Keywords

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The term “diverticular disease” of the colon represents a continuum of anatomic and pathophysiologic change within the colon related to the presence of diverticula. These changes most often occur in the sigmoid colon. The continuum can range from the presence of a single diverticulum (a sac or pouch in the wall of an organ) to many diverticula (which may be too numerous to count). It can refer to an asymptomatic state (diverticulosis) or any one of a number of diverse combinations of inflammatory symptoms, changes, and complications (diverticulitis).

Symptoms may variably result from simple physiologic changes in colonic motility related to altered neuromuscular activity in the sigmoid colon, varying degrees of localized inflammatory response, or complex inflammatory interactions leading to diffuse peritonitis and septic shock. These more complex symptoms and resulting complications arise from breaches in the integrity of the wall of one or more diverticula. Diverticula may be true, containing all layers of the bowel wall (congenital), or false, lacking the muscular layer (acquired or pulsion diverticula).

This chapter will deal with inflammatory diverticular disease and its associated complications. Bleeding from diverticular disease is discussed in Chapter 20 (Lower Gastrointestinal Hemorrhage).

Incidence

Diverticulosis was first described in the mid‐19th century as more of a curiosity than a significant disease entity. However, since the early 20th century, an increasing prevalence of the disease has been recognized in industrialized countries. The incidence increases with age and the adoption of a diet high in red meat, refined sugars, and milled flour but low in whole grain breads, cereals, and fruits and vegetables. Although the exact incidence is not well established, numerous autopsy, radiographic, and endoscopic series have shown that the incidence has increased dramatically over the past 75 years,1–4 from around 5% near the turn of the century to 50% or more by 1975.2,3

It is now estimated that the risk of developing diverticular disease in the United States approximates 5% by age 40 and may increase to more than 80% by age 80.5

This increase in observed incidence was originally attributed to new imaging techniques [the introduction of the barium enema (BE) in the early 20th century] and bias inherent to estimates based on a population presenting with symptoms requiring an investigation.6 It is now clear that not only diverticulosis but the incidence of related complications are increasing. This is exemplified by increasing costs in the treatment of diverticular disease which accounts for nearly 450,000 hospital admissions, 2 million office visits, 112,000 disability cases, and 3000 fatalities each year in the United States.7 It is estimated that costs will continue to increase as the population continues to age in the next several decades.

Proportionately few people become symptomatic from the presence of diverticula. An estimated 10%–20% of people with diverticula develop symptoms of diverticulitis, and only 10%–20% of these will require hospitalization. Of those that require hospitalization, 20%–50% will require operative intervention. The percentage of hospitalized patients requiring operation has been increasing as outpatient management becomes more common and those admitted as inpatients are more seriously ill.8 Overall, less than 1% of patients with diverticula will ultimately require surgical management.9

There is some evidence that males are more frequently affected at a younger age and females at an older age; however, significant bias may influence this impression. Young females may frequently be underdiagnosed because of confusion with gynecologic diseases in the young. Older females may be overdiagnosed because of confusion with irritable bowel syndrome (IBS). There also seems to be a dichotomy in age and sex with regard to complications of diverticular disease, particularly perforation. The incidence of perforation is higher in males younger than age 50 but in females older than 50.10

Pathophysiology

Diverticulosis is associated with high intraluminal pressures. Pressures in patients with diverticular disease have been found as high as 90 mm Hg during peak contraction. This represents a value nearly 9 times higher than seen in patients with normal colons.11 It is theorized that such pressures lead to segmentation. Segmentation refers to a process whereby the colon effectively functions as a series of separate compartments rather than a continuous tube.

The high pressures that each compartment is capable of producing are directed toward the colonic wall rather than as propulsive waves. These pressures predispose to herniation of mucosa through the muscular defects that exist where blood vessels penetrate to reach the submucosa and mucosa (vasa recta brevia). Most of these penetrations occur between the mesenteric and anti‐mesenteric tinea where, not coincidentally, most diverticula occur. As the mucosa herniates, it does so without dragging the muscular layer along, leaving the diverticula denuded of muscle and consistent with the definition of an acquired process. Thus, the most common diverticula are acquired or pulsion diverticula.

These high pressures are consistent with the sigmoid colon being the most common site of involvement. This can be explained by the law of Laplace which states that the tension in the wall of a hollow cylinder is proportional to its radius times the pressure within the cylinder. Because of segmentation, the sigmoid generates pressures so high that the effect of a smaller radius is overcome resulting in total tension in the wall of the sigmoid colon being higher than the rest of the colon and thus the sigmoid has the highest risk of diverticulum formation. It is hypothesized that at least a part of fiber's protective effect is a result of stool bulking which maintains a larger lumen, prevents segmenting contractions, and decreases high pressures.

Complementary to these theories of pathogenesis is the consistent colonic wall muscle abnormality associated with sigmoid diverticular disease. Both the circular and longitudinal muscle wall is typically thickened resulting in a reduction in the size of the lumen and a shortening of the sigmoid. The reduced lumen size may be further enhanced by secondary pericolic fibrosis.

The source of this muscular thickening is not clear. It has been observed that in the normal process of left colon peristalsis, smooth muscle in the rectosigmoid will relax in response to a stimulus, causing contraction of the colon above and the rectum below. A combination of poor diet, aging, and constipation could lead to malfunction of this relaxation response leading to a functional obstruction and the hypertrophy seen in the muscle.12 Cellular hypertrophy, cellular hyperplasia, and elastosis have all been described. Elastosis seems to precede the development of diverticulosis. It is not found in any other inflammatory conditions of the colon.

Several alternative concepts have been advanced to explain the differences in presentation of diverticular disease. Although the most common finding in diverticular disease is the muscular changes already discussed, some patients fail to demonstrate this characteristic. These patients are more likely to have diffuse diverticula throughout the colon, and are noted to have a higher incidence of bleeding. They may have an underlying connective tissue abnormality. This would explain the development of diverticula in the absence of high intraluminal pressures. The high incidence of bleeding in these patients could be related to associated inadequate vascular support in the diverticular wall.

