1. health and fitness
2. disease

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Seminar
Diverticular disease of the colon
Neil Stollman, Jeffrey B Raskin
Colonic diverticulosis refers to small outpouchings from the colonic lumen due to mucosal herniation through the
colonic wall at sites of vascular perforation. Abnormal colonic motility and inadequate intake of dietary fibre have been
implicated in its pathogenesis. This acquired abnormality is typically found in developed countries, and its prevalence
rises with age. Most patients affected will remain entirely asymptomatic; however, 10–20% of those affected can
manifest clinical syndromes, mainly diverticulitis and diverticular haemorrhage. As our elderly population grows, we
can anticipate a concomitant rise in the number of patients with diverticular disease. Here, we review the incidence,
pathophysiology, clinical presentation, and management of diverticular disease of the colon and its complications.
Diverticulosis of the colon is quite frequent in developed
countries and prevalence rises with age. Although up to twothirds of people older than age 80 years are affected, most
remain asymptomatic. The causes of colonic diverticula
include alterations in colonic wall resistance, disordered
colonic motility, and dietary deficiencies, especially fibre.
Clinical manifestations of this disorder range from nonspecific intermittent abdominal pain to potentially lifethreatening complications such as diverticulitis or
haemorrhage. CT scanning and colonoscopy are important
in diagnosis and management. Here, we review
epidemiology, causes, clinical presentation, and management of diverticular disease of the colon.
Epidemiology
Prevalence of colonic diverticulosis is difficult to measure
because most patients are asymptomatic. In early
(1920–1940) autopsy and barium enema series, rates of
2–10% were reported.1 Data show a substantial rise in
colonic diverticula within the past few decades. Prevalence
of diverticular disease increases with age, from less than 10%
in people younger than age 40 years to 50–66% in patients
older than age 80 years.1–3 No sex differences seem to exist.
Diverticulosis has been labelled a disease of western
civilisation because of its striking geographic variability. The
disorder is rare in rural Africa and Asia, with the highest
prevalence seen in the USA, Europe, and Australia.1 Within
a given country, the incidence of colonic diverticula can vary
in ethnic groups—eg, in Chinese inhabitants of Singapore,
incidence was reported to be 0·14 cases per million
population per year versus 5·41 cases in Europeans.4
Urbanisation within a country over time can also lead to a
rise in prevalence of diverticulosis. Follow-up in Singapore
has indicated colonic diverticulosis in 19%, an increase
Lancet 2004; 363: 631–39
See Personal account page 640
Division of Gastroenterology, San Francisco General Hospital, and
University of California San Francisco, San Francisco, CA, USA
(N Stollman MD); and Division of Gastroenterology, University of
Miami School of Medicine, Jackson Memorial Medical Center,
Miami, FL, USA (Prof J B Raskin MD)
Correspondence to: Dr Neil Stollman, Division of Gastroenterology,
San Francisco General Hospital, 1001 Potrero Avenue, Suite 3-D,
San Francisco, CA 94110, USA
(e-mail: [email protected])
THE LANCET • Vol 363 • February 21, 2004 • www.thelancet.com
attributed mainly to dietary changes.5 Results of series of
symptomatic diverticular disease in Africa have shown a
rising incidence in increasingly urbanised communities.6,7
Cases of complicated diverticulitis have risen 50% in
Finland in the past two decades, an increase attributed to an
ageing population and reduced fibre consumption.8
Although much of the epidemiological research mentioned
is simply descriptive, understanding and assessing these
noted trends could yield insight into pathogenesis of the
disorder and help to predict disease course and
complications.
Pathological anatomy
Colonic diverticula typically form in parallel rows between
the taeniae coli because of weakness of the muscle wall at
sites of penetration of the vasa recta supplying the mucosa.
In European and US populations, diverticula arise mainly in
the distal colon, with 90% of patients having sigmoid colon
involvement and only 15% having right-sided
diverticula.3,9–11 This finding is in contrast to that seen in
Asian populations, in which right-sided involvement is more
prominent.5,12
Diverticula vary from solitary findings to many hundreds.
