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CHAPTER 82: Diverticulitis 527 is the greatest cause of increased morbidity in the pregnant woman with an acute abdomen. 8,9,77 Ovarian torsion and ectopic or heterotopic pregnancy are additional considerations. If abdominal US is nondiag nostic, consider pelvic US, CT, or MRI. Consult with the radiologist to select the most appropriate imaging study. Many radiologists avoid CT in the first trimester given teratogenic concerns of ionizing radiation. In addition, although iodinated contrast material is safe in pregnancy, avoid IV gadolinium. Children are a diagnostic challenge, particularly if they cannot ade quately verbalize their complaints. In such cases, physical examination, parallel history from the parent or guardian, and a high index of suspi cion are the keys to accurate diagnosis. Pediatric imaging should begin with US, but many centers advise early surgical consultation before any ionizing imaging if appendicitis is a consideration. REFERENCES The complete reference list is available online at www.TintinalliEM.com. Diverticulitis Autumn Graham INTRODUCTION AND EPIDEMIOLOGY Diverticular disease is increasingly common in industrialized nations, and the prevalence of diverticulosis increases with age: 5% in patients age <40 years, 30% by age 60, and >70% by age 85. 1 Based on National Emergency Department Sample records from 2006 to 2013, evolving diverticulitis prevalence and management have resulted in a 27% increase in diverticulitis-related ED visits and a 105% increase in aggregated national cost, whereas ED admissions for diverticulitis decreased from 58% to 47% and surgical management decreased by 33%. The natural history of the disease appears to be more benign than previously believed. Only 15% of patients with diverticulitis develop complicated disease. 3 Recurrence occurs in 20% to 30% of patients with diverticulitis treated conservatively. 3,4 Although surgery played a prominent role in diverticulitis management in the past, most cases of diverticulitis can be managed medically, even with recurrent episodes. In one study following 2366 Kaiser Permanente patients hospitalized with acute diverticulitis and treated nonoperatively, 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. PATHOPHYSIOLOGY 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, leads to translocation of bacteria, microperforation, and abscess or phlegmon formation. There are similar chemical and histologic changes seen in inflam matory bowel disease and irritable bowel syndrome, but no unifying mechanism has been demonstrated. 6,7 Common bacterial pathogens are anaerobes, including Bacteroides, Clostridium, and Peptostreptococcus, as well as aerobic bacteria such as Escherichia coli, Enterococcus, Pseudomonas aeruginosa, and Klebsiella . While most GI infections are CHAPTER both anaerobic and aerobic, Bacteroides fragilis and E.

emonstrated. 6,7 Common bacterial pathogens are anaerobes, including Bacteroides, Clostridium, and Peptostreptococcus, as well as aerobic bacteria such as Escherichia coli, Enterococcus, Pseudomonas aeruginosa, and Klebsiella . While most GI infections are CHAPTER both anaerobic and aerobic, Bacteroides fragilis and E. coli are the dominant bacteria isolated.8 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. NSAIDs, opioids, and steroids increase the risk of perforation. In the United States, diverticular disease is almost exclusively a leftsided 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. CLINICAL FEATURES 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 is 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 distended abdomen, to peritonitis with rebound and guarding. Urinalysis may demonstrate sterile pyuria due to inflammation of the