Chapter 82: Diverticulitis

Although uncommon in developing countries, diverticular disease is increasingly prevalent in industrialized nations. Radiographic and autopsy data indicate that the prevalence of diverticulosis increases with age: 5% in patients age <40 years, 30% by age 60, and >70% by age 85.^1,2 One study noted a 26% jump in hospital admissions between 1998 and 2005, particularly in patients less than 45 years of age.³

In most patients, diverticular disease is an incidental finding. The natural history of the disease appears to be quite benign. One study followed 2366 Kaiser Permanente patients hospitalized with acute diverticulitis and treated nonoperatively. Of those, 86% required no further inpatient care for diverticulitis during a 9-year follow-up period. Only 4% had a second recurrence. No patient with a second recurrence required an operation.⁴

Diverticula are small herniations at sites where the vasculature, called vasa recta, penetrates the circular muscle layer of the colon. Although true diverticula involve all layers of the colon wall, most acquired diverticula are considered false diverticula, involving only the mucosal and submucosal layers. Diverticula usually range from 5 to 10 mm, but can extend up to 20 mm in length. Diverticulitis occurs when inflammation develops and in complicated diverticulitis, leading to translocation of bacteria, microperforation, and abscess or phlegmon formation.⁵

There are similar chemical and histologic changes seen in inflammatory bowel disease and irriTable bowel syndrome, but no unifying mechanism has been demonstrated.^5,6 The most common bacterial pathogens isolated are anaerobes, including Bacteroides, Peptostreptococcus, Clostridium, and Fusobacterium as well as gram-negative rods, such as Escherichia coli.

Altered bowel motility leads to high intraluminal colonic pressures and diverticula formation. The role of diet remains unclear. Smoking and obesity increase risk for diverticulitis, and an active lifestyle is said to decrease the risk. Nonsteroidal anti-inflammatory drugs, opioids, and steroids increase the risk of perforation.⁵

In the United States, diverticular disease is almost exclusively a left-sided colon disease, specifically the descending and sigmoid colon. Right-sided disease accounts for only 2% to 5% of cases and is found predominantly in Asian populations.⁷

Classically, diverticulitis presents with left lower quadrant abdominal pain, fever, and leukocytosis. Patients with a redundant sigmoid colon, of Asian descent, or with right-sided disease may complain of right lower quadrant or suprapubic pain. The pain may be intermittent or constant and often associated with a change of bowel habits, either diarrhea or constipation. Other associated symptoms include nausea/vomiting, anorexia, and urinary symptoms. On physical examination, patients may exhibit findings ranging from mild abdominal tenderness to moderate tenderness with a tender palpable mass to peritonitis with rebound and guarding.

In sTable patients with a history of confirmed diverticulitis and a similar acute presentation, no further diagnostic evaluation is necessary unless the patient fails to improve with conservative medical treatment. If a prior diagnosis has not been confirmed or the current episode differs from the past episode, diagnostic imaging is required to exclude other intra-abdominal pathology and to evaluate for complications. The differential diagnosis of diverticulitis is extensive, including gynecologic emergencies, cancer, and inflammatory or infectious colitis (Table 82-1). Laboratory data are rarely diagnostic for diverticulitis, but liver function panels, CBC, renal panel, lipase, and urinalysis may aid in the exclusion of other disorders.

IMAGING

CT is the preferred imaging modality because of its ability to evaluate the severity of disease and the presence of complications. CT with IV and oral contrast has documented sensitivities of 97% and specificities approaching 100%.⁸ CT findings include increased soft tissue density within the pericolic fat, indicating inflammation; presence of diverticula; bowel wall thickening >4 mm; soft tissue masses, representing phlegmon; or pericolic fluid collections, representing abscesses.⁸

Compression US is operator dependent and limited based on the patient's body habitus. Sensitivity and specificity of US for diverticulitis vary but are >80% in experienced hands. CT is preferred to detect complications.⁹

Treatment varies with disease severity (Figure 82-1). Uncomplicated diverticulitis is isolated to inflammation of the diverticula with or without phlegmon or small abscess confined to the bowel wall. Complicated diverticulitis includes diverticular inflammation associated with abscess, stricture, obstruction, fistula, or perforation.

Current treatment recommendations are provided in Table 82-2.