They are typically 5–10 mm in diameter but can exceed
2 cm. An entity of giant colonic diverticula has been
described with sizes up to 25 cm. Most are single, located in
the sigmoid colon, and asymptomatic, but can present with
infection, obstruction, or perforation.13
Search strategy and selection criteria
Sources of information included: authors’ published work and
research; and original research, reviews, and practice
guidelines identified by computer database search—eg,
MEDLINE, LexisNexis, The Cochrane Library, and Science
Citation Index. Most recent publications were prioritised.
Search terms included: “diverticulosis”, “diverticulitis”,
“diverticular disease”, “diverticular hemorrhage”,
“gastrointestinal bleeding”, “diverticular abscess”,
“diverticular fistula”, “colonoscopy”, “endoscopy”,
“epidemiology”, “pathogenesis”, “motility”, “fiber”,
“computerized tomography”, “CT-scanning”, “surgery”,
“laparoscopic”, “ultrasound”, “ultrasonography”, “barium
enema”, “contrast enema”, “NSAID”, and “non-steroidal
anti-inflammatory”, with Boolean operators AND and OR.
Human and animal studies in the English language were
reviewed and manually crossreferenced.
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Mesentery
Artery
Diverticulum
Contraction
Contraction
Pressure
tracing
Figure 1: Segmentation of colon by contractions producing
little bladders
Modified from reference 24 with permission of the Royal College of
Surgeons of England, 1964.
Although diverticulosis is an acquired disorder, findings
of observational studies suggest that the disease pattern—
eg, right-sided, pancolonic—might be established early on
and then remain constant, rather than increasing over time
in number and extent. In sequential studies with barium
enema, no progression of disease has generally been noted
in most patients.14 In fact, two distinct forms of
diverticulosis might exist: one discernible by muscle
thickening, mainly in the left colon, and associated with
perforation and diverticulitis; the other due to a diffuse
connective tissue abnormality, resulting in pancolonic
diverticulosis and a propensity for bleeding.15 This
possibility could, in part, account for anatomic differences
described between European and US patients and those
from Asia.
Cause and pathogenesis
Colonic wall resistance
Early gross descriptions of diverticular colons typically
noted thickening of muscle wall and shortening of the
taeniae coli, with resultant concertina-like bunching of
haustral folds. Although muscle contraction is noted,
routine histology has not generally indicated muscle
hypertrophy. Findings of electron microscopic studies have
shown that diverticular colonic walls consist of structurally
normal muscle cells but elastin deposition is amplified by
more than 200% in muscle cells in the taenia coli compared
with those without diverticula.16 Elastin is laid down in a
contracted form, resulting in shortening of the taenia coli
and bunching of circular muscle. Age-related changes in
collagen composition could have a causal role in weakening
of wall resistance. An increase in type III collagen synthesis
has been described.17,18 Further, changes in collagen
crosslinking have been shown in animal and human
models.19,20 The importance of gut wall connective tissue is
underscored by early development of diverticula in patients
with connective tissue disorders such as Marfan’s and
Ehlers-Danlos syndromes.21
Disordered motility
In the 1960s, Arfwidsson22 did manometry on patients with
or without sigmoid diverticula and showed higher resting,
postprandial, and neostigmine-stimulated luminal pressures
in diverticular patients than in controls. Painter and
colleagues23,24 confirmed these findings in response to
neostigmine or morphine in individuals with sigmoid
diverticula
(intraluminal
hypertension)
and
did
simultaneous cineradiography. Painter suggested a theory of
segmentation in which contraction of the colon causes a
632
series of discrete “little bladders” (figure 1). He proposed
that this segmentation had a physiological role in
delaying of transport and augmentation of water
reabsorption but could also generate excessively high
pressures within every bladder, favouring herniation.