bladder. DIAGNOSIS 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 gyne cologic 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, C-reactive protein, and urinalysis may aid in the exclusion of other disorders and prediction of diverticulitis severity. TABLE 82-1 Differential Diagnosis of Diverticulitis •  Acute  appendicitis •  Colitis—ischemic  or infectious •  Inflammatory  bowel disease (Crohn’s disease, ulcerative colitis) •  Colon  cancer •  Irritable  bowel syndrome •  Pseudomembranous  colitis •  Epiploic  appendagitis •  Gallbladder  disease •  Incarcerated  hernia •  Mesenteric  infarction •  Complicated  ulcer disease •  Peritonitis •  Obstruction •  Ovarian  torsion •  Ectopic  pregnancy •  Ovarian  cyst or mass •  Pelvic  inflammatory disease •  Cystitis •  Kidney  stone •  Renal  pathology •  Pancreatic  disease Tintinalli_Sec09_p0473-0562.indd 527 8/2/19 6:49 PM

ted  hernia •  Mesenteric  infarction •  Complicated  ulcer disease •  Peritonitis •  Obstruction •  Ovarian  torsion •  Ectopic  pregnancy •  Ovarian  cyst or mass •  Pelvic  inflammatory disease •  Cystitis •  Kidney  stone •  Renal  pathology •  Pancreatic  disease Tintinalli_Sec09_p0473-0562.indd 527 8/2/19 6:49 PM 528 SECTION 9: Gastrointestinal Disorders  IMAGING CT is the preferred imaging modality because of its ability to evaluate the severity of disease and the presence of complications. The American College of Radiology Appropriateness Criteria recommends CT of abdomen and pelvis with IV contrast and states that “oral and/or colonic contrast may be helpful for bowel luminal visualization” due to its documented sensitivities of 97% and specificities approaching 100%. Multiple retrospective and small prospective studies have shown that variable contrast strategies including no IV or PO contrast and lowdose radiation CTs have been sensitive and specific for diverticulitis. 11-13 For most patients, CT of abdomen and pelvis with IV contrast only for patients with a body mass index >20 kg/m 2 and addition of PO contrast for patients with a body mass index <20 kg/m 2 is appropriate. 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. Compression US is operator dependent and limited based on the patient’s body habitus. Sensitivity and specificity of US for diverticuli tis vary but are >80% in experienced hands. CT is preferred to detect complications. TREATMENT Treatment varies with disease severity. 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 and disposition recommendations are provided in Tables 82-2 and 82-3. Uncomplicated diverticulitis treatment is rapidly evolving. The cornerstone of treatment has been antibiotics (Table 82-2). With increased understanding of the inflammatory rather than infectious etiology of uncomplicated diverticulitis, recent studies have reported no benefit to routine antibiotic use. The 2015 American Gastroenterology Asso ciation recommends “that antibiotics should be used selectively, rather than routinely, in patients with acute uncomplicated diverticulitis” confirmed by CT. 15 These recommendations are similar to those adopted in Denmark,16 Italy,17 Germany,18 and the Netherlands.19 In the United States, this guideline recommendation was based in large part on the multicenter, randomized AVOD trial (20) in Sweden and Iceland. Of the 623 admitted patients with CT-verified, acute, leftsided diverticulitis, 309 patients were randomized to IV fluids with no antibiotics and 314 patients to IV antibiotics. Six patients (2%) who did not receive antibiotics and three patients (1%) who received antibiotics developed complications (e.g., abscess or perforation). There were no differences between the antibiotic and no antibiotic groups in symptoms at 30-day follow-up, need for emergency surgery, or median hospital stay.