Pain associated with diverticular disease may be related to muscle spasm as well as inflammation. Perforation can occur in the absence of inflammation and may be secondary to the extremely high intraluminal pressure.13

Etiology

The etiology of diverticulitis remains complex and relatively poorly understood. Pathophysiologic studies reveal that complications do not occur until there is microperforation through the wall of a diverticulum into the pericolic tissue. A single diverticulum experiences a change in the permeability of its isolated mucosa from physical, biochemical, or physiologic means. It is postulated that a free perforation then occurs leading to a characteristic response and progressing to varying degrees of inflammation. The perforation might be small and cause a microabscess, develop into a phlegmon, or form into a large abscess. Free perforation occurs rarely, but fistulization does frequently occur, most often to the bladder.14

The original communication with the lumen of the bowel is usually rapidly obliterated by the inflammatory process. Occasional failure of the diverticular neck to obliterate may lead to a free communication between the bowel and the peritoneal cavity with resultant fecal peritonitis. Rupture of a noncommunicating abscess may lead to purulent peritonitis.15

Low‐grade inflammation of colonic mucosa, induced by changes in bacterial microflora, can affect the enteric nervous system and alter gut function, leading to symptom development. This explanation has been postulated as a source of symptoms in IBS. The same explanation can be easily extrapolated to symptoms in diverticular disease because some patients with diverticular disease demonstrate bacterial overgrowth.16 This common source of symptoms reinforces the difficulty in sorting through the differential in patients with symptoms of bowel disease.

Recent clinical investigations have shown that disturbances in cholinergic activity may contribute to diverticular disease. Cholinergic stimulation in patients with diverticular disease leads to unsynchronized slow waves of relatively low frequency as opposed to bursts of action potentials normally associated with peristalsis.17,18 This suggests a possible role for cholinergic denervation hypersensitivity in colonic smooth muscle with upregulation of smooth muscle muscarinic receptors.19

The colon with diverticular disease has more cholinergic innervation than normal colon. In addition, there is less noncholinergic, nonadrenergic inhibitory nerve activity. This increased cholinergic activity and the relative paucity of inhibitory activity may contribute to the high intraluminal pressures and segmentation seen in the diverticular colon.20

Epidemiology

Diet

Large cohort and case‐control studies in the United States and Greece have shown that diets high in red meat and low in fruit and vegetable fiber increase diverticular symptoms by as much as threefold.21,22 Vegetables and brown bread have been shown to be protective.22 Fiber may be protective by increasing stool weight and water content which decrease colonic segmentation pressures and transit times.23 Fiber, through the process of fermentation, also provides short‐chain fatty acids to the colonic epithelial cells, an important source of fuel and mucosal health.24–26 Red meat has been associated with heterocyclic amines, a factor in colon mucosal apoptosis.27 Dietary heme has been shown to be highly cytotoxic to rat colons.28

Age and Sex

Population‐based studies have reported differences in disease presentation according to age and sex. However, it is not clear that all of these associations would remain valid in the global population of diverticular disease. McConnell et al.29 reported that female patients present with complications requiring surgery an average of 5 years later than males. Men have a higher incidence of bleeding and women a higher incidence of fistula. Younger men present with fistula and older men bleeding. Young females present with perforation whereas older females with chronic disease and stricture. Overall, patients younger than age 50 present more often with chronic or recurrent diverticulitis.29 Finally, more patients at younger and younger ages are being diagnosed with diverticular disease.

Nonsteroidal Inflammatory Drugs

Nonsteroidal inflammatory drugs (NSAIDs) have been linked to increased rates of complications related to diverticular disease. The plausible mechanism of action is indirect through known inhibition of cyclooxygenase and resultant decreased prostaglandin synthesis in the gut. Prostaglandins are important in the maintenance of mucosal blood flow and an effective colonic mucosal barrier. A direct mechanism also exists through mucosal damage caused by NSAIDs which leads to increased translocation of toxins and bacteria.30–32

Immunocompromise

The use of corticosteroids is associated with a higher risk of perforation and more severe inflammatory complications. The postulated mechanism is immunosuppressive and antiinflammatory effects hinder confinement of perforation in its early stages. The use of other immunosuppressive drugs has also been associated with such increased risks. The main risk seems to be more virulent complications once complications occur.33

Opiates

The use of opiate pain medications has been shown to increase intracolonic pressure and slow intestinal transit, both risks for complications of diverticular disease. Case series have shown high percentages of patients with perforation taking opiate analgesics.30,34

Smoking

A recent large case‐control study showed that smokers had 3 times the risk of developing complications from diverticular disease than did nonsmokers.35 However, a large cohort study involving more than 46,000 men in the United States did not find this same association.36

Alcohol

A Danish cohort study showed the risk of diverticulitis was 3 times higher in female alcoholics than the general population and 2 times higher in male alcoholics. However, the data may be biased because of dietary and smoking habits associated with alcoholics.37

Clinical Manifestations

Clinical Patterns

Diverticular disease may be classified into diverticulosis (asymptomatic) and diverticulitis (symptomatic) (Table 18‐1). Diverticulosis refers to the presence of diverticula with no related symptoms. This applies to the vast majority (80%– 90%) of patients with diverticular disease. Diverticulitis can be subclassified into noninflammatory, acute (simple or complicated), chronic (atypical or recurring/persistent), and complex disease. The term “malignant diverticulitis” has been used to describe a particularly severe form of fibrosing disease with phlegmonous inflammation extending below the peritoneal reflection, frequent fistula formation, obstruction, and high postoperative morbidity and mortality.38 Many consider this form to be misdiagnosed Crohn's disease.

Table 18‐1. The classification of diverticular disease
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Noninflammatory Diverticular Disease

Noninflammatory diverticular disease describes those patients with symptoms of diverticulitis but without associated inflammation.39 The diagnosis is made at the time of elective operation when no inflammatory changes are found in the specimen. This has been reported in 15%–35% of resections.39 Some would consider this a missed diagnosis (IBS). However, if that were always the case, then one would expect a very low resolution of symptoms after resection. In fact, although a lack of inflammatory changes in the resected specimen has been associated with lesser degrees of symptom relief, the success rate is not zero.40–42 One could conclude that resections are being performed for the right indication but the wrong pathology, delays in surgery may lead to complete resolution of previous inflammation, or noninflammatory diverticular disease is a real entity that sometimes requires surgical intervention. Careful follow‐up on the long‐term outcomes in these patients could go a long way in answering this question.

The term atypical has been applied to patients with chronic symptoms who never develop the necessary clinical and laboratory criteria to be judged as having acute diverticulitis. Up to 24% of these patients are found to lack inflammatory changes in the resected specimen thus fulfilling the criteria for noninflammatory diverticular disease. The remaining members of this group could be considered as having had acute diverticulitis based on histologic findings of inflammation. A high percentage of atypical patients (88%) become pain free at least on short‐term (12 months) follow‐up.42

Acute Diverticulitis

Acute diverticulitis is heralded by signs and symptoms of acute inflammation and may be simple (limited to the colonic wall and adjacent tissues) or complicated (with perforation). Simple acute disease is usually accompanied by systemic signs of fever and leukocytosis whereas complicated acute disease may have the added signs of tachycardia and hypotension.