This effect might be amplified by dietary fibre
deficiency.25 Subsequently, patients with symptomatic
diverticulosis have been shown to have higher motility
indices than either asymptomatic patients or healthy
controls.26 High right-sided pressures have also been
recorded in patients with right-colon diverticulosis,
suggesting that abnormal motility could also have a role
in
pathogenesis
of
proximal
diverticula.27
A
preponderance of excitatory cholinergic nerves and a
diminution of action of non-adrenergic, non-cholinergic
inhibitory nerves by nitric oxide have been noted in
diverticular colons compared with controls.28 These
findings suggest that an imbalance in usual excitatory and
inhibitory influences could favour enhanced tonicity.
Whether altered motility and intraluminal hypertension
are a cause of disease or symptoms, or an effect of same,
is uncertain.
Dietary fibre
The geographic variability of diverticular disease and
correlation with a western diet have long suggested a
dietary factor as fundamental in pathogenesis of the
disorder. Burkitt and Painter1 were the most eloquent
proponents of this theory, labelling diverticulosis a
deficiency disease that, like scurvy, could be avoided
with dietary changes. They recorded transit times and
stool weights from more than 1200 individuals in the
UK and rural Uganda.29 The UK patients, eating a low
fibre diet, had transit times of about 80 h and mean stool
weights of 110 g/day. By contrast, rural Ugandans,
eating very high fibre diets, had times of 34 h and
weights of more than 450 g/day. The longer transit time
and smaller stool volumes were thought to increase
intraluminal pressure, predisposing to diverticular
herniation. As reasonable as this hypothesis seems,
results of studies in western populations comparing
transit times and stool volumes in patients with and
without diverticular disease have failed to show
significant differences. Nonetheless, corroborative data
in animals do exist, most notably in rats fed diets of
various fibre content throughout their lifespan.30 45% of
rats on the lowest fibre diet developed diverticula
compared with only 9% of those fed the highest fibre
diet. Furthermore, in another animal model, high fibre
diets protected against collagen crosslinking and were
associated with reduced frequency of diverticulosis.19
Uncomplicated diverticulosis
Most patients, perhaps 75–80%, with anatomical
diverticulosis will remain asymptomatic throughout their
lifetime. Of the few who develop complications,
diverticulitis—and its difficulties such as abscesses,
fistulas, or obstruction—is the most usual manifestation,
followed by diverticular haemorrhage, both of which are
addressed below.
The asymptomatic patient
Asymptomatic diverticular disease is frequently an
incidental finding during assessment of a patient for
another reason, such as routine screening for colon
cancer. No treatment or follow-up needs to be offered to
this large population, most of whom will remain
asymptomatic, although findings of one study suggested a
possible prophylactic benefit of a high-fibre diet. In a
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prospective study of 51 529 US male health professionals
followed up for more than 4 years, 385 new cases of
symptomatic diverticular disease were identified.31 A
significant inverse association was recorded between
dietary fibre intake and risk of development of clinically
evident diverticular disease. Insoluble fibre from fruits
and vegetables was noted to be more protective than
cereal fibres.32 These results provide support for a recommendation that patients with asymptomatic diverticular
disease might benefit from increasing their fruit and
vegetable fibre intake, a stance endorsed by the American
Dietetic Association.33
The symptomatic patient
Patients can present with non-specific abdominal
complaints—eg, lower abdominal pain, usually leftsided—and subsequently be shown to have diverticulosis
coli; a causal relation is sometimes difficult to establish.
Such patients do not usually manifest signs of inflammation, such as pyrexia or neutrophilia, which could
indicate diverticulitis. Pain is generally exacerbated by
eating and diminished with defecation or flatus, which
suggests colonic wall tension due to raised intraluminal
pressure. Patients might also report other symptoms such
as bloating or constipation. Assessment can indicate
fullness or mild tenderness in the left lower quadrant,
but frank rebound or guarding should be absent.
A guaiac-positive stool in this setting should never be
attributed to diverticulosis without complete colonic
assessment. Findings of laboratory studies should be
normal.