tics. Six patients (2%) who did not receive antibiotics and three patients (1%) who received antibiotics developed complications (e.g., abscess or perforation). There were no differences between the antibiotic and no antibiotic groups in symptoms at 30-day follow-up, need for emergency surgery, or median hospital stay. Other retrospective and prospective studies have reported similar findings.21,22 Daniels and colleagues 23 published a multicenter, openlabel, pragmatic, randomized controlled trial of 528 patients with acute, CT-confirmed diverticulitis enrolled in one of the following strategies: (1) admission with 48 hours of IV antibiotics with con version to oral antibiotics for the remainder of a 10-day antibiotic treatment course, or (2) an outpatient observation arm for those who met criteria for outpatient treatment. No significant differences were reported between the observational versus antibiotic group in recovery time (14 vs. 12 days), complications (3.8% vs. 2.6%), recurrent disease (3.4% vs. 3.0%), surgery (3.8% vs. 2.3%), readmission (18% vs. 12%), or mortality (1.1% vs. 0.4%). These studies and expert opinion suggest that observational treat ment without antibiotics may be appropriate for CT-confirmed, uncomplicated, acute diverticulitis in immunocompetent patients with mild symptoms and without systemic infectious signs or symptoms or red flags for progression to complicated diverticulitis. Procalcitonin has been suggested as a tool to guide the use of antibiotics in diverticulitis, similar to its role in upper respiratory infection management, but more research is needed before clinical application. Dietary restriction or modification is commonly recommended, but efficacy is not clear.6 It is not necessary to limit the patient to a clear diet, but patients can be advised to eat foods as tolerated. During the acute episode, our personal recommendations also include no dairy foods, because ability to process lactate can change, and no red meat, because it is difficult to digest. TABLE 82-2 Antibiotics for Diverticulitis Outpatient 4–7 days First line Metronidazole 500 milligrams PO QID PLUS Ciprofloxacin 750 milligrams PO BID Levofloxacin 750 milligrams PO daily Trimethoprim-sulfamethoxazole (160 milligrams/ 800 milligrams) 1 double-strength tablet PO BID Cefuroxime 500 milligrams PO BID Alternate Amoxicillin-clavulanate 875 milligrams 1 tablet PO BID Moxifloxacin 400 milligrams PO daily Inpatient Moderate disease First line Metronidazole 500 milligrams IV q6h or metronidazole 1 gram IV q12h PLUS Ciprofloxacin 400 milligrams IV q12h Levofloxacin 750 milligrams IV q24h Aztreonam 2 grams IV TID Ceftriaxone 1–2 grams IV q24h Cefuroxime 1.5 grams IV q8h Alternative Ertapenem 1 gram IV q24h Piperacillin-tazobactam 3.375 grams IV q6h or 4.5 grams IV q8h Ticarcillin-clavulanate 3.1 grams IV q 6h Severe, lifethreatening First line Imipenem/cilastatin 500 milligrams IV q6h Meropenem 1 gram IV q8h Piperacillin-tazobactam 4.5 milligrams IV q8h Ticarcillin-clavulanate 3.1 grams IV q4h Alternative Ampicillin 2 grams IV q6h PLUS Metronidazole 500 milligrams IV q6h PLUS Ciprofloxacin 400 milligrams IV q12h Amikacin 15 milligrams/kg/day IV divided q12h Penicillin allergy Aztreonam 2 grams IV q6h PLUS Metronidazole 500 milligrams IV q6h Note. Adult dosing only. Dose adjustments may be required for renal and/or liver impairment. Antibiotic choice should be guided by local antibiograms and local antibiotic resistance patterns. Tintinalli_Sec09_p0473-0562.indd 528 8/2/19 6:49 PM

in allergy Aztreonam 2 grams IV q6h PLUS Metronidazole 500 milligrams IV q6h Note. Adult dosing only. Dose adjustments may be required for renal and/or liver impairment. Antibiotic choice should be guided by local antibiograms and local antibiotic resistance patterns. Tintinalli_Sec09_p0473-0562.indd 528 8/2/19 6:49 PM CHAPTER 82: Diverticulitis 529 If antibiotics are warranted, a shorter duration of antibiotics (4 to 5 days) compared to the standard antibiotic course (7 to 10 days) may be appropriate. The Infectious Diseases Society of America recommends “antimicrobial therapy for established infections should be continued until resolution of clinical signs of infection occurs, including normal ization of temperature and WBC count and return of gastrointestinal function. ” 25 The natural history of diverticulitis suggests symptom improvement in 2 to 4 days. A study of admitted patients receiving IV ertapenem found that a 4-day course of antibiotics was as effective as a 7-day course. 26 There is no proven advantage of IV antibiotics over PO antibiotics for diverticulitis. 6 Thus, for stable, immunocompetent patients with established follow-up in 2 to 4 days, a short course of antibiotics (4 to 5 days) may be appropriate. Complicated diverticulitis generally requires admission. In addi tion to bowel rest and IV antibiotics, treatments directed at specific complications are needed. Complicated diverticulitis is classified by the Hinchey classification scheme 10: 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 complica tions. Phlegmon is inflammation and infection of tissue without abscess. Patients with abscesses that measure <3 cm and phlegmon (Hinchey stage 1) are admitted for IV antibiotics and monitoring for progression. Percutaneous drainage of abscesses >3 cm have allowed many patients to forgo invasive surgical management. Initial nonoperative treatment fails in up to 20% of patients. 27 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. 10,28 DISPOSITION AND FOLLOW-UP Table 82-3 provides detailed disposition options. ED discharge is appropriate for uncomplicated diverticulitis with instructions to follow up in 2 to 3 days with a primary care provider or to return to the ED for recurring pain, fever, nausea and vomiting, or abdominal tenderness. Patients with intractable nausea or vomiting, significant comorbid diseases, 29 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 complica tions. Admit patients with complicated diverticulitis or failed outpatient management. Acknowledgments: Special thanks to Elaine Bromberek, Brandon Ruderman, Sreeja Natesan, Traci Thoureen, and Sara Scott for their assistance with this chapter. REFERENCES The complete reference list is available online at www.TintinalliEM.com.

dmit patients with complicated diverticulitis or failed outpatient management. Acknowledgments: Special thanks to Elaine Bromberek, Brandon Ruderman, Sreeja Natesan, Traci Thoureen, and Sara Scott for their assistance with this chapter. REFERENCES The complete reference list is available online at www.TintinalliEM.com. TABLE 82-3 Disposition Options for Diverticulitis Disposition Appropriate for Outpatient Management +/- antibiotics • Uncomplicated diverticulitis • Normal vital signs • Mild to moderate symptoms with mild tenderness on physical exam • No associated abdominal distention • No vomiting, able to tolerate fluids and take medications • Able to control pain with oral medications • Able to follow up with physician in 2–3 days • Able to care for self at home Inpatient Management • Complicated diverticulitis (phlegmon, abscess, perforation, fistula, stricture, obstruction) • High-risk patients High Risk of Complications and Treatment Failure Clinical Risk Factors Diagnostic Risk Factors CT Imaging Risk Factors for Progression to Complicated Diverticulitis • Age >70 years • Fever • Vomiting/Inability to tolerate PO • Poor follow-up or inability to care for self at home • Multiple comorbid conditions • Immunocompromised • Corticosteroid use • Malnutrition • Active malignancy • Chronic opiate use • Generalized abdominal pain/tenderness versus localized to left lower quadrant • Leukocytosis – WBC 11 × 109/L (sensitivity 82%, specificity 45%) • CRP >90 mg/L (sensitivity 88%, specificity 75%) • Signs of sepsis • Fluid collections (frequently anterior to rectum) • Greater length of inflamed colon (85 mm vs. 65 mm) • Inflamed diverticulum greater than 2 cm 1. Bolkenstein HE, Van de Wall BJ, Consten E, Broeders A, Draaisma W. Risk factors for complicated diverticulitis: systemic review and meta-analysis. Int J Colorectal Dis 2017; 32: 1375-1383. 2. Lorimer JW, Doumit G. Comorbidity is a major determinant of severity in acute diverticulitis. Am J Surg 193: 681, 2007. [PMID: 17512276] 3. Van Diijk S, Daniels L, Nio C, Somers I, Van Geloven A, Boermeester M. Predictive factors on CT imaging for progression of uncomplicated into complicated acute diverticulitis. Int J Colorectal Dis 2017; 32: 1693-1698. Source: Reproduced with permission from Graham AC, Carlberg DJ: Gastrointestinal Emergencies: Evidence-Based Answers to Key Clinical Questions . Switzerland: Springer Nature; 2019. Tintinalli_Sec09_p0473-0562.indd 529 8/2/19 6:49 PM