell count may show leukocytosis and a left shift, but may be normal in immunocompromised, elderly, or less severely ill patients

  • A hemoglobin level is important in patients who report hematochezia

  • Electrolyte assays may be helpful in the patient who is vomiting or has diarrhea

  • Renal function is assessed prior to the administration of most intravenous contrast material

  • Liver enzyme and lipase levels may help to exclude other causes of abdominal pain

  • Urinalysis may reveal red or white blood cells in patients with a colovesicular fistula or with diverticulitis adjacent to the ureters or the bladder

  • A urine culture may distinguish sterile pyuria due to inflammation from polymicrobial infection due to fistula

  • Blood cultures should be obtained prior to the administration of empiric parenteral antimicrobial therapy in patients who are severely ill or in those with complicated disease

  • A pregnancy test must be performed in any female of childbearing age with abdominal pain

Computed tomography (CT) scanning of the abdomen is considered the best imaging method to confirm the diagnosis. Sensitivity and specificity, especially with helical CT and colonic contrast, can be as high as 97%. Possible CT findings include the following:

  • Pericolic fat stranding due to inflammation

  • Colonic diverticula

  • Bowel wall thickening

  • Soft-tissue inflammatory masses

  • Phlegmon

  • Abscesses

Other tests and procedures are as follows:

  • Contrast enema, using water-soluble medium, may be an option in mild-to-moderate uncomplicated cases of diverticulitis when CT scans do not absolutely differentiate between diverticulitis and colonic carcinoma

  • Plain abdominal radiograph series with supine and upright films can demonstrate bowel obstruction or ileus; the presence of free air can indicate bowel perforation

Clinical staging by Hinchey's classification is geared toward choosing the proper surgical procedure when diverticulitis is complicated, as follows:

  • Stage I: Diverticulitis with phlegmon or localized pericolic or mesenteric abscess

  • Stage II: Diverticulitis with walled-off pelvic, intra-abdominal, or retroperitoneal abscess

  • Stage III: Perforated diverticulitis causing generalized purulent peritonitis

  • Stage IV: Rupture of diverticula into the peritoneal cavity with fecal contamination causing generalized fecal peritonitis

See Workup for more detail.


Patients with mild diverticulitis, typically with Hinchey’s stage I disease, can be treated with the following outpatient regimen:

  • A clear liquid diet

  • 7-10 days of oral broad-spectrum antimicrobial therapy

  • Patients can advance the diet slowly as tolerated after clinical improvement occurs, which should be within 48-72 hours [1]

Single-agent or multiple-agent antibiotic regimens for outpatient therapy are equally effective, provided that they provide both anaerobic and aerobic coverage. Potential regimens include the following:

  • Ciprofloxacin and metronidazole

  • Trimethoprim-sulfamethoxazole and metronidazole

  • Moxifloxacin

  • Amoxicillin/clavulanic acid

Indications for hospital admission include the following:

  • Evidence of severe diverticulitis (eg, systemic signs of infection or peritonitis)

  • Inability to tolerate oral hydration

  • Failure of outpatient therapy (ie, persistent or increasing fever, pain, or leukocytosis after 2-3 days)

  • Immunocompromise or significant comorbidities

  • Pain severe enough to require parenteral narcotic analgesia

Inpatient treatment is as follows:

  • Initiate bowel rest and intravenous fluid hydration

  • Start broad-spectrum intravenous antibiotic coverage until culture results, if obtained, are available

  • Within 2-3 days of hospitalization, fever, pain, and leukocytosis should begin to resolve

  • The patient can then be started on a clear liquid diet and advanced as tolerated

  • If tolerating oral intake and clinically stable, the patient can be discharged to complete a 7- to 10-day course of an oral antibiotic therapy

  • Repeat the abdominal CT scan if patients do not show timely clinical improvement

  • CT–guided percutaneous drainage is indicated for peridiverticular abscesses > 4 cm in diameter

Monotherapy with beta-lactamase-inhibiting antibiotics or carbapenems is appropriate for patients who are moderately ill and require admission. Such antibiotics include the following:

  • Piperacillin/tazobactam

  • Ampicillin/sulbactam

  • Ticarcillin/clavulanic acid

  • Imipenem

  • Meropenem

Multiple-drug regimens may consist of metronidazole and a third-generation cephalosporin or a fluoroquinolone, such as the following:

  • Ceftriaxone

  • Cefotaxime

  • Ciprofloxacin

  • Levofloxacin

Pain management considerations are as follows:

  • Morphine is preferred, despite theoretical risk of affecting bowel tone and sphincters

  • Meperidine is associated with adverse effects

  • Nonsteroidal anti-inflammatory drugs and corticosteroids have been associated with a greater risk of colon perforation and should be avoided whenever possible

The classic surgical indications include some features characteristic of Hinchey’s stage III or IV disease and are as follows:

  • Free-air perforation with fecal peritonitis

  • Suppurative peritonitis secondary to a ruptured abscess

  • Uncontrolled sepsis

  • Abdominal or pelvic abscess (unless CT-guided aspiration is possible)

  • Fistula formation

  • Inability to rule out carcinoma

  • Intestinal obstruction

  • Failing medical therapy

  • Immunocompromised status

  • Extremes of age

See Treatment and Medication for more detail.



Diverticular disease includes a spectrum of conditions ranging from asymptomatic diverticular disease, to symptomatic uncomplicated diverticular disease, and complicated diverticular disease that includes acute and chronic diverticulitis. Diverticulitis is defined as an inflammation of one or more diverticula, which are small pouches created by herniation of the mucosa into the wall of the colon. Diverticulitis is generally considered a disease of the elderly, but as many as 20% of patients with diverticulitis are younger than 50 years. In its chronic form, patients may have recurrent bouts of low-grade or overt diverticulitis.

For patient education resources, see Digestive Disorders Center, as well Diverticulosis and Diverticulitis and Abdominal Pain in Adults.



Diverticula are small mucosal herniations protruding through the intestinal layers and the smooth muscle along the natural openings created by the vasa recta or nutrient vessels in the wall of the colon. True diverticulae contain all layers of the gastrointestinal wall (mucosa, muscularis propria, and adventitia) (eg, Meckel diverticulum). False diverticulae, or pseudo-diverticulae do not contain the muscular layers or adventitia, and they only involve the submucosa and mucosa. Diverticula can occur anywhere in the gastrointestinal tract but are usually observed in the colon. The sigmoid colon has the highest intraluminal pressures and is most commonly affected.

Diverticulae found in the left colon (predominantly in the sigmoid) are usually false diverticula, and they are commonly found in Western populations. Right-sided and cecal diverticulae, however, are more commonly true diverticulae, and they are usually found in people of Asian descent. Cecal diverticulae are generally rare compared to those found in the left colon. [2]

Diverticulosis is defined as the condition of having uninflamed diverticula it occurs commonly with increasing age. The cause of diverticulosis is not yet conclusive, but it appears to be associated with a low-fiber diet, constipation, and obesity. [21]

Diverticulitis is defined as an inflammation of one or more diverticula. Its pathogenesis remains unclear. Fecal material or undigested food particles may collect in a diverticulum, causing obstruction. This obstruction may result in distension of the diverticula secondary to mucous secretion and overgrowth of normal colonic bacteria. Vascular compromise and subsequent microperforation or macroperforation then ensue. Alternatively, some believe that increased intraluminal pressure [21] or inspissated food particles cause erosion of the diverticular wall, resulting in inflammation, focal necrosis, and perforation. The disease is frequently mild when pericolic fat and mesentery wall off a small perforation. However, larger perforations and more extensive disease lead to abscess formation and, rarely, intestinal rupture or peritonitis.

Fistula formation is a complication of diverticulitis. Fistulas to adjacent organs and the skin may develop, especially in the presence of an abscess. In men, colovesicular fistulas are the most common. In women, the uterus is interposed between the colon and the bladder, and this complication is only seen following a hysterectomy. The uterus precludes fistula formation from the sigmoid colon to the urinary bladder. However, colovaginal and colocutaneous fistulas can form but are uncommon.

Recurrent attacks of diverticulitis can result in the formation of scar tissue, leading to narrowing and obstruction of the colonic lumen.



United States data

Asymptomatic diverticulosis is a common condition. The incidence of diverticulosis increases with age, from less than 5% before age 40 years to greater than 65% by age 85 years.

Diverticulitis appears to be more common in patients with the largest number of diverticula; classically, 15-20% of those with diverticulosis were thought to develop diverticulitis. However, more recent findings suggest that these numbers might be less. [3] Although diverticulitis is generally considered a disease of the elderly population, as many as 20% of patients with diverticulitis are younger than 50 years.

International data

Diverticulosis occurs more frequently in Western countries and industrialized societies, and continues to increase worldwide. [22, 23] As it is less common in underdeveloped countries, diverticulitis is also less common. The reason is unclear but is presumably secondary to lifestyle and dietary factors. In fact, after adopting a more Western lifestyle, the prevalence of diverticulosis has increased in Japan. Diverticulitis involving the left colon typically affects the false diverticulae, which are usually found in Western populations. Right-sided and cecal diverticulitis (involving true diverticulae) are more prevalent in the Asian population, accounting for up to 75% of cases of diverticulitis in this group.

Race-, age-, and sex-related demographics

Genetics are believed to play a role in diverticulitis, in addition to dietary factors. Left-sided diverticula predominate in the United States. Asians, including Asian Americans, have a predominance of right-sided diverticula.

The prevalence is similar in men and women.

Diverticular disease increases in incidence with age, reaching a prevalence of greater than 65% in those older than 85 years. The mean age at presentation with diverticulitis appears to be about 60 years.

A retrospective study that followed 2127 patients with confirmed baseline asymptomatic diverticulosis over a median of 7 years found that younger patients had a considerably higher diverticulitis incidence per year of life compared with older patients, with a 24% lower risk of diverticulitis for every additional decade of life (hazard ratio = 0.66). [4, 5]

A follow-up study of 261 patients who were hospitalized for acute diverticulitis found that, compared with older patients, patients 45 years of age or younger experienced significantly more complications during hospitalization (37% vs. 12.5%) and were more likely to undergo subsequent sigmoidectomy (42.3% vs. 18.3%). The average time from index hospitalization to sigmoidectomy was approximately 18 months. Older patients were more likely to be asymptomatic after discharge. [6]



Prognosis depends on the severity of illness, the presence of complications, and any coexisting medical problems. Younger patients with diverticulitis may have more severe disease, possibly due to a delay in the diagnosis and treatment. Immunosuppressed patients have significantly higher morbidity and mortality due to sigmoid diverticulitis. [7]


Of the patients with diverticulosis, 80-85% remain asymptomatic. Approximately 5% develop diverticulitis; 15-25% of those with diverticulitis develop complications leading to surgery. These complications include abscess formation, intestinal rupture, peritonitis, and fistula formation.

Diverticulitis may be a more severe illness in patients who are immunocompromised, in patients with significant comorbid conditions, and in those taking anti-inflammatory medications. Note the following:

  • After a first occurrence of acute diverticulitis, the 5-year recurrence rate is 20%. [8]

  • Patients with diverticulitis who are managed conservatively (ie, do not receive surgery) have a recurrence rate of 20-35%.

  • In one study of 252 patients, a recurrence rate of 50% was reported after 7 years. The rate of surgery in these patients was 8% at 7 years and rose to 14% by 13 years. Recurrence rates after surgical resection range from 1-3%. The mortality rate from complications in patients with recurrent disease in this small study was 1%.

  • Another study of 337 patients hospitalized for complicated diverticulitis revealed an association of perforation and mortality in those with no prior history of diverticulitis. Of those patients with complicated diverticulitis, 53% presented with a first event.

  • These morbidity and mortality data, as well as the recurrence rates, are based on a retrospective review of relatively short-term data.

Many studies have demonstrated the significant association between obesity and the risk of developing diverticulitis. In a large prospective study of 47,228 male health professionals, men with a BMI of at least 30 kg/m2 had a higher relative risk of 1.78 for diverticulitis compared with men with a BMI of less than 21 kg/m2, after adjustment for other risk factors. [9]

Complications of diverticulitis occur more commonly with the first occurrence of acute diverticulitis versus with recurrent episodes. [8] Complications include the following:

  • Abscess

  • Intestinal fistula

  • Intestinal perforation

  • Intestinal obstruction

  • Peritonitis

  • Sepsis and septic shock

  • Diverticular bleeding (more common in diverticulosis than diverticulitis)