Diagnostic modalities
For years, barium enema was the standard investigation
in diverticulosis patients, and although it provides
information on number and location of colonic
diverticula, it cannot discern clinical relevance. However,
inaccurate findings have been reported in nearly a third
of patients with diverticulosis.34 This disorder has, in the
past, been regarded as a contraindication to colonoscopy
for fear of causing a perforation.35,36 Further data and
extensive clinical experience, however, have shown that
colonoscopy is safe in this population, although the
diverticular colon can be difficult to examine because of
spasm, luminal narrowing, and fixation.37
Treatment
Brodribb38 did a randomised double-blind trial of a highfibre diet in 18 patients with symptomatic diverticular
disease. A significant placebo effect was noted at
1 month; however, by 3 months, a significant reduction
in bowel symptoms was seen in patients on the high-fibre
diet. These findings suggest that patients should
gradually increase their dietary fibre over weeks, and be
aware that their symptoms might initially worsen before
they improve, which could take months. In a subsequent
study,39 no improvement in symptom endpoints was
reported despite a decline in transit times and increases
in stool weight and frequency. Despite these conflicting
data, some amelioration of symptoms in patients with
uncomplicated disease can be reasonably expected with a
high-fibre diet.
Hypermotility of the diverticular colon suggests that
anticholinergic or antispasmodic drugs might improve
symptoms by diminishing muscular contraction.
Nonetheless, no adequately controlled therapeutic trials
have shown a benefit. No rationale exists for use of
antibiotics or narcotic analgesics in uncomplicated
diverticular disease.
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Complicated diverticular disease
Diverticulitis
Diverticulitis is the most usual clinical complication of
diverticular disease, affecting 10–25% of patients with
diverticula.3 The process by which diverticulitis arises has
been likened to that of appendicitis, with a diverticulum
becoming obstructed by inspissated stool in its neck.40
This faecalith abrades the mucosa of the sac, causing
inflammation and expansion of usual bacterial flora, with
diminished venous outflow and localised ischaemia.
Bacteria may breach the mucosa and extend the process
through the full wall thickness, ultimately leading to
perforation.41 Extent and localisation of the perforation
will establish its clinical behaviour. Microperforations can
remain contained by pericolic fat and mesentery and cause
small pericolic abscesses. Large perforations can result in
an extensive abscess, which could continue around the
bowel wall and form a large inflammatory mass or extend
to other organs. Free perforation into the peritoneum
causing frank peritonitis can be life-threatening but is rare.
Clinical features
People with diverticulitis generally present with left lower
quadrant pain, indicating the propensity for this disorder
to arise in the sigmoid colon in western countries,
although individuals with redundant sigmoid colons can
manifest suprapubic or right-sided pain. Asian patients
have predominantly right-sided diverticula and will usually
present with right lower quadrant pain.42 Pain may be
intermittent or constant and is sometimes associated with
a change in bowel habits.43 Haematochezia is rare,
although anorexia, nausea, and vomiting can arise.
Physical examination usually discloses localised tenderness
and, occasionally, a palpable mass. Bowel sounds are
typically depressed but can be normal in mild cases or
enhanced in the presence of obstruction. Rectal
examination may reveal tenderness or a mass, especially
with a low-lying pelvic abscess. Fever is present in most
patients, although hypotension and shock are unusual.
White blood cell count is sometimes raised.43
The differential diagnosis of this presentation includes
acute appendicitis, especially in Asian patients or those
with redundant sigmoid colons.42 Aphthous ulcers,
anorectal involvement, and chronic diarrhoea suggest a
possible diagnosis of Crohn’s colitis. Colon carcinoma,
like diverticulosis, affects colons of ageing westerners, and
a causal relation has been postulated. Most probably,
colon cancer and diverticulosis are both results of the same
environmental effects, mainly dietary. Chronic symptoms
of weight loss or bleeding should raise suspicion for
carcinoma. Surgical investigation and resection could be
necessary to make a precise diagnosis. In uncomplicated
cases, elective colonoscopy after acute inflammation has
resolved will allow for exclusion of malignant disease.
Elderly people with diverticulosis are also at risk for
ischaemic colitis. Features helpful to differentiate between
these disorders include presence of thumbprinting on
abdominal radiographs and haematochezia, both
suggesting ischaemia. Gynaecological disorders, such as
ruptured ovarian cysts, ovarian torsion, ectopic pregnancy,
or pelvic inflammatory disease, can resemble acute
diverticulitis in female patients. Pelvic ultrasound can be
helpful in obtaining an accurate diagnosis. Other forms of
colitis, such as pseudomembranous or amoebic, can also
mimic diverticulitis.
Diagnostic modalities
Most patients with diverticulitis present with signs and
symptoms sufficient to justify clinical diagnosis and
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Figure 2: Barium enemas of manifestations of diverticulitis
(A) Acute diverticulitis with oedema (arrow) of the bowel wall. (B) Intramural sinus tract (arrow) in acute diverticulitis. (C) Confined perforation or abscess
(arrow) in acute diverticulitis. All figures courtesy of Javier Casillas.
institute empiric treatment, although a thorough physical
examination and basic laboratory studies, such as white
blood cell count, should be done in patients coming to
clinical attention. Further studies should be reserved for
individuals in whom diagnosis remains uncertain,
response to empiric treatment is suboptimal, or a
complication is suspected.
Chest and abdominal radiographs should generally be
done in patients with clinically significant abdominal pain.
A chest radiograph taken while the patient is upright can
aid detection of pneumoperitoneum and help to assess
cardiopulmonary status. Abdominal radiographs can show
abnormal findings in 30–50% of patients,44,45 which
include small or large bowel dilation or ileus,
pneumoperitoneum, bowel obstruction, or soft-tissue
densities suggesting abscesses.
Contrast enemas—once the diagnostic standard—are
limited by the fact that diverticulitis is mainly an
extraluminal process. If they are to be undertaken, watersoluble contrast material should be used and a lowpressure single-contrast study done. Findings deemed
highly suggestive of diverticulitis include extravasated
contrast material outlining an abscess cavity, intramural
sinus tract, or fistula (figure 2).9,46 Absence of any
diverticula should provoke reconsideration of the
diagnosis. In retrospective analyses, contrast enema has
been shown to have a sensitivity of 62–94%, with falsenegative results in 2–15%.47,48
CT scanning has an increasing role in diagnosis,
and should be regarded as the diagnostic procedure of
choice. Abdominal and pelvic scanning is done with
intravenous, oral, and rectal contrast. Criteria suggestive
of diverticulitis include pericolic infiltration of fatty tissue,
colonic wall thickening, and abscess formation (figure 3).
In many trials comparing CT with barium enema in
suspected diverticulitis, sensitivities for CT of 93–98%
and specificities of 75–100% have been consistently
reported, significantly more accurate than contrast
enemas.46,49–51
Because of risk of perforation from either the device or
air insufflation, endoscopy is generally avoided in initial
assessment of the patient with acute diverticulitis. Its
use should be restricted to situations in which diagnosis
of diverticulitis is unclear. In such cases, limited
sigmoidoscopy with minimum insufflation can be helpful
to exclude other diagnoses, such as inflammatory,
infectious, or ischaemic colitis.
Treatment
Need for admission is the initial decision to be made in
uncomplicated diverticulitis, which is based on patient’s
presentation, their ability to tolerate oral intake, severity
of illness, comorbid disease, and adequate outpatient
support. Outpatients should be treated with a clear liquid
diet and a broad-spectrum oral antibiotic with activity
against anaerobes and gram-negative rods (in particular,
Escherichia coli and Bacteroides fragilis).52 Symptomatic
improvement should generally be evident within 2–3 days,
at which time diet can be slowly advanced. Antibiotic
treatment should be continued for 7–10 days. Patients
needing admission should have clear liquids or nothing by
mouth and intravenous fluids. Intravenous antibiotics
should be started, aimed mainly at colonic anaerobic and
gram-negative flora.52 Improvement of symptoms should
Figure 3: CT scans of manifestations of diverticulitis
(A) Contained abscess (arrow) in severe sigmoid diverticulitis. (B) Large air-containing abscess (arrow) in subacute diverticulitis. (C) Large diverticular
abscess (arrow) with penetration into retroperitoneal structures and extending through abdominal wall into subcutaneous tissue. All figures courtesy of
Javier Casillas.
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be expected within 2–4 days, at which point diet can be
advanced. If improvement continues, patients may be
discharged to complete a 7–10 day oral antibiotic course.
Failure of conservative medical treatment warrants a
diligent search for complications, consideration of
alternative diagnoses, and surgical consultation. Most
patients admitted with acute diverticulitis will respond to
conservative treatment, but 15–30% will need surgery
during that time.9,48,53 Free perforation with generalised
peritonitis, although uncommon, carries a high mortality
rate (up to 35%) and needs urgent surgical intervention.9,48
For most patients who respond well to conservative
treatment, an important clinical question subsequently
revolves around likelihood of recurrence and role of
prophylactic surgical resection. Risk of recurrent
symptoms after an attack of acute diverticulitis has been
reported between 7% and 45%; a third is a reasonable
approximation.9,48,53 Recurrent attacks are less likely to
respond to medical treatment and have a high mortality
rate;48,53 thus, most authorities agree that elective resection
is indicated after two attacks of uncomplicated
diverticulitis.54–56 The risk-benefit analysis of such an
approach must be tailored with consideration of severity
and responsiveness of the episode, general health of the
patient, and risk of subsequent occurrence. Risk of
resection is an evolving factor, with reports of increasingly
favourable experiences with laparoscopic resections for
diverticular disease.57–62 This approach might reduce the
threshold for resection in some patients by lowering
operative morbidity. However, some patients will still have
symptoms after surgical resection.
Diverticulitis in special situations
Diverticulitis is seen in about 2–5% of people younger
than 40 years old,9,53 mainly in males.9,63,64 Disease is more
virulent in young patients, with 66–88% needing urgent
surgery during their initial attack, with a high risk of
recurrences or complications.9,63,65,66 Obesity can also be an
important risk factor in young people.67 For these reasons,
and because of the low operative risk of an elective
procedure in an otherwise healthy young patient, resection
is generally indicated after one well-documented episode
of uncomplicated diverticulitis.48,54 Others, however, have
questioned this assertion.56,68,69
Immunocompromised patients with diverticulitis may
present with more subtle signs and symptoms than those
who are immunocompetent and represent a difficult
diagnostic challenge. They are less likely to benefit from
medical treatment and have a higher rate of free
perforation, need for surgery, and postoperative mortality
than non-compromised patients.70,71 Because of this high
risk, some authorities have advocated elective resection
after one episode in an immunosuppressed individual.54
Complicated diverticulitis
Abscess
When perforation of a diverticulum takes place, a localised
phlegmon initially develops; further spread can lead to
formation of large local or distant abscesses. Clinical signs
suggesting abscess formation include a tender mass on
investigation or persistent fever despite an adequate trial
of antibiotics. When an abscess is suspected, CT scanning
is the best modality for making the diagnosis and following
its course.
Small pericolic abscesses can generally be treated
conservatively with continued antibiotics and bowel
rest.56,72 In patients in whom surgery is needed, a singlestage resection and anastomosis can generally be done.
For those with distant or unresolving abscesses, drainage
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is indicated. Surgery was previously the main option, but
CT-guided percutaneous drainage of abdominal abscesses
is now used in preference when feasible. The advantage of
percutaneous catheter drainage is rapid control of sepsis
and patient stabilisation. Further, drainage might eliminate
need for a two-stage procedure with interval colostomy,
instead allowing temporary palliative drainage and
subsequent single-stage resection.73,74
Fistulas
When a diverticular phlegmon or abscess extends or
ruptures into an adjacent organ, fistulas can arise, the most
typical being colovesicular.75 Such fistulas have a two to one
male predominance, attributable to protection of the
bladder by the uterus and 50% rate of hysterectomy in
female patients with colovesical fistulas. Pneumaturia and
faecaluria are suggestive signs.76 Cystoscopy, cystography,
and contrast radiographs or methylene blue studies can
show fistula tracts. Single-stage operative resection with
fistula closure can be undertaken in most patients.75,76
Colovaginal fistulas are the next most frequent,
representing about 25% of all cases.75 Passage of stool or
flatus via the vagina is pathognomonic. Frequent vaginal
infections or copious discharge should prompt consideration of a colovaginal fistula. Treatment is surgical
resection of the diseased colon with repair of the contiguous
organ.56 Coloenteric, colouterine, coloureteral, and
colocutaneous fistulas arise much less typically.