Complicated acute diverticulitis can be classified according to the extent of spread of the inflammatory process. A common classification for diverticulitis with perforation was first described by Hughes et al.43 in 1963 and slightly revised and popularized by Hinchey et al.44 in 1978. Stage I diverticulitis is a localized pericolic or mesenteric abscess, stage II is a confined pelvic abscess, stage III is generalized purulent peritonitis, and stage IV is generalized fecal peritonitis (Figure 18‐1).

Figure 18‐1.
figure 1_18

Diagrammatic representation of classification system for diverticular abscesses in which the cylinders represent the colon, the circles an abscess, and the arrows perforation. A Hinchey stage I: localized pericolic or mesenteric abscess. B Hinchey stage II: confined pelvic abscess. C Hinchey stage III: generalized purulent peritonitis resulting from perforation of an abscess. D Hinchey stage IV: generalized fecal peritonitis secondary to free colonic perforation.

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Chronic Diverticulitis

Patients with chronic diverticulitis remain symptomatic (left lower quadrant pain) despite standard treatment. It is considered atypical if systemic signs never develop. With systemic signs, chronic disease may manifest as recurring, intermittent episodes of acute disease or as persistent, symptomatic low‐grade disease. This is frequently associated with the presence of a phlegmon. If resection is performed, there will be evidence of inflammatory changes within the specimen.

Complex Diverticular Disease

Complex diverticulitis refers to disease in those patients who manifest sequelae of chronic inflammation including fistula, stricture, and obstruction. Each of these complications will be addressed later in this chapter.

Natural History

The natural history of diverticular disease is one of increasing risk with increasing age and a diet low in fiber and high in red meat. The number and size of diverticula may increase with age; however, progression from one segment of bowel to another does not typically occur. The most common location for complications is in the sigmoid colon. It is unusual for complications to develop in the proximal colon after resection of the diseased sigmoid colon.

Most patients who develop a first episode of symptomatic diverticulitis have been asymptomatic until 1 month before presentation. Most will respond to bowel rest and antibiotics as an outpatient. It is difficult to reliably estimate how many outpatients will have recurrent episodes because outpatient data are generally not reflective of a primary care population. However, it has been reported that up to 10% of patients with a first episode who have responded to outpatient management will develop recurrent or persistent symptoms which will require hospitalization.45

Data are more readily available on recurrence for patients who were initially treated as inpatients. But our understanding of the natural history continues to evolve as antibiotics become more effective and inpatient status means increasingly severe disease. These changes make historical data regarding these issues of less value. In today's world, inpatients might be expected to be at a greater risk of recurrence. In fact, 10%–20% or more of these patients will develop a recurrence.45 Some, but not all of these patients, will require a second hospitalization. The interval between acute events may be prolonged (median 5 years).46 After a second hospital admission, up to 70% will continue with symptoms and more than half of those that require a third admission will do so within 1 year. The more complicated the attack, the higher the risk of recurrence.4,14,47–50

It has been estimated that up to 1% of all patients with diverticulosis will eventually require operative intervention.9 However, with an increasing overall number of individuals affected with diverticulosis and better antibiotics for managing infections, this estimate may now be too high.

Presenting Symptoms

Patients with acute diverticulitis typically complain of left lower quadrant abdominal pain. However, in a patient with a redundant sigmoid colon, an inflamed segment might present with pain in the right lower quadrant, thus complicating the differential diagnosis with appendicitis. The pain is generally constant in nature, not colicky. Radiation may occur to the back, ipsilateral flank, groin, and even down the leg. The pain may be preceded or accompanied by episodes of constipation or diarrhea. It often is progressive in nature if appropriate treatment is not instituted.

Historically, age was used as a primary determinant in distinguishing the most likely etiology of such pain. However, as increasing numbers of young people are found to have diverticular disease, the overlap between age groups has broadened and the need for diagnostic acumen has significantly sharpened. Classically, there is no prodromal epigastric pain with diverticulitis as one might expect to see with appendicitis.

Nausea and vomiting are unusual in the absence of obstruction, although secondary ileus with abdominal distention is common in more severe cases. Bleeding is not a typical associated finding, and, if present, suggests an alternative diagnosis (e.g., cancer). Symptoms of dysuria or urgency suggest possible bladder involvement because of an adjacent inflammatory mass or a colovesical fistula. Pneumaturia, fecaluria, or passage of gas and stool through the vagina suggest a colovesical or colovaginal fistula, respectively. Fever is common and proportional to the amount of inflammatory response present. A high fever suggests a perforation with abscess or peritonitis.

Occasionally, diverticular disease will present in unusual ways. These include lower extremity (hip) joint infections of a chronic nature that culture positive for enteric bacteria. Other unusual presentations include female adnexal masses on the left; inflammation/necrosis of the perineum and genitalia including complex anal fistula and Fournier's gangrene; subcutaneous emphysema of the lower extremities, neck, and abdominal wall; isolated hepatic abscess caused by enteric organisms; brain abscess caused by enteric organisms and cutaneous lesions mimicking pyoderma gangrenosum.51

Physical Findings

Patients presenting with acute diverticulitis will be tender to palpation in the left lower quadrant and left iliac region. There may be limited rigidity or localized guarding to deeper palpation. With resolution of the acute phase, palpation may reveal a mass in the left lower quadrant A positive psoas sign and/or obturator sign may reflect retroperitoneal and/or pelvic involvement of the inflammatory process.

In the event of a gross perforation with development of fecal or purulent peritonitis, the area of tenderness will spread throughout the abdomen. Guarding will become prominent and the abdominal wall will become rigid.

Complications

Bleeding

Bleeding is not recognized as a feature of diverticulitis. Bleeding related to diverticulosis is discussed in Chapter 20 (Lower Gastrointestinal Hemorrhage).

Perforation

Gross perforation can occur at two levels. If an abscess forms and then ruptures, purulent peritonitis is the result. If a large perforation occurs through the diverticulum directly into the peritoneum, fecal peritonitis is the result. Mixed fecal and purulent peritonitis may result from the rupture of an abscess which has an ongoing communication with the bowel lumen. Clinically, the presentation is that of either abrupt onset of abdominal pain for a free perforation or an abrupt exacerbation of progressive localized pain in the case of a ruptured abscess. A pneumoperitoneum is typically seen on abdominal films or computed tomographic (CT) scan. Rapid progression to diffuse abdominal pain and rigidity can be expected.

