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18. Benign Colon: Diverticular Disease
A. Introduction
• 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.
• It can refer to an asymptomatic state (diverticulosis) or any one
of a number of diverse combinations of infl ammatory 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
infl ammatory response, or complex infl ammatory 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).
B. Incidence
• Since the early twentieth 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, refi ned sugars, and milled fl our but low in
whole grain breads, cereals, and fruits and vegetables.
D.E. Beck et al. (eds.), The ASCRS Manual of Colon and Rectal Surgery, 379
DOI: 10.1007/978-0-387-73440-8_18, © Springer Science + Business Media, LLC 2009
380 The ASCRS Manual of Colon and Rectal Surgery
• 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.
• It is now clear that not only diverticulosis but the incidence of
related complications are increasing.
• 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.
• Overall, less than 1% of patients with diverticula will ultimately
require surgical management.
• The incidence of perforation is higher in males younger than
age 50 but in females older than 50.
C. 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 nine times higher than seen in patients with
normal colons.
• 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 defi nition of an acquired process. Thus, the
most common diverticula are acquired or pulsion diverticula.
18. Benign Colon: Diverticular Disease 381
• 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 fi ber’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.
• 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 infl ammatory conditions of the colon.
• Pain associated with diverticular disease may be related to
muscle spasm as well as infl ammation. Perforation can occur
in the absence of infl ammation and may be secondary to the
extremely high intraluminal pressure.
D. Etiology
• Pathophysiologic studies reveal that complications do not occur
until there is microperforation through the wall of a diverticulum into the pericolic tissue.
• The perforation might be small and cause a microabscess,
develop into a phlegmon, or form into a large abscess. Free
perforation occurs rarely, but fi stulization does frequently
occur, most often to the bladder.
• The original communication with the lumen of the bowel is
usually rapidly obliterated by the infl ammatory process.
• 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.
382 The ASCRS Manual of Colon and Rectal Surgery
E. 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 fi ber increase diverticular symptoms by as much
as threefold.
• Vegetables and brown bread have been shown to be protective.
• Fiber may be protective by increasing stool weight and water
content which decrease colonic segmentation pressures and
transit times.
• Fiber, through the process of fermentation, also provides shortchain fatty acids to the colonic epithelial cells, an important
source of fuel and mucosal health.
Age and Sex
• 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 fi stula.
Younger men present with fi stula 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.
• More patients at younger and younger ages are being diagnosed with diverticular disease.
Nonsteroidal Infl ammatory Drugs
• Nonsteroidal infl ammatory 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 fl ow 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.
18. Benign Colon: Diverticular Disease 383
Immunocompromise
• The use of corticosteroids is associated with a higher risk of
perforation and more severe infl ammatory complications. The
postulated mechanism is immunosuppressive and antiinfl ammatory effects hinder confi nement of perforation in its early stages.
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.
Smoking
• A recent large case-control study showed that smokers had
three times the risk of developing complications from diverticular disease than did nonsmokers. However, a large cohort
study involving more than 46,000 men in the United States did
not fi nd this same association.
Alcohol
• A Danish cohort study showed the risk of diverticulitis was
three times higher in female alcoholics than the general population and two times higher in male alcoholics. However, the
data may be biased because of dietary and smoking habits
associated with alcoholics.
F. Clinical Manifestations
Clinical Patterns
• Diverticular disease may be classifi ed 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.
384 The ASCRS Manual of Colon and Rectal Surgery
Table 18. 1. The classifi cation of diverticular disease.
Diverticulosis Asymptomatic
Diverticulitis
Noninfl ammatory Symptoms without infl ammation
Acute Symptoms with infl ammation
Simple Localized
Complicated With perforation
Chronic Persistent, low grade
Atypical Symptoms without systemic signs
Recurring, persistent Symptoms with systemic signs (may be intermittent)
Complex With fi stula, stricture, obstruction
Malignant Severe, fi brosing
• Diverticulitis can be subclassifi ed into noninfl ammatory, acute
(simple or complicated), chronic (atypical or recurring/persistent),
and complex disease.
Noninfl ammatory Diverticular Disease
• Noninfl ammatory diverticular disease describes those patients
with symptoms of diverticulitis but without associated infl ammation. The diagnosis is made at the time of elective operation when no infl ammatory changes are found in the specimen.
This has been reported in 15–35% of resections.
Acute Diverticulitis
• Acute diverticulitis is heralded by signs and symptoms of acute
infl ammation 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.
• A common classifi cation for diverticulitis with perforation was
fi rst described by Hughes et al. in 1963 and slightly revised and
popularized by Hinchey et al. in 1978. Stage I diverticulitis is a
localized pericolic or mesenteric abscess, stage II is a confi ned
pelvic abscess, stage III is generalized purulent peritonitis, and
stage IV is generalized fecal peritonitis (Fig. 18.1 ).
18. Benign Colon: Diverticular Disease 385
Fig. 18.1. Diagrammatic representation of classifi cation 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: confi ned pelvic abscess. ( c ) Hinchey stage III: gen-
eralized 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 low-grade disease.
• This is frequently associated with the presence of a phlegmon.
Complex Diverticular Disease
• Complex diverticulitis refers to disease in those patients who
manifest sequelae of chronic infl ammation including fi stula,
stricture, and obstruction.
386 The ASCRS Manual of Colon and Rectal Surgery
G. Natural History
• The natural history of diverticular disease is one of increasing risk with increasing age and a diet low in fi ber 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 fi rst 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 diffi cult to reliably estimate how
many outpatients will have recurrent episodes because outpatient data are generally not refl ective of a primary care
population.
• It has been reported that up to 10% of patients with a fi rst
episode who have responded to outpatient management will
develop recurrent or persistent symptoms which will require
hospitalization.
• The interval between acute events may be prolonged (median 5
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.
• 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.
H. Presenting Symptoms
• Patients with acute diverticulitis typically complain of left
lower quadrant abdominal pain. However, in a patient with a
18. Benign Colon: Diverticular Disease 387
redundant sigmoid colon, an infl amed 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 fl ank, 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.
• 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 fi nding, and, if present,
suggests an alternative diagnosis (e.g., cancer).
• Symptoms of dysuria or urgency suggest possible bladder
involvement because of an adjacent infl ammatory mass or a
colovesical fi stula.
• Pneumaturia, fecaluria, or passage of gas and stool through
the vagina suggest a colovesical or colovaginal fi stula,
respectively.
• Fever is common and proportional to the amount of infl ammatory response present. A high fever suggests a perforation with
abscess or peritonitis.
I. 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 refl ect
retroperitoneal and/or pelvic involvement of the infl ammatory
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.
388 The ASCRS Manual of Colon and Rectal Surgery
J. Complications
Bleeding
• Bleeding is not recognized as a feature of diverticulitis. Bleeding related to diverticulosis is discussed in Chap. 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 fi lms or
computed tomographic (CT) scan.
• Rapid progression to diffuse abdominal pain and rigidity can
be expected.
Abscess
• 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 fi stulization reported in the literature ranges
from 5 to 33%.
• Colovesical fi stula is the most common fi stula associated with
diverticular disease and diverticular disease is the most common cause of colovesical fi stula.
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