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270 A.G. Thorson and S.M. Goldberg
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.
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.
plasia, 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
11
It is theorized that such pressures lead to
12
Cellular hypertrophy, cellular hyper-
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.
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.
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
14
15
18. Benign Colon: Diverticular Disease 271
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.
shown to be protective.
ing stool weight and water content which decrease colonic
segmentation pressures and transit times.
process of fermentation, also provides short-chain fatty acids
to the colonic epithelial cells, an important source of fuel and
mucosal health.
heterocyclic amines, a factor in colon mucosal apoptosis.
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.
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.
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.
Immunocompromise
The use of corticosteroids is associated with a higher risk of
perforation and more severe inflammatory complications. The
21,22
Vegetables and brown bread have been
22
Fiber may be protective by increas-
23
Fiber, through the
24–26
Red meat has been associated with
29
Finally, more patients at younger and
30–32
29
reported
27
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
33
occur.
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
TABLE 18-1. The classification of diverticular disease
Diverticulosis Asymptomatic
Diverticulitis
Noninflammatory Symptoms without inflammation
Acute Symptoms with inflammation
Simple Localized
Complicated With perforation
Chronic Persistent, low grade
Atypical Symptoms without systemic signs
Recurring, persistent Symptoms with systemic signs (may be
Complex With fistula, stricture, obstruction
Malignant Severe, fibrosing
intermittent)
272 A.G. Thorson and S.M. Goldberg
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 con-
sider this form to be misdiagnosed Crohn’s disease.
Noninflammatory Diverticular Disease
Noninflammatory diverticular disease describes those
patients with symptoms of diverticulitis but without associated inflammation.
elective operation when no inflammatory changes are found
in the specimen. This has been reported in 15%–35% of
resections.
39
(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.
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.
39
The diagnosis is made at the time of
Some would consider this a missed diagnosis
40–42
One could conclude
42
FIGURE 18-1. 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.
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 lowgrade 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
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.
popularized by Hinchey et al.
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).
43
in 1963 and slightly revised and
44
in 1978. Stage I diverticulitis
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.
18. Benign Colon: Diverticular Disease 273
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
46
years).
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.
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
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.
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
9
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.
51
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
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.
274 A.G. Thorson and S.M. Goldberg
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.
mon 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.
52
Colovesical fistula is the most com-
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
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
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 popula-
47
tion,
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
57
cases.
colonoscopy should be delayed until resolution of the acute
episode is complete.
Generally, in the absence of an urgent indication,
18. Benign Colon: Diverticular Disease 275
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
morbidity and mortality to the safety of an elective opera-
59
In some selected cases, there may be no need for elec-
tion.
tive 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.
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.
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
Irritable Bowel Syndrome
In many ways, the distinction between chronic diverticulitis
and noninflammatory diverticular disease relies on the pathol-
59
ogist 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.
276 A.G. Thorson and S.M. Goldberg
TABLE 18-2. The Rome II criteria for IBS
IBS can be diagnosed based on at least 12 weeks (which need not be consec-
utive) in the preceding 12 months, of abdominal discomfort or pain that
has two of three of these features:
1. Relieved with defecation; and/or
2. Onset associated with a change in frequency of stool; and/or
3. Onset associated with a change in form (appearance) of stool.
Symptoms that cumulatively support the diagnosis of IBS:
1. Abnormal stool frequency (>3 stools per day or <3 stools per week)
2. Abnormal stool form (lumpy/hard or loose/watery stool)
3. Abnormal stool passage (straining, urgency, or feeling of incomplete
evacuation);
4. Passage of mucus
5. Bloating or feeling of abdominal distension
Red Flag symptoms that are not typical of IBS:
1. Pain that often awakens/interferes with sleep
2. Diarrhea that often awakens/interferes with sleep
3. Blood in stool (visible or occult)
4. Weight loss
5. Fever
6. Abnormal physical examination
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 ques-
66
tion of possible Crohn’s disease.
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,
72,73
obese,
culitis.
quently misdiagnosed preoperatively
being the most common misdiagnosis.
and have a higher incidence of right-sided diverti-
74,75
Young patients undergoing operation are fre-
72,73,76
with appendicitis
76
Historically, diverticular disease in patients younger than 50 years of age has been
described as more virulent and with more serious complica-
45,72,77–79
tions.
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 dis-
ease at first presentation
74,77–79
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
45,71
18. Benign Colon: Diverticular Disease 277
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 recom-
mendations 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 be
83
ues to become more common.
Recent evidence suggests
72,82,83
and contin-
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 =
86
.07).
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 pseudodiverticula 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.
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
91,92
Twelve
278 A.G. Thorson and S.M. Goldberg
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.
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
94–97
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.
18. Benign Colon: Diverticular Disease 279
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 twostage approach in acute cases requiring urgent or emergent
surgery.
except in the most extreme cases of medical instability.
100–102
The three-stage approach is unlikely to be used
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.
management should be drained percutaneously or transrectally as appropriate to its location (Figure 18-2).
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.
59,105
An abscess not responding to medical
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).
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
FIGURE 18-2. A A centrally located pelvic diverticular abscess. B
The same abscess after CT-guided percutaneous drainage.
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
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