Abscess

An abscess most often results from the mechanism described above. Small abscesses less than 1 cm in diameter will frequently resolve with antibiotic therapy. Larger abscesses may require drainage. CT‐guided percutaneous drainage is the preferred approach when possible because it can convert the high risks of an urgent operation to a much safer elective operation.

Fistula

The incidence of fistulization reported in the literature ranges from 5% to 33% depending largely on the type of referral center making the report.52 Colovesical fistula is the most common fistula associated with diverticular disease and diverticular disease is the most common cause of colovesical fistula. Other relatively common fistulas associated with diverticular disease are colocutaneous, colovaginal, and coloenteric. Most patients who develop a colovaginal fistula have had a previous hysterectomy. Other fistulas have rarely been described and include colocolic, ureterocolic, colouterine, colosaphingeal, coloperineal, sigmoido‐appendiceal, colovenous, and even fistulas to the thigh (a variant of a colocutaneous fistula).

The diagnosis of a diverticular fistula is generally clinical. Many fistulas will not be directly identifiable by imaging studies. Thus, excess efforts should not be undertaken to try to radiographically or otherwise demonstrate a fistula. Gas seen in the bladder on a CT scan in a patient who has not had their urethra or bladder instrumented is the most sensitive/common finding with a colovesical fistula. The primary aim of a diagnostic workup is not to see the fistula but to determine the etiology [diverticulitis, cancer, inflammatory bowel disease (IBD), etc.] so that appropriate therapy can be initiated.

Stricture

The development of a phlegmon with repeated attacks of acute disease or long‐term persistent disease may result in a stricture. Although a relatively uncommon complication, patients will present with constipation, abdominal pain, and bloating. It is necessary to rule out carcinoma as the true cause of the stricture. Colonoscopy is the first choice to help make this distinction; however, it is not uncommon for associated bowel angulation and fixation to prevent endoscopic visualization. Contrast studies may assist the evaluation in such instances but resection may be necessary to make a diagnosis.

Obstruction

On rare occasions, complete obstruction may occur. If caused by diverticular disease, most patients will respond to initial medical management allowing an elective resection at a later date. Persistence of an obstruction may require a Hartmann's procedure or primary anastomosis with proximal diversion for management. The successful use of colonic stents to relieve obstruction secondary to diverticulitis has been described.53,54 In this setting, the stent is used as a bridge to surgery with later elective resection. However, the use of stents in benign disease is controversial. Some investigators have found a high incidence of complications leading to emergency surgery for removal of the stent and management of complications when a stent is used in this setting.55

Ureteral Obstruction

The ureter is infrequently involved with diverticular disease. When involved, it is most frequently the left ureter. Rarely diverticular disease has been reported as fistulizing to the ureter. A stricture may occur but compression is more common. This can result from retroperitoneal fibrosis secondary to diverticular inflammation. Most often, this resolves with resolution of the underlying inflammatory process although rarely ureterolysis has been advised.56

Phlegmon

A phlegmon represents an inflammatory mass. It may or may not be associated with a central abscess. A phlegmon can significantly complicate the technical aspects of resection. Many phlegmons will resolve with antibiotic therapy. If resection is planned because of recurrent episodes of disease, it is best to treat the acute phlegmon, to resolution if possible, before resection. On occasion, operation becomes necessary in the face of an acute phlegmon. This situation may be the source of some descriptions of “malignant” diverticulitis as earlier described.

Saint's Triad

Saint's triad is a described association of diverticulosis, cholelithiasis, and hiatal hernia. Although it has been suggested that the triad occurs in 3%–6% of the general population,47 it is of unknown clinical significance and likely represents the normal concomitant distribution of these common maladies.

Diagnostic Tests

Endoscopy

Endoscopy in the face of acute diverticulitis must be undertaken with extreme caution because of risk of gross perforation and decreased chance of success for complete colonic evaluation. It can provide important information before operation but will change acute management in less than 1% of cases.57 Generally, in the absence of an urgent indication, colonoscopy should be delayed until resolution of the acute episode is complete.

In the case of elective colonoscopy, the unexpected finding of acute diverticulitis (manifested as erythema, edema, pus, or granulation tissue at a diverticula opening) is distinctly unusual, occurring in just 0.8% of patients. Treatment with antibiotic therapy for such findings is generally unnecessary because follow‐up has shown that symptoms of diverticulitis do not develop after the colonoscopy.58

Abdominal X‐rays

When used, plain films of the abdomen should be done supine and upright/left lateral decubitus because the primary value is to rule out pneumoperitoneum or to assess for a possible obstruction. However, either of these two complications can also be assessed with CT scan, so in many centers, the plain abdominal film is rarely used.

Contrast Studies

Barium or water‐soluble contrast studies have proponents for their use but CT scan offers an examination of much broader scope in one evaluation making it the preferred imaging study in many centers. However, because of costs, some clinicians will use CT scan only if there is clinical suspicion of an abscess or other complicating feature for which an alternative to standard bowel rest and antibiotics might be applied. A water‐soluble contrast study can evaluate the lumen of the bowel if there is concern about distal bowel obstruction. It may be an important part of the assessment for the possible use of a stent if malignant disease is suspected.

Contrast studies have been shown to identify fistulas, most often colovaginal or coloenteric. Some clinicians prefer the anatomic view of the entire colon provided by BE because it distinguishes the extent of diverticulosis throughout the colon and can assess for stricture and colonic length. In most centers, contrast studies, if used at all, are used in a limited manner to evaluate the anatomy of the colon before an operation.

CT Scan

An important advantage to a CT scan is the ability to document diverticulitis, even if uncomplicated, when the diagnosis is in doubt. Studies using CT scan as the initial diagnostic test have shown that up to 5% of patients admitted for acute diverticulitis have been hospitalized for the incorrect clinical diagnosis.59

It has been demonstrated that CT can recognize and stratify patients according to the severity of their disease. It can distinguish uncomplicated disease with predictably short length of stay from complicated disease as defined by abscess, fistula, peritonitis, or obstruction and a predictably long length of stay. It also provides information about extracolonic pathology and anatomic variation useful for surgical planning. Early CT‐guided drainage of abscesses allows downstaging of complicated diverticulitis to convert an otherwise urgent or emergent operation with attendant increases in morbidity and mortality to the safety of an elective operation.59 In some selected cases, there may be no need for elective resection.

