Diverticular disease of the colon - Perelman School of ...

SEMINAR

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 attributed mainly to dietary changes.5 Results of series of
countries and prevalence rises with age. Although up to two- symptomatic diverticular disease in Africa have shown a
thirds of people older than age 80 years are affected, most rising incidence in increasingly urbanised communities.6,7
remain asymptomatic. The causes of colonic diverticula Cases of complicated diverticulitis have risen 50% in
include alterations in colonic wall resistance, disordered Finland in the past two decades, an increase attributed to an
colonic motility, and dietary deficiencies, especially fibre. ageing population and reduced fibre consumption.8
Clinical manifestations of this disorder range from non- Although much of the epidemiological research mentioned
specific intermittent abdominal pain to potentially life- is simply descriptive, understanding and assessing these
threatening complications such as diverticulitis or noted trends could yield insight into pathogenesis of the
haemorrhage. CT scanning and colonoscopy are important disorder and help to predict disease course and
in diagnosis and management. Here, we review complications.
epidemiology, causes, clinical presentation, and manage-
ment of diverticular disease of the colon. Pathological anatomy
Colonic diverticula typically form in parallel rows between
Epidemiology the taeniae coli because of weakness of the muscle wall at
Prevalence of colonic diverticulosis is difficult to measure sites of penetration of the vasa recta supplying the mucosa.
because most patients are asymptomatic. In early In European and US populations, diverticula arise mainly in
(1920–1940) autopsy and barium enema series, rates of the distal colon, with 90% of patients having sigmoid colon
2–10% were reported.1 Data show a substantial rise in involvement and only 15% having right-sided
colonic diverticula within the past few decades. Prevalence diverticula.3,9–11 This finding is in contrast to that seen in
of diverticular disease increases with age, from less than 10% Asian populations, in which right-sided involvement is more
in people younger than age 40 years to 50–66% in patients prominent.5,12
older than age 80 years.1–3 No sex differences seem to exist.
Diverticula vary from solitary findings to many hundreds.
Diverticulosis has been labelled a disease of western They are typically 5–10 mm in diameter but can exceed
civilisation because of its striking geographic variability. The 2 cm. An entity of giant colonic diverticula has been
disorder is rare in rural Africa and Asia, with the highest described with sizes up to 25 cm. Most are single, located in
prevalence seen in the USA, Europe, and Australia.1 Within the sigmoid colon, and asymptomatic, but can present with
a given country, the incidence of colonic diverticula can vary infection, obstruction, or perforation.13
in ethnic groups—eg, in Chinese inhabitants of Singapore,
incidence was reported to be 0·14 cases per million Search strategy and selection criteria
population per year versus 5·41 cases in Europeans.4
Urbanisation within a country over time can also lead to a Sources of information included: authors’ published work and
rise in prevalence of diverticulosis. Follow-up in Singapore research; and original research, reviews, and practice
has indicated colonic diverticulosis in 19%, an increase guidelines identified by computer database search—eg,
MEDLINE, LexisNexis, The Cochrane Library, and Science
Lancet 2004; 363: 631–39 Citation Index. Most recent publications were prioritised.
Search terms included: “diverticulosis”, “diverticulitis”,
See Personal account page 640 “diverticular disease”, “diverticular hemorrhage”,
“gastrointestinal bleeding”, “diverticular abscess”,
Division of Gastroenterology, San Francisco General Hospital, and “diverticular fistula”, “colonoscopy”, “endoscopy”,
University of California San Francisco, San Francisco, CA, USA “epidemiology”, “pathogenesis”, “motility”, “fiber”,
(N Stollman MD); and Division of Gastroenterology, University of “computerized tomography”, “CT-scanning”, “surgery”,
Miami School of Medicine, Jackson Memorial Medical Center, “laparoscopic”, “ultrasound”, “ultrasonography”, “barium
Miami, FL, USA (Prof J B Raskin MD) enema”, “contrast enema”, “NSAID”, and “non-steroidal
anti-inflammatory”, with Boolean operators AND and OR.
Correspondence to: Dr Neil Stollman, Division of Gastroenterology, Human and animal studies in the English language were
San Francisco General Hospital, 1001 Potrero Avenue, Suite 3-D, reviewed and manually crossreferenced.
San Francisco, CA 94110, USA
(e-mail: [email protected])

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SEMINAR Mesentery series of discrete “little bladders” (figure 1). He proposed
Artery Diverticulum that this segmentation had a physiological role in
delaying of transport and augmentation of water
Contraction Contraction reabsorption but could also generate excessively high
pressures within every bladder, favouring herniation.