Uncomplicated diverticulitis is treated with bowel rest (liquid diet) and oral antibiotics (Table 82-2). Dietary restriction or modification is commonly recommended, but efficacy is not clear.⁵ There is no advantage of IV antibiotics over oral antibiotics.⁵ Admission is not necessary unless there are serious comorbidities or obstacles to outpatient care. If uncomplicated diverticulitis is confirmed with CT, the success rate of ambulatory treatment is about 98%.¹⁰

There is growing interest in the treatment of uncomplicated diverticulitis without antibiotics at all, due to questions about antibiotic efficacy and antibiotic adverse effects such as allergy, nausea and vomiting, and Clostridium difficile infection.^{5,10, 11, 12}

One recent randomized controlled study in Sweden evaluated the need for antibiotics in uncomplicated diverticulitis confirmed by CT. Of the 669 patients studied, 9 patients experienced complications: three abscesses and three perforations in the nonantibiotic group and three perforations in the antibiotic group. There were no differences in outcomes between the two groups, including symptoms at 30-day follow-up, need for emergency surgery, or median hospital stay.¹⁰ The Infectious Diseases Society of America recommends a 4-day course of treatment.¹³ As of this writing, there is no consensus on the omission of antibiotics.

Complicated diverticulitis generally requires admission. In addition to bowel rest and IV antibiotics, specific treatments are directed to complications. Complicated diverticulitis is often referred to by the Hinchey classification scheme⁸: Stage 1 is small, confined pericolic or mesenteric abscesses; stage 2 is larger abscesses, extending to the pelvis; stage 3 is perforated diverticulitis and purulent peritonitis; and stage 4 refers to free perforation with fecal contamination of the peritoneal cavity.

Abscesses and phlegmon are among the most common complications. Phlegmon is inflammation and infection of tissue without abscess. Advances in percutaneous drainage of abscesses have allowed many patients to undergo less invasive treatment. Abscesses that measure <4 cm and phlegmon (Hinchey stage 1) are often admitted for IV antibiotics and do not require percutaneous drainage. Perforation has a high mortality rate, and patients need volume resuscitation, IV antibiotics, and emergent exploratory surgery. For Hinchey stage 3, the mortality rate approaches 13% and increases to 43% for Hinchey stage 4.^8,14

ED discharge is appropriate for uncomplicated diverticulitis—that is, for a patient with sTable vital signs, who is nontoxic appearing, in whom adequate analgesia can be maintained at home with oral narcotics, and with mild physical examination findings. Advise a clear diet to be advanced as tolerated, oral antibiotics, and instructions to follow up in 2 to 3 days with a primary care provider or return to the ED for recurring pain, high fevers, nausea/vomiting, or abdominal tenderness.

Patients with intracTable nausea or vomiting, significant comorbid diseases,¹⁵ poor support at home, high leukocytosis, or high fevers, as well as the elderly, the immunocompromised, and those with persistent pain should be admitted. The immunocompromised and those taking chronic steroids often present atypically and are at risk for morbidity and mortality. Patients with complicated diverticulitis or failed outpatient management should also be admitted. A failure of outpatient therapy is defined as symptoms or worsening radiographic imaging within 6 weeks of the initial episode.

YOUNG PATIENTS

Patients <40 years old comprise a small proportion of patients with diverticulitis, but their numbers are growing. This trend may correlate with the growing obesity epidemic in the United States, because young diverticulitis patients tend to be overweight. Their disease is also thought to be more virulent than that of their older counterparts, with higher rates of recurrence, complicated presentation, and surgical intervention compared to patients >50 years old. Younger patients also seem to have higher rates of readmission.^16,17

MECKEL'S DIVERTICULITIS

Meckel's diverticulum is a true congenital diverticulum that follows "the rule of 2's." It is present in approximately 2% of the population, 2 ft from the ileocecal valve, and symptomatic in 2% of patients. It generally presents with crampy abdominal pain, nausea/vomiting, and bleeding. Definitive diagnosis is often difficult, but radionucleotide imaging or CT may be helpful. Due to overlapping signs and symptoms, Meckel's diverticulitis is often confused with acute appendicitis. Treatment is surgical.

EPIPLOIC APPENDAGITIS

Epiploic appendages are small fat-filled sacs situated near the lining of the colon that can become inflamed as a result of torsion or venous thrombosis. The typical presentation is sharp abdominal pain, nausea, and vomiting. The symptoms can be confused with acute appendicitis, diverticulitis, or cholecystitis. Epiploic appendagitis is usually an incidental finding on CT and follows a benign, self-limiting course. The treatment consists of pain management and follow-up in 1 week.