Ultrasonography

Transrectal ultrasound (TRUS) has been used in the evaluation of diverticular disease in conjunction with transabdominal ultrasound (TAUS). Combining TRUS with TAUS reveals complications not visualized on TAUS alone including inflamed diverticula. TRUS may be an accurate adjunct for confirming clinically suspected acute colonic diverticulitis when the rectosigmoid or perirectal tissues are affected as one might see in the case of malignant diverticulitis. It helps avoid false‐negative results and defines the severity of disease in the lower sigmoid colon better than TAUS alone. TRUS may prove to be a useful adjunct in selected cases of rectosigmoid diverticulitis and perirectal involvement by diverticular disease in centers where CT scanning is not readily available.60

Magnetic Resonance Imaging

Preliminary studies using magnetic resonance imaging colonography have shown a high correlation with CT findings in patients with diverticular disease without exposure to ionizing radiation. Three‐dimensional rendered models and virtual colonoscopy can be performed only in the nonacute setting. These comprehensive three‐dimensional models, rather than BE, may have a role in presurgical planning with concurrent assessment of the residual colon.61

Differential Diagnosis

The differential diagnosis for diverticular disease includes IBS, carcinoma, IBD, appendicitis, bowel obstruction, ischemic colitis, gynecologic disease, and urologic disease. Of these, IBS is perhaps the most difficult to differentiate in many patients.

Irritable Bowel Syndrome

In many ways, the distinction between chronic diverticulitis and noninflammatory diverticular disease relies on the pathologist whereas the distinction between noninflammatory diverticular disease and IBS relies on the diagnostic acumen of the clinician and the long‐term outcomes of resection. Because of the prevalence of diverticular disease, many patients with IBS will have concomitant diverticular disease. However, because diverticular disease is usually asymptomatic, the presence of diverticulosis in these patients will often not be the source of their symptoms but rather just a source of confusion in the differential. It is helpful to be familiar with the Rome II criteria (Table 18‐2) for the diagnosis of IBS in order to sort through this differential.

Table 18‐2. The Rome II criteria for IBS
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Colon Neoplasia

Distinguishing diverticular disease from cancer can be difficult. Imaging techniques can provide significant diagnostic assistance, but occasionally a resection is necessary to be certain. Several features of BE studies support a diagnosis of diverticular disease including preservation of the mucosa, long strictures, and the presence of diverticula. A BE is preferred by some clinicians to assess the extent of the diverticulosis and evaluate the length of the colon before resection. Although colonoscopy can frequently resolve this issue, it is not always successful because of acute angulations or narrowing of the lumen. CT evaluates the entire abdomen, can identify concurrent disease, and may give clues as to the underlying colonic pathology.

The increasing incidence of colonic neoplasia with increasing age parallels that of diverticular disease. Polyps and cancer must be considered whenever a diagnostic workup for diverticular disease is begun. Although unusual, cases of adenocarcinoma arising within a diverticulum have been reported.62 Because colonic diverticula are thin walled, containing only mucosa and serosa, early penetration by cancer is likely, leading to advanced stages with small primary lesions.

Although historically diverticular disease is not believed to have an etiologic link to colon cancer, a causal association has been identified between left‐sided colon cancer and diverticulitis. In a review of 7159 patients from the Swedish Cancer Registry, patients with diverticulitis had a long‐term increased risk of left‐sided colon cancer compared with patients with asymptomatic diverticulosis (odds ration = 4.2).63–65

Inflammatory Bowel Disease

Crohn's disease can be a particularly difficult differential to make. Both Crohn's and diverticular disease may present with similar complications including fistulas, phlegmons, and abscesses. Rectal involvement, anal disease, extracolonic signs, and bleeding suggest Crohn's. Recurrent “diverticulitis” requiring a repeat resection should always raise the question of possible Crohn's disease.66 Ulcerative colitis is rarely a significant differential problem because bleeding is not a prominent symptom of diverticulitis and a simple endoscopic examination showing inflammation within the rectum should suffice to rule out diverticular disease. In the unusual circumstance in which diverticulitis and ulcerative colitis both exist, treatment should be targeted to both entities simultaneously.

Other Colitides, Appendicitis, Gynecologic and Urologic Disease

Endoscopy can be an important adjunct in differentiating IBD, ischemic colitis, and other forms of colitis although caution must be used in the acute setting. A major advantage of the CT scan is the ability to evaluate for many of the other potential differentials including appendicitis, gynecologic and urologic disease.

Associated Conditions

There is such a high incidence of diverticulosis among patients with autosomal dominant polycystic kidney disease that some consider it an extrarenal manifestation.67 These patients undergoing renal transplantation are at particularly high risk for devastating infectious complications because of their immunocompromised state. Many transplant centers recommend prophylactic sigmoid resection in those polycystic kidney patients scheduled for transplantation with a documented history of diverticulitis.67–70

Uncommon Presentations

Diverticulitis in Young Patients

Young patients with diverticular disease are usually male,45,71 obese,72,73 and have a higher incidence of right‐sided diverticulitis.74,75 Young patients undergoing operation are frequently misdiagnosed preoperatively72,73,76 with appendicitis being the most common misdiagnosis.76 Historically, diverticular disease in patients younger than 50 years of age has been described as more virulent and with more serious complications.45,72,77–79 Many recommend that patients younger than age 50 have an elective resection after a single episode of acute disease. Recent evidence is mixed.

In some series, young people present with more severe disease at first presentation74,77–79 but less frequently have a resection at that time. Reasons for this include missed diagnoses and rapid response to therapy. With fewer resections for more complex disease, a higher percentage of young patients return with delayed complications and the appearance of more aggressive disease. Elective resection after the first episode of diverticulitis is thus advised.77–79

Others have recommended elective resections at a younger age to avoid the increased morbidity and mortality associated with urgent or emergent surgery in the elderly (0% versus 34.9%).80 Some recommendations for elective resection in the young patient are based on cost savings related to definitive surgical management versus the higher costs of ongoing medical treatment for recurring disease.81 These types of recommendations assume a high risk of recurrent disease.

There is evidence that diverticular disease in young patients is changing. It is not as rare as it used to be72,82,83 and continues to become more common.83 Recent evidence suggests there is not increased risk of complications from diverticular disease in the young.73,75,76,82–86 Based on these findings, resection after a single episode of diverticulitis is not recommended.

Data are difficult to interpret because the presentations of diverticular disease are so varied and most studies are small and retrospective with risks of unrecognized selection bias. However, it does seem that diverticular disease is more common in young patients than generally recognized. Obesity may be a risk factor, probably related to diet. Diets high in fiber are less likely to result in obesity as well as diverticular disease.

The issue of male predominance could be a result of missed diagnoses in females. Young females frequently have a gynecologic focus of attention placed on causes of abdominal pain other than diverticular disease and accentuated by the general poor recognition of the prevalence of diverticular disease in younger patients.

Current recommendations for resection are based on the predicted risk of developing a serious complication that would lead to emergency surgery with increased morbidity and mortality and frequent use of colostomy in this setting. To improve management, we must become better at predicting who is at risk for recurrent disease. Age alone does not seem to be a reliable factor. The use of CT to identify “severe” or “complex” diverticular disease seems most promising.

The risk of complications within 5 years of a first attack of diverticulitis exceeds 50% if CT shows severe diverticulitis at the initial episode.86 Mild findings on CT can be defined as localized thickening of colonic wall and inflammation of pericolic fat. Severe findings are defined as abscess and/or extraluminal air and/or extraluminal contrast. In a recent study, the incidence of remote complications was the highest (54% at 5 years) for young patients with severe diverticulitis on CT and the lowest (19% at 5 years) for older patients with mild disease. Young age and severe diverticulitis taken separately were both statistically significant factors of poor outcome (P = .007 and .003, respectively), although age was no longer significant after stratification for disease severity on CT (P = .07).86 Other studies have shown similar risks associated with complex disease on CT.85,87

Rectal Diverticula

Rectal diverticula are rare. They are typically true diverticula because they include the muscular layer of the rectum in their wall, and are frequently solitary. Inflammation can generally be managed with antibiotics.

Cecal and Right‐sided Diverticulitis

Right‐sided diverticular disease is much more common in the Far East than in the West, representing 35%–84% of diverticula in that region. Patients present an average of 20 years younger than with sigmoid diverticulitis. Classically, cecal diverticula are described as true diverticula containing all layers of the bowel wall. However, most cecal diverticula actually are false and frequently not solitary.

It is estimated that 13% of patients with cecal diverticulosis develop diverticular inflammation. Cecal diverticulitis can be graded according to the extent of the inflammation. Grade I disease refers to an easily recognizable projecting inflamed cecal diverticulum. Grade II is an inflamed cecal mass. Grade III encompasses a localized abscess or fistula. Grade IV is a free perforation or ruptured abscess with diffuse peritonitis. Cecal diverticulitis is correctly diagnosed preoperatively only 5% of the time. Appendicitis is the preoperative diagnosis in more than two‐thirds of cases.88 Intraoperative diagnosis is relatively easy with Grade I and to a lesser extent with Grade II disease. Most episodes of cecal diverticulitis presenting with Grade III or Grade IV disease are misdiagnosed intraoperatively as perforated carcinoma.

If a correct diagnosis of uncomplicated cecal diverticulitis can be made preoperatively, then antibiotics and treatment similar to left‐sided disease is appropriate. This is rare, however. When discovered intraoperatively, the options for treatment include: 1) appendectomy, nonresection of the diverticulum and postoperative antibiotic therapy; or 2) appendectomy with diverticulectomy for Grade I and identifiable Grade II disease. For not readily identifiable Grade II, Grade III, and Grade IV disease, failed treatment, or when cancer is a consideration, right hemicolectomy is the procedure of choice. Appendectomy should always accompany nonresection or diverticulectomy whenever the base of the appendix is not inflamed. This is to avoid confusion at a later date.89,90

Giant Colonic Diverticulum

Giant diverticula of the colon are rare entities associated with sigmoid diverticular disease. They are generally pseudo‐diverticula with inflammatory rather than colonic mucosal walls. They usually arise off of the antimesenteric border of the sigmoid colon. The mechanism of formation is unknown but they have been reported as large as 30–40 cm.91,92 Twelve percent occur in patients younger than age 50.

Diagnosis is by plain film of the abdomen which shows a large, solitary, gas‐filled cavity. Communication with the colon can be demonstrated with contrast enema. The differential includes congenital duplication of the colon, cholecystenteric fistula, colonic volvulus, emphysematous cholecystitis, infected pancreatic pseudocyst, pneumatosis cystoides intestinalis, Meckel's diverticulum, intraabdominal abscess, giant duodenal diverticulum, dilated intestinal loop, gastric dilatation, tuboovarian abscess, and mesenteric cyst.93

Most patients will present with vague symptoms of abdominal discomfort or pain and a soft, mobile abdominal mass. A few patients will present with one of the known complications which include perforation, sepsis, intestinal obstruction, or volvulus. The natural history is slow enlargement over time. The treatment of choice is resection of the diverticulum and adjacent colon at time of diagnosis if the patient is symptomatic.

Diverticular Disease of the Transverse Colon

This is an exceedingly rare condition. Clinical presentation most often mimics appendicitis, cholecystitis, or, less frequently, ischemic or Crohn's colitis. It is reported to occur in a younger age group than sigmoid disease and is more common in females. Treatment parallels that of sigmoid diverticulitis; however, resection is usually performed because a preoperative diagnosis is more difficult and a carcinoma frequently cannot be ruled out.

Treatment

Medical and Dietary Management

The primary management of asymptomatic diverticular disease is diet. The goal of dietary manipulation is to increase the bulkiness of stool thus increasing lumen size, decreasing transit time, and decreasing intraluminal pressures. This decreases segmentation which has been described as a significant factor in the development of diverticular disease. The ideal amount of fiber is not known; however, the recommended daily amount is 20–30 g. In general, fiber can be obtained by consuming foods high in fiber or through supplementation with one or more of a large variety of bulk laxatives. Epidemiologic evidence strongly suggests a diet high in fiber can reduce the risk of developing diverticulosis. What is less clear is whether a high fiber diet can prevent diverticulitis and its complications in patients who already have diverticulosis. Recent evidence is building in support of this concept.94–97

Acute Diverticulitis

In the absence of systemic signs and symptoms (high fever, marked leukocytosis, tachycardia, and hypotension), most patients experiencing symptoms of diverticulitis will respond to a regimen of bowel rest and antibiotics as outpatients. Diet is usually restricted to low residue or clear liquids during the acute illness but with resolution of the acute symptoms, a high fiber diet should be instituted. There is no need to restrict the ingestion of seeds or hulls because there are no data to substantiate this practice.

Appropriate antibiotics should be instituted to include coverage of Gram‐negative and anaerobic bacteria. The most predominant organisms cultured from acute diverticular abscess and peritonitis include the aerobic and facultative bacteria Escherichia coli and Streptococcus spp. The most frequently isolated anaerobes include Bacteroides spp. (B. fragilis group), Peptostreptococcus, Clostridium, and Fusobacterium spp.98

The use of anticholinergics as adjunctive therapy is based on theoretically reducing pain related to spasm and hypermotility in the sigmoid colon. Efficacy has not been proven.

