to avoid confusing diverticulitis-associated colitis with inflammatory bowel disease. Probiotics and

nonsteroidal anti-inflammatory medications are being explored as potentially protective agents.26,39,40

Diagnosis

Noninflammatory Diverticular Disease

Most patients with diverticulosis noted on barium study, colonoscopy, or abdominal CT scan are

asymptomatic. In patients who have vague, crampy, left lower quadrant pain in the absence of fever,

leukocytosis, or CT findings of focal inflammation, other causes of pain must also be considered.

Additional symptoms reported may include nausea, flatulence, bloating, and change of bowel habit. The

differential diagnosis includes colonic adenocarcinoma, constipation, inflammatory bowel disease, and

IBS. There are no peritoneal signs on examination, the rectal examination is unrevealing, and

proctoscopy shows no inflammation. Postinflammatory neurogenic alteration has been postulated as a

cause of visceral hypersensitivity.41–43 Nonspecific, mild mucosal inflammation and muscle spasm may

also contribute. There is considerable overlap with IBS. In addition to high-fiber modification of the diet

and bulk-forming agents such as psyllium or flaxseed, anticholinergics, analgesics, and antibiotics can be

prescribed to manage symptoms.

Hemorrhagic Diverticular Disease. Like bleeding from colonic angiodysplasia, diverticular

hemorrhage is classically asymptomatic until presentation with lower gastrointestinal hemorrhage that

can be massive. This differs from hemorrhage from inflammatory bowel disease or ischemic colitis

where there are typically symptoms before bleeding begins. A foregut source of bleeding must be

excluded by nasoenteric recovery of bilious, nonbloody aspirate or upper endoscopy. Likewise, an

anorectal source of bleeding must be excluded by examination. Localization of lower gastrointestinal

hemorrhage of any cause is necessary to help guide appropriate colon resection should that be required.

Although most cases of diverticular hemorrhage are self-limited, recurrence or failure of bleeding to

stop spontaneously determines the need for resection. Colonoscopy, tagged red blood cell scan, or, if

bleeding is brisk enough, angiography is used to localize bleeding (Fig. 69-4).

Giant Colonic Diverticula. Symptoms and signs of giant colonic diverticula may be noninflammatory

(pain, bloating, nausea, vomiting, diarrhea, abdominal tenderness and mass) or inflammatory, resulting

from perforation (pain, leukocytosis, fever, localized or generalized peritonitis).13

Inflammatory Diverticular Disease

The constellation of inflammatory signs and symptoms corresponds to the spectrum of inflammatory

complications of DD. The Hinchey classification44 categorized the severity of acute diverticulitis and has

been modified to reflect refinements of diagnosis enabled by improved CT scan quality (Table 69-2).45

The modified classification also includes manifestations of chronic inflammation such as fistula

formation and stricture/obstruction.

Symptoms of acute diverticulitis include steady, left lower-quadrant abdominal pain; fever; change in

bowel habits (constipation or diarrhea); anorexia; nausea; vomiting; bloating; and urinary tract

symptoms such as urinary frequency or retention. Examination will reveal left lower-quadrant

tenderness that may be appreciable only with deep palpation in stage 0 inflammation. In stage I or II

inflammation, focal peritoneal signs in the left lower quadrant are likely, and there may be a tender

mass. Digital rectal examination may also reveal pelvic tenderness or a tender mass in the cul-de-sac.

Generalized peritoneal signs would be expected for stage III or IV inflammation. Dehydration with

earlier stages or evolving sepsis with later stages may cause tachycardia and hypotension. Leukocytosis

is more likely with advancing stage of inflammation. The differential diagnosis includes perforated

colon cancer, acute appendicitis, perforated peptic ulcer, acute ischemic colitis, pancreatitis, and flare of

Crohn disease or ulcerative colitis. Normal serum amylase and lipase help exclude a diagnosis of

pancreatitis. Imaging studies and endoscopy help to distinguish diverticulitis from the other diagnoses.

However, active inflammation or contained perforation may limit the utility of rectal contrast CT,

barium enema studies, and endoscopy in the acute setting. Distinguishing perforated colon cancer from

DD can be especially challenging, even in the operating room.