Obstruction
During an episode of acute diverticulitis, partial colonic
obstruction can happen because of relative lumenal
narrowing from pericolic inflammation or compression
from abscess formation. Colonic pseudo-obstruction can
also take place. Acute diverticulitis might cause small bowel
obstruction or ileus if a loop of small intestine becomes
incorporated into the inflammatory mass. These
presentations usually improve as inflammation subsides
with effective treatment; failure to do so should prompt
surgical consultation.
Recurrent episodes of diverticulitis, sometimes subclinical, can initiate progressive fibrosis and stricturing of
the colonic wall without persisting inflammation.
Ultimately, high-grade or complete obstruction can
happen, needing surgery. An insidious presentation with
non-specific symptoms is typical. Generally, a stricture with
uncertain cause is identified on barium enema. The
important issue is to distinguish between a diverticular
stricture and a stenosing neoplasm. Doctors should attempt
to make this differentiation by colonoscopy with biopsy, but
this procedure is not always possible.77 Strictures in which
malignant disease cannot be excluded should undergo
surgical en bloc resection. A trial of endoscopic treatment
with balloon dilation can be attempted in patients in whom
neoplasm is judged sufficiently excluded.78–80 Early work
with colonic metal stents has suggested that they might
have a role in colonic obstruction due to diverticular
disease. Stenting can provide temporary decompression,
allowing for bowel preparation and subsequent single-stage
resection without diversion.81,82
Haemorrhage
Important lower gastrointestinal bleeding can be caused
by diverticula, vascular ectasias, colitis, or neoplasms.10,83–85
Diverticular sources have been reported to be the most
typically identified cause, accounting for greater than 40%
of lower gastrointestinal bleeding episodes.86,87 Severe
haemorrhage can arise in 3–5% of patients with
diverticulosis.10,88,89 Despite the fact that most diverticula
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Figure 4: Endoscopic pictures of diverticulum
(A) Diverticulum with visible vessel. (B) Oozing during epinephrine injection. (C) Diverticulum post injection. All photos courtesy of Francisco C Ramirez.
are in the left colon in western individuals, the site of
bleeding may more often be located in the proximal
colon.10,88,90–93
Pathophysiology
Microangiography on resected specimens from patients
with bleeding diverticula shows intimal thickening and
medial thinning of the vasa recta as it courses over the
dome of the diverticulum.90 These changes arise
asymetrically towards the lumen and lead to segmental
weakening of the artery, predisposing to rupture. Factors
that initiate this arterial change are unknown, although
inflammation does not seem to be a contributing factor.
This finding accords with the clinical impression that
bleeding rarely complicates diverticulitis.
The association of use of non-steroidal antiinflammatories (NSAIDs) with ulcer disease and upper
gastrointestinal bleeding is well documented, but data
have also implicated these drugs in diverticular bleeding.
In a large prospective series of patients with lower
gastrointestinal bleeding (in whom 50% were diverticular), a bleeding risk with NSAIDs was reported that
was equal to that of duodenal ulcer.94 In the Health
Professionals Follow-up Study,95 regular NSAID use was
associated with raised risk of diverticular bleeding.
Whether patients with diverticulosis should be counselled
to avoid NSAIDs—as is done for ulcer patients—or use
COX2 selective agents—is still conjecture.
Clinical features
Clinical presentation of diverticular haemorrhage is
usually one of an abrupt painless onset. The patient can
have mild lower abdominal cramps or the urge to
defecate, followed by passage of voluminous red or
maroon blood or clots. While melaena can sometimes
happen with a slowly bleeding right colon lesion, the
arterial nature of diverticular bleeding makes this
presentation uncommon. Presence of colonic diverticula
should not be judged an adequate explanation for a
positive faecal occult blood test or as a cause of iron
deficiency anaemia. Haemorrhage ceases spontaneously in
70–80% of patients, and rebleeding rates range from 22%
to 38%.88,89,92 The chance of a third bleeding episode can
be as high as 50%, leading many doctors to recommend
surgical resection after a second bleeding episode, similar
to recommendations made for recurrent divericulitis.54,88
Diagnosis and management
Overall management of lower gastrointestinal bleeding is
beyond the scope of this review, but is described in other
636
articles.89,96 Fluid and blood product resuscitation needs
immediate attention. Exclusion of an upper gastrointestinal source by endoscopy is warranted, because
10–15% of patients with haematochezia will have an
upper gastrointestinal tract cause. Flexible sigmoidoscopy
is an appropriate initial approach to rule out an obvious
rectosigmoid lesion, and can be done either unprepared or
after enema administration. If no cause is identified,
further
assessment
with
non-invasive
(nuclear
scintigraphy) or invasive (angiography, colonoscopy)
techniques can be undertaken in an attempt to localise
and treat the bleeding source.
Scintigraphy has several theoretical advantages in
assessment of lower gastrointestinal bleeding. It is noninvasive and sensitive to bleeding rates as low as
0·1 mL/min. Furthermore, once labelled, red cells remain
active for up to 24 h, permitting repeat imaging in the
patient with intermittent bleeding.97 At best, however,
nuclear scans provide information only about the
anatomic site of bleeding, not its cause, and have no
therapeutic potential. Further, accuracy of predicting the
bleeding site has been questioned.98 In view of the high
sensitivity and relative simplicity of scintigraphy, however,
many centres use this method as a screening test before
angiography, to keep the number of negative angiograms
to a minimum and allow for selection of a specific artery
for injection.97
Angiography has a sensitivity for lower gastrointestinal
bleeding at a rate of 0·5 mL/min, although this value is
from animal work.83 An important use of diagnostic
angiography is to identify the site of bleeding with enough
accuracy to allow selective hemicolectomy, rather than
empirical subtotal colectomy, although accuracy has been
questioned.99 An additional role for angiography rests in
its therapeutic potential. Intra-arterial vasopressin can
control haemorrhage in more than 90% of patients.100
This treatment is usually only temporary, however,
because up to half of treated people will rebleed with
discontinuation of infusion. Nonetheless, even temporary
control of bleeding can allow semielective surgical
procedure in a well-prepared patient, rather than
emergency resection, with concomitant reduction in
surgical morbidity.100 Angiographic embolisation of very
distal bleeding branches (subselective) is also effective and
safe.101
For most patients, diverticular bleeding is self-limited.
Subsequent colonoscopy should be done to elucidate the
bleeding source and to exclude neoplasia.9,102–104 The role
of colonoscopy during episodes of lower gastrointestinal
bleeding is being defined.105,106 A rapid oral purge with
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SEMINAR
electrolyte solution to prepare the colon for emergent
colonoscopy has been shown to be safe and effective.107–109
In small series, endoscopy has been used to control acute
bleeding (figure 4).110–118 In a cohort of 48 patients with
lower gastrointestinal bleeding,118 ten had definite signs of
diverticular haemorrhage and were treated endoscopically, and none had recurrent bleeding. In a historical
control group of 17 patients not treated with
colonoscopy,119 nine had additional bleeding. Although
such treatment may be applicable to only a few patients
with lower intestinal bleeding, colonoscopic haemostasis
will probably have an increasing role in the future.
Surgery in lower gastrointestinal bleeding is usually
reserved until endoscopic or angiographic treatments fail.
Segmental resection is most usually done if the bleeding
site is clearly identified from a therapeutically unsuccessful angiographic or endoscopic procedure. Rebleeding
is seen in about 6% of patients.100 In people with persistent
bleeding and no angiographic or endoscopic identification
of a definite bleeding site, subtotal colectomy could be
needed.
Conflict of interest statement
None declared.
Acknowledgments
No funding was received for this Seminar.
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