Signs of more advanced disease including marked leukocytosis, high fever, tachycardia, or hypotension as well as a physical examination demonstrating more advanced intraabdominal pathology, dictate a need for inpatient management. Patients admitted for inpatient care will usually undergo a baseline CT scan which can confirm the diagnosis, rule out potential alternative diagnoses, and evaluate for complicated disease that would require a change in initial management.59

Antibiotics should be administered via an intravenous route. Generally the patient will be placed NPO (nothing by mouth) until there is evidence that clinical progress is being made and surgery will not be necessary. The diet is then gradually advanced from clear liquids and then to low residue for a variable period of time before reinstituting a high fiber diet. Symptoms should improve within 24–72 hours. Failure to improve should prompt further diagnostic workup including repeat CT scan and reevaluation of the need for alternative interventions such as operation or abscess drainage. Worsening of the patient's clinical condition, particularly progression to generalized peritonitis, should prompt urgent operative management.

Surgical Management

The surgical management of diverticular disease is replete with varied options that allow for customizing an operation to meet the needs of the individual patient. A thorough knowledge of these options and the indications for each are necessary for the surgeon managing these cases. The goal should always be to manage a complex patient in a way that will maximize the opportunity to avoid emergency surgery in favor of an elective resection.

Surgical options include primary resection with anastomosis with or without proximal diversion, resection with proximal colostomy, and oversewing of the rectal remnant (Hartmann's procedure) or mucous fistula (Mikulicz operation), simple diversion with drainage of the affected segment, diversion with oversewing of the perforation site, and, rarely, subtotal colectomy. Adjunctive measures include on‐table lavage and the option of a laparoscopic approach.

The historical discussion of these options would include the use of a three‐stage approach with diversion and drainage followed by a second operation for resection and a third operation for reestablishment of intestinal continuity. A modification of this approach includes oversewing of a visible site of perforation with an omental patch as a part of the initial operation.99 Alternatives include a two‐stage approach consisting of a Hartmann's or Mikulicz procedure followed by a second operation for reestablishment of intestinal continuity and resection with primary anastomosis, with or without proximal diversion, as a single operation. For the most part, today's discussions revolve around the relative merits of a one‐stage versus a two‐stage approach in acute cases requiring urgent or emergent surgery.100–102 The three‐stage approach is unlikely to be used except in the most extreme cases of medical instability.103,104

The following sections will discuss the applications of these approaches to the various presentations of diverticular disease including both chronic and acute forms. Special consideration will be given to the management of intraabdominal abscess.

Intraabdominal Abscess

For a patient found to have an abscess, there is much clinical evidence supporting the advantages of percutaneous drainage and the conversion of an emergent operation with its attendant increased morbidity and mortality to the relative safety of elective operation.59,105 An abscess not responding to medical management should be drained percutaneously or transrectally as appropriate to its location (Figure 18‐2).

Figure 18‐2.
figure 2_18figure 2_18

A A centrally located pelvic diverticular abscess. B The same abscess after CT‐guided percutaneous drainage.

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If drainage cannot be accomplished nonoperatively or if drainage is performed but fails to resolve systemic signs and symptoms, operation is indicated. Generally, the clinical scenario in this situation would be that of an advanced Hinchey class II. Although it is possible that intraoperative findings would support a resection with primary anastomosis with or without proximal diversion, it is more likely that a Hartmann's resection will be required.

Indications for Surgery for Acute Disease

The indications for surgery of acute disease include: 1) failure to respond to nonoperative management including a persistent phlegmon, failure of percutaneous or transrectal drainage of an abscess or increasing fever, leukocytosis, tachycardia, hypotension, signs of sepsis, or a worsening physical examination; 2) free perforation with peritonitis; and 3) obstruction that does not resolve with conservative therapy. Perforation without peritonitis may not require operation (Figure 18‐3).

Figure 18‐3.
figure 3_18

This CT scan shows a small pneumoperitoneum anteriorly. There was not physical evidence of peritonitis. This patient was managed nonoperatively with intravenous antibiotics.

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Surgical Procedures

For acute disease, the choice of operation is highly dependent on the degree of inflammatory response encountered at the time of operation. Because most acute disease can be managed nonoperatively (including the percutaneous drainage of most abscesses), the fact that an operation has become necessary suggests rather advanced pathology and the need to be conservative. In general, most Hinchey class I and some class II disease can be managed with a one‐stage procedure (resection and anastomosis) if the patient is stable, the extent of contamination is limited, and adequate bowel preparation is possible,100,106 recognizing, however, that the necessity of mechanical bowel preparation in elective colon resections has been recently questioned.107 Proximal diversion may be appropriate. Most cases of Hinchey class III and IV disease will require a two‐stage approach. Some recent evidence suggests a possible role for resection with primary anastomosis and proximal diversion in highly selected cases without gross fecal contamination.100,103

A major disadvantage of a two‐stage procedure is that 35%–45% of patients never have their colostomy closed. Women are more likely than men to not have closure.108,109 However, in patients with preexisting incontinence, a Hartman's pouch should be the procedure of choice. For patients who do not undergo closure of their stoma, it is critical that their rectal stump undergo scheduled surveillance for neoplasia as the remaining rectum has the same risk for neoplasia as the remainder of the colon.110

Complications

Predictors of complications from resection for diverticular disease include advanced age (older than 70–75 years), two or more comorbid conditions, obstipation at initial examination, the use of steroids, sepsis, obesity,103,111,112 and emergent rather than elective resection. Complications of resection include anastomotic leak and hemorrhage. The prevalence of leak from a low intraperitoneal anastomosis is generally considered to be between 2% and 5%.113 Such leaks can lead to localized or systemic sepsis without an abscess, an abscess with or without sepsis, peritonitis, and stricture. The diagnosis is dependent on a high index of suspicion on the part of the surgeon and quick response to any unusual signs of sepsis. Fever, vague abdominal pain, diarrhea, obstructive symptoms, oliguria, prolonged postoperative ileus, and sepsis all should raise the concern of a leak. The diagnosis is usually confirmed by water‐soluble contrast enema and/or CT scan with intravenous, oral, and rectal contrast.

A contained leak without an abscess can usually be managed with intravenous antibiotics and response assessed. Free extravasation of contrast failure to respond to treatment within 24–48 hours or initial severe sepsis or peritonitis requires exploration with resection of the anastomosis and proximal diversion. Repair of the anastomosis with proximal diversion is usually unsatisfactory because of the high risk for recurrent leak in this inflammatory setting. An exception would be a “pin‐hole” leak with limited inflammatory response which may be managed with repair, colonic lavage, and proximal diversion.

A leak that results in an abscess can generally be managed with percutaneous or transrectal drainage. Again, failure to respond will require laparotomy, take down of the anastomosis, and proximal diversion.

A colocutaneous fistula related to a diverticular resection will usually respond to nonoperative measures. Provided that there is no distal obstruction or foreign body and that Crohn's was not the cause of the original symptoms, spontaneous closure should be anticipated. Important steps to take to facilitate this closure include drainage of any undrained abscess, attention to nutritional needs, and appropriate wound care.

Stricture is an unusual complication related to diverticular resections unless the underlying process is Crohn's disease. In the rare instance when stricture does occur, the likely etiologies include ischemia or localized sepsis caused by confined leak. Such strictures can usually be managed by dilatation with a hydrostatic balloon or rigid proctoscopy but occasionally will require a formal restapling or resection.

Ureteral injuries are reported to occur in 1%–10% of abdominal surgeries.114 Early identification of any injury is the key to preventing significant morbidity. Although ureteral stents have not been shown to decrease the rate of injury, they do improve intraoperative identification of the ureters and the early identification of any ureteral injury.115 The decision to place ureteral stents before operation should be a function of clinical suspicion and the extent of retroperitoneal inflammation on CT scan.

General postoperative complications related to colon and rectal surgery and specifics related to the recognition and management of the specific complications mentioned above are discussed more thoroughly in Chapter 10, Postoperative Complications.

Indications for Surgery for Recurring and Chronic Disease

Patients with multiple, recurrent episodes of acute diverticulitis documented by CT scan should be considered for resection. The practice parameters of the American Society of Colon and Rectal Surgeons states that elective resection should be considered after one or two well‐documented attacks of diverticulitis depending on the severity of the attack and age and medical fitness of the patient. Patients with complicated diverticulitis should be considered for resection after one attack.116 The ultimate goal is to perform an operation electively rather than as an emergency. This requires correctly predicting those patients that are most likely to end up with a serious complication as a result of their disease. One suggestion has been to resect after one episode of diverticulitis in young patients (generally younger than 40–50 years).

It is now doubtful that age itself should be a primary consideration in the decision to operate. The literature is mixed with proponents of a more aggressive approach to the disease in young patients45,72,74,77–79,81 and those that believe age alone does not significantly increase risk.71,73,75,76,80,82–84 Other factors apply, most of which are not age related.

CT evidence of complicated or “severe” disease has been one of those criteria that have shown some promise in predicting risk. Abscess, extraluminal air, and extraluminal contrast have been associated with an increased risk of poor outcome from medical management regardless of age.85,87

Another approach is to identify specific groups of patients (other than age) who are at increased risk. Immunocompromised patients are one group that is at particular risk for poor outcome.33 The risk is attributable to a higher incidence of free perforation and more severe inflammatory complications when perforation does occur. Patients with autosomal dominant polycystic kidney disease undergoing renal transplant are a very high risk group.67–70 Prophylactic resection in such patients with a history of any diverticulitis is recommended.

Recent data have suggested that the recommendation for resection after two episodes of diverticulitis treated as an inpatient may result in too many patients undergoing resection thereby increasing the total cost of health care. Performing resection after the third episode of diverticulitis results in significant cost savings.117 Performing resection after four documented episodes rather than after two results in fewer deaths, fewer colostomies, and additional cost savings of more than $5000 per patient in those younger than 50.118 Others question the role of elective resection at all because of the high success rate of nonoperative management and the large percentage of patients presenting with urgent surgical disease that have no previous history of diverticulitis.119,120 This mirrors the experience of one of the authors (S.M.G.) in which it has not been found necessary to resect all patients with complicated disease, even after percutaneous drainage of diverticular abscesses.

Surgical Procedures

Patients undergoing resection for chronic disease will almost always be candidates for single‐stage resection with primary anastomosis. Additionally, patients returning for closure of a colostomy after initial diversion and drainage, diversion with oversew of perforation, or diversion with resection via either Hartmann's or a Mikulicz procedure, can all typically be managed with one additional operation only.

Complications

The complications related to operation for chronic disease in many ways parallel those already discussed for acute disease. In addition, a noted complication of operating on chronic disease is failure to achieve symptomatic relief. This usually results from a missed diagnosis of Crohn's disease or IBS. Any “recurrence” of symptoms after resection for chronic diverticulitis should raise the suspicion of this possibility. The presence of functional bowel symptoms preoperatively in this group of patients has been associated with poorer functional results postoperatively.121

Management of Fistula

The general principle of management is resection of the colon, usually with primary anastomosis. Treatment of the other involved organ/site varies. For the bladder, simple drainage of the bladder with an indwelling urethral catheter for 5–7 days is advised. No treatment of the vagina is required in most circumstances. Cutaneous fistulas will usually close by delay or secondary intention. Enteric fistulas require repair or resection of the involved small bowel or colon. Ureteral drainage for fistulas to the ureter, observation or hysterectomy for uterine fistulas, salpingo‐oophorectomy for fistulas to the tubes, and appendectomy would be the most common treatments for uncomplicated fistulas of the other less common varieties. If there is any question of cancer, an en bloc resection of a portion of the involved organ must accompany the resection.

Occasionally nonoperative management is appropriate when symptoms are minor or when the patient is at otherwise too great a risk for other health reasons. The use of long‐term suppressive antibiotic therapy in selected patients with colovesical fistula has been shown to eliminate symptoms and prevent complications related to the fistula until death from other causes.122

Techniques for Appropriate Resection

The practice parameters of the American Society of Colon and Rectal Surgeons set out several general recommendations regarding resection of diverticular disease. For elective resections, all thickened, diseased colon, but not necessarily the entire proximal diverticula‐bearing colon, should be removed. It may be acceptable to retain proximal diverticular colon as long as the remaining bowel is not hypertrophied. All of the sigmoid colon should be removed. When anastomosis is elected, it should be made to normal rectum and must be free of tension and well vascularized.123 The single most important predictor of recurrence after sigmoid resection for uncomplicated diverticulitis is an anastomosis to the distal sigmoid colon rather than the rectum.124

Laparoscopic Surgery

The role of laparoscopy in the management of diverticular disease is evolving. Recent data suggest decreased overall costs associated with laparoscopic resections when compared with open resections.125,126 Patients who are converted from laparoscopic to open procedures are a concern with regard to added costs but conversion rates are less than 20% in experienced centers, and are somewhat125–131 predictable128,131 and thus probably avoidable in many instances.128 Higher conversion rates are associated with more complex disease.132 Recurrence rates match those for open procedures,129,131,132 and length of stay is shorter125,126 and complications fewer.126 As data continue to accumulate, it seems that laparoscopic surgery will have a significant role in the management of diverticular disease.