Diverticular fistula formation represents internal drainage of an abscess (or external drainage in the

case of colocutaneous fistulas). Approximately half of diverticular fistulas are colovesical fistulas.

Women with colovesical or colovaginal fistulas have usually had a hysterectomy.46,47 Urinary tract

infection symptoms, pneumaturia, and fecaluria are common complaints. Recurrent urinary tract

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infection in elderly men should raise concern for the presence of a colovesical fistula, which is often

secondary to DD. Passage of feces or flatus from the vagina is a characteristic symptom of a colovaginal

fistula. Colocutaneous fistulas are a rare complication of DD.

Figure 69-4. Superior mesenteric arteriogram from a patient with bleeding from a right colon diverticulum. A: Early radiograph

with contrast material outlining the diverticulum (arrow). B: Late radiograph demonstrating overflow of contrast material into the

colonic lumen(arrow).

Thirteen percent of large-bowel obstructions are due to DD. The concurrent incidence of colon

carcinoma in 7% of patients with symptomatic sigmoid DD confounds diagnosis and treatment.48 CT

scan is not as reliable for distinguishing these diagnoses as colonoscopy or contrast enema studies.

Right-sided diverticulitis frequently is confused with appendicitis, and misdiagnosis is common. The

duration of symptoms is usually longer than appendicitis. Patients are usually older than those with

appendicitis (late 30s or 40s) but younger than patients with typical left-sided diverticulosis (over 50

years of age).49,50

CLASSIFICATION

Table 69-2 Modified Hinchey Classification

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Figure 69-5. Sigmoid diverticulitis with pericolic abscess(arrows).

Imaging and Diagnostic Studies for Diverticular Disease

Plain Radiographs. While seldom useful in the diagnosis of uncomplicated diverticulitis, a three-way

abdominal series that includes an upright chest radiograph, an abdominal flat plate, and a left lateral

decubitus view is useful for demonstrating free air. An ileus pattern or soft tissue mass may also be

detected.51,52

5 Computed Tomography Scan. CT scanning has revolutionized the diagnosis of acute diverticulitis

and, sometimes, by way of percutaneous abscess drainage, its treatment. The accuracy of CT scans in

the acute setting is central to the trend toward converting what formerly were surgical emergencies into

elective, often single-stage operations. Intravenous and water-soluble oral and rectal enteric contrast

should be administered. Water-soluble contrast is used to avoid barium peritonitis that may result if

barium leaks from a perforated diverticulum into the peritoneal cavity.

A CT scan can reveal the presence and extent of diverticulosis, but its real strength is characterizing

extracolonic inflammatory change. Signs of inflammation include colon wall thickening, pericolic fat

stranding, or phlegmon formation. Pericolic abscess size and location can be detected (Fig. 69-5).

Perforation is evidenced by free air; contained perforation may be identified by loculated extraluminal

pericolic air. CT more accurately demonstrates diverticular abscesses and severity of inflammation than

contrast enema studies.53 Air in the bladder or contrast in the vagina may indicate the presence of a

fistula (Fig. 69-6).

Figure 69-6. A: Computed tomography scan demonstrating air in the urinary bladder (arrow) in the presence of a colovesical

fistula secondary to diverticulitis. B: Air in the urinary bladder (small arrow) in association with a paravesical inflammatory mass

(large arrow). (Reproduced with permission from Sarr MG, Fishman EK, Goldman SM. Enterovesical fistula. Surg Gynecol

Obstet1987;164(1):41–48.)

Rao et al.54 reported a misdiagnosis rate of up to 67% for diverticulitis in patients with abdominal

pain managed without CT imaging. An alternate diagnosis is suggested by CT scan in 45% to 58% of

cases when diverticulitis is not found, including small-bowel obstruction, acute cholecystitis,

appendicitis, gynecologic disease, and primary epiploic appengitis.55 Correct preoperative diagnosis of

right-sided diverticulitis has also been enhanced by CT scanning.

Not only is CT useful for improving diagnostic accuracy, but also findings can predict failure of

medical management or risk of secondary complications following medical management.

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