Diverticulitis is defined as macroscopic inflammation of a diverticulum that may reflect a spectrum from inflammation alone, to microperforation with localized paracolic inflammation, to macroperforation with either abscess or generalized peritonitis. Thus, there is a range from mild to severe disease. Most patients with localized inflammation or infection report mild to moderate aching abdominal pain, usually in the left lower quadrant. Constipation or loose stools may be present. Nausea and vomiting are frequent. In many cases, symptoms are so mild that the patient may not seek medical attention until several days after onset. Physical findings include a low-grade fever, left lower quadrant tenderness, and a palpable mass. Stool occult blood is common, but hematochezia is rare. Leukocytosis is mild to moderate. Patients with free perforation present with a more dramatic picture of generalized abdominal pain and peritoneal signs.
In most patients with suspected diverticulitis, a CT scan of the abdomen is obtained, especially in those with fever, leukocytosis, and signs of sepsis or peritonitis or with immunocompromise to look for evidence of complicated disease (abscess, phlegmon, perforation, fistula) and in those presenting for the first time with mild symptoms to look for evidence of diverticulitis (colonic diverticula, wall thickening, pericolic fat infiltration) and to exclude other causes of abdominal pain. Patients who respond to acute medical management should undergo complete colonic evaluation with colonoscopy or radiologic imaging (CT colonography) 4–8 weeks after resolution of clinical symptoms to exclude colorectal cancer (which may mimic diverticulitis), which is identified in 1.3% and 7.9% of patients following a diagnosis of uncomplicated or complicated diverticulitis, respectively. Endoscopy and colonography are contraindicated during the initial stages of an acute attack because of the risk of free perforation.
Diverticulitis must be distinguished from other causes of lower abdominal pain, including perforated colonic carcinoma, Crohn disease, appendicitis, ischemic colitis, C difficile–associated colitis, and gynecologic disorders (ectopic pregnancy, ovarian cyst or torsion), by abdominal CT scan, pelvic ultrasonography, or radiographic studies of the distal colon that use water-soluble contrast enemas.
Complications, such as phlegmon, abscess, perforation, peritonitis, or sepsis, develop in approximately 12% of patients with acute diverticulitis. Chronic inflammation or an untreated abscess may lead to smoldering disease (ongoing pain, leukocytosis), fistula formation that may involve the bladder, ureter, vagina, uterus, bowel, and abdominal wall or stricturing of the colon with partial or complete obstruction.
Most patients with uncomplicated disease can be managed with conservative measures. Patients with mild symptoms and no peritoneal signs may be managed initially as outpatients on a clear liquid diet for 2–3 days. Although broad-spectrum oral antibiotics with anaerobic activity commonly are prescribed, large clinical trials confirm that antibiotics are not beneficial in uncomplicated disease. A 2015 American Gastroenterological Association guideline suggests that antibiotics should be used selectively for uncomplicated disease, including patients who are immunocompromised, have significant comorbid disease, or have small pericolonic abscesses (less than 3–4 cm). Reasonable regimens include amoxicillin and clavulanate potassium (875 mg/125 mg) twice daily; or metronidazole, 500 mg three times daily; plus either ciprofloxacin, 500 mg twice daily, or trimethoprim-sulfamethoxazole, 160/800 mg twice daily orally, for 7–10 days or until the patient is afebrile for 3–5 days. Symptomatic improvement usually occurs within 3 days, at which time the diet may be advanced. Once the acute episode has resolved, a high-fiber diet is recommended.
Patients with increasing pain, fever, or inability to tolerate oral fluids require hospitalization. Hospitalization is required in patients who are immunocompromised, have significant comorbid illness, have abscesses greater than 3–4 cm, or have signs of severe diverticulitis (high fevers, leukocytosis, or peritoneal signs). Patients should be given nothing by mouth and should receive intravenous fluids. If ileus is present, a nasogastric tube should be placed. Intravenous antibiotics should be given to cover anaerobic and gram-negative bacteria. Single-agent therapy with either a second-generation cephalosporin (eg, cefoxitin), piperacillin-tazobactam, or ticarcillin clavulanate appears to be as effective as combination therapy (eg, metronidazole or clindamycin plus an aminoglycoside or third-generation cephalosporin [eg, ceftazidime, cefotaxime]). Symptomatic improvement should be evident within 2–3 days. Intravenous antibiotics should be continued for 5–7 days, before changing to oral antibiotics.
Surgical consultation and repeat abdominal CT imaging should be obtained on all patients with severe disease or those who do not improve after 72 hours of medical management. Patients with a localized abdominal abscess 4 cm in size or larger are usually treated urgently with a percutaneous catheter drain placed by an interventional radiologist. This permits control of the infection and resolution of the immediate infectious inflammatory process. Indications for emergent surgical management include generalized peritonitis, large undrainable abscesses, and clinical deterioration despite medical management and percutaneous drainage. Following recovery from complicated diverticulitis, a subsequent elective one-stage surgical resection is generally recommended to reduce recurrent episodes of complicated disease. Patients with chronic disease resulting in fistulas or colonic obstruction will require elective surgical resection.
Diverticulitis recurs in 15–20% of patients treated with medical management over 10–20 years. However, less than 5% have more than two recurrences. Among patients who have an episode of uncomplicated diverticulitis, less than 5% later develop complicated disease. Therefore, elective surgical resection is no longer routinely recommended in patients with recurrent bouts of uncomplicated disease but is individualized based on patient preference, age, comorbid disease, and frequency and severity of attacks. Diverticulosis is not associated with an increased risk of colorectal cancer.
Failure to improve within 72 hours of medical management.
Presence of significant peridiverticular abscesses (4 cm or larger) requiring possible percutaneous or surgical drainage.
Generalized peritonitis or sepsis.
Chronic complications, including colonic strictures or fistulas.
Severe pain or inability to tolerate oral intake.
Signs of sepsis or peritonitis.
CT scan showing signs of complicated disease (abscess, perforation, obstruction).
Failure to improve with outpatient management.
Immunocompromised or frail, elderly patient.
et al. Surgical treatment of diverticulitis and its complications: a systematic review and meta-analysis of randomized control trials. Surgeon. 2018 Dec;16(6):372–83.
et al. Antibiotics versus no antibiotics for the treatment of acute uncomplicated diverticulitis: review of the evidence and future directions. Surg Infect (Larchmt). 2018 Oct;19(7):648–54.
et al. Medical management of diverticular disease. Clin Colon Rectal Surg. 2018 Jul;31(4):214–6.
et al. Emergency presentations of diverticulitis. Surg Clin North Am. 2018 Oct;98(5):1025–46.
et al. Rates of elective colectomy for diverticulitis continued to increase after 2006 guideline change. Gastroenterology. 2019 Dec;157(6):1679–81.
et al; Dutch Diverticular Disease (3D) Collaborative Study Group. Long-term effects of omitting antibiotics in uncomplicated acute diverticulitis. Am J Gastroenterol. 2018 Jul;113(7):1045–52.
et al. An update on the current management of perforated diverticulitis. Am Surg. 2017 Dec 1;83(12):1321–8.