Pressure This effect might be amplified by dietary fibre
tracing deficiency.25 Subsequently, patients with symptomatic
diverticulosis have been shown to have higher motility
Figure 1: Segmentation of colon by contractions producing indices than either asymptomatic patients or healthy
little bladders controls.26 High right-sided pressures have also been
Modified from reference 24 with permission of the Royal College of recorded in patients with right-colon diverticulosis,
Surgeons of England, 1964. suggesting that abnormal motility could also have a role
in pathogenesis of proximal diverticula.27 A
Although diverticulosis is an acquired disorder, findings preponderance of excitatory cholinergic nerves and a
of observational studies suggest that the disease pattern— diminution of action of non-adrenergic, non-cholinergic
eg, right-sided, pancolonic—might be established early on inhibitory nerves by nitric oxide have been noted in
and then remain constant, rather than increasing over time diverticular colons compared with controls.28 These
in number and extent. In sequential studies with barium findings suggest that an imbalance in usual excitatory and
enema, no progression of disease has generally been noted inhibitory influences could favour enhanced tonicity.
in most patients.14 In fact, two distinct forms of Whether altered motility and intraluminal hypertension
diverticulosis might exist: one discernible by muscle are a cause of disease or symptoms, or an effect of same,
thickening, mainly in the left colon, and associated with is uncertain.
perforation and diverticulitis; the other due to a diffuse
connective tissue abnormality, resulting in pancolonic Dietary fibre
diverticulosis and a propensity for bleeding.15 This The geographic variability of diverticular disease and
possibility could, in part, account for anatomic differences correlation with a western diet have long suggested a
described between European and US patients and those dietary factor as fundamental in pathogenesis of the
from Asia. disorder. Burkitt and Painter1 were the most eloquent
proponents of this theory, labelling diverticulosis a
Cause and pathogenesis deficiency disease that, like scurvy, could be avoided
Colonic wall resistance with dietary changes. They recorded transit times and
Early gross descriptions of diverticular colons typically stool weights from more than 1200 individuals in the
noted thickening of muscle wall and shortening of the UK and rural Uganda.29 The UK patients, eating a low
taeniae coli, with resultant concertina-like bunching of fibre diet, had transit times of about 80 h and mean stool
haustral folds. Although muscle contraction is noted, weights of 110 g/day. By contrast, rural Ugandans,
routine histology has not generally indicated muscle eating very high fibre diets, had times of 34 h and
hypertrophy. Findings of electron microscopic studies have weights of more than 450 g/day. The longer transit time
shown that diverticular colonic walls consist of structurally and smaller stool volumes were thought to increase
normal muscle cells but elastin deposition is amplified by intraluminal pressure, predisposing to diverticular
more than 200% in muscle cells in the taenia coli compared herniation. As reasonable as this hypothesis seems,
with those without diverticula.16 Elastin is laid down in a results of studies in western populations comparing
contracted form, resulting in shortening of the taenia coli transit times and stool volumes in patients with and
and bunching of circular muscle. Age-related changes in without diverticular disease have failed to show
collagen composition could have a causal role in weakening significant differences. Nonetheless, corroborative data
of wall resistance. An increase in type III collagen synthesis in animals do exist, most notably in rats fed diets of
has been described.17,18 Further, changes in collagen various fibre content throughout their lifespan.30 45% of
crosslinking have been shown in animal and human rats on the lowest fibre diet developed diverticula
models.19,20 The importance of gut wall connective tissue is compared with only 9% of those fed the highest fibre
underscored by early development of diverticula in patients diet. Furthermore, in another animal model, high fibre
with connective tissue disorders such as Marfan’s and diets protected against collagen crosslinking and were
Ehlers-Danlos syndromes.21 associated with reduced frequency of diverticulosis.19

Disordered motility Uncomplicated diverticulosis
In the 1960s, Arfwidsson22 did manometry on patients with Most patients, perhaps 75–80%, with anatomical
or without sigmoid diverticula and showed higher resting, diverticulosis will remain asymptomatic throughout their
postprandial, and neostigmine-stimulated luminal pressures lifetime. Of the few who develop complications,
in diverticular patients than in controls. Painter and diverticulitis—and its difficulties such as abscesses,
colleagues23,24 confirmed these findings in response to fistulas, or obstruction—is the most usual manifestation,
neostigmine or morphine in individuals with sigmoid followed by diverticular haemorrhage, both of which are
diverticula (intraluminal hypertension) and did addressed below.
simultaneous cineradiography. Painter suggested a theory of
segmentation in which contraction of the colon causes a 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 SEMINAR
followed up for more than 4 years, 385 new cases of
symptomatic diverticular disease were identified.31 A Complicated diverticular disease
significant inverse association was recorded between Diverticulitis
dietary fibre intake and risk of development of clinically Diverticulitis is the most usual clinical complication of
evident diverticular disease. Insoluble fibre from fruits diverticular disease, affecting 10–25% of patients with
and vegetables was noted to be more protective than diverticula.3 The process by which diverticulitis arises has
cereal fibres.32 These results provide support for a recom- been likened to that of appendicitis, with a diverticulum
mendation that patients with asymptomatic diverticular becoming obstructed by inspissated stool in its neck.40
disease might benefit from increasing their fruit and This faecalith abrades the mucosa of the sac, causing
vegetable fibre intake, a stance endorsed by the American inflammation and expansion of usual bacterial flora, with
Dietetic Association.33 diminished venous outflow and localised ischaemia.
Bacteria may breach the mucosa and extend the process
The symptomatic patient through the full wall thickness, ultimately leading to
Patients can present with non-specific abdominal perforation.41 Extent and localisation of the perforation
complaints—eg, lower abdominal pain, usually left- will establish its clinical behaviour. Microperforations can
sided—and subsequently be shown to have diverticulosis remain contained by pericolic fat and mesentery and cause
coli; a causal relation is sometimes difficult to establish. small pericolic abscesses. Large perforations can result in
Such patients do not usually manifest signs of inflam- an extensive abscess, which could continue around the
mation, such as pyrexia or neutrophilia, which could bowel wall and form a large inflammatory mass or extend
indicate diverticulitis. Pain is generally exacerbated by to other organs. Free perforation into the peritoneum
eating and diminished with defecation or flatus, which causing frank peritonitis can be life-threatening but is rare.
suggests colonic wall tension due to raised intraluminal
pressure. Patients might also report other symptoms such Clinical features
as bloating or constipation. Assessment can indicate People with diverticulitis generally present with left lower
fullness or mild tenderness in the left lower quadrant, quadrant pain, indicating the propensity for this disorder
but frank rebound or guarding should be absent. to arise in the sigmoid colon in western countries,
A guaiac-positive stool in this setting should never be although individuals with redundant sigmoid colons can
attributed to diverticulosis without complete colonic manifest suprapubic or right-sided pain. Asian patients
assessment. Findings of laboratory studies should be have predominantly right-sided diverticula and will usually
normal. present with right lower quadrant pain.42 Pain may be
intermittent or constant and is sometimes associated with
Diagnostic modalities a change in bowel habits.43 Haematochezia is rare,
For years, barium enema was the standard investigation although anorexia, nausea, and vomiting can arise.
in diverticulosis patients, and although it provides Physical examination usually discloses localised tenderness
information on number and location of colonic and, occasionally, a palpable mass. Bowel sounds are
diverticula, it cannot discern clinical relevance. However, typically depressed but can be normal in mild cases or
inaccurate findings have been reported in nearly a third enhanced in the presence of obstruction. Rectal
of patients with diverticulosis.34 This disorder has, in the examination may reveal tenderness or a mass, especially
past, been regarded as a contraindication to colonoscopy with a low-lying pelvic abscess. Fever is present in most
for fear of causing a perforation.35,36 Further data and patients, although hypotension and shock are unusual.
extensive clinical experience, however, have shown that White blood cell count is sometimes raised.43
colonoscopy is safe in this population, although the
diverticular colon can be difficult to examine because of The differential diagnosis of this presentation includes
spasm, luminal narrowing, and fixation.37 acute appendicitis, especially in Asian patients or those
with redundant sigmoid colons.42 Aphthous ulcers,
Treatment anorectal involvement, and chronic diarrhoea suggest a
Brodribb38 did a randomised double-blind trial of a high- possible diagnosis of Crohn’s colitis. Colon carcinoma,
fibre diet in 18 patients with symptomatic diverticular like diverticulosis, affects colons of ageing westerners, and
disease. A significant placebo effect was noted at a causal relation has been postulated. Most probably,
1 month; however, by 3 months, a significant reduction colon cancer and diverticulosis are both results of the same
in bowel symptoms was seen in patients on the high-fibre environmental effects, mainly dietary. Chronic symptoms
diet. These findings suggest that patients should of weight loss or bleeding should raise suspicion for
gradually increase their dietary fibre over weeks, and be carcinoma. Surgical investigation and resection could be
aware that their symptoms might initially worsen before necessary to make a precise diagnosis. In uncomplicated
they improve, which could take months. In a subsequent cases, elective colonoscopy after acute inflammation has
study,39 no improvement in symptom endpoints was resolved will allow for exclusion of malignant disease.
reported despite a decline in transit times and increases Elderly people with diverticulosis are also at risk for
in stool weight and frequency. Despite these conflicting ischaemic colitis. Features helpful to differentiate between
data, some amelioration of symptoms in patients with these disorders include presence of thumbprinting on
uncomplicated disease can be reasonably expected with a abdominal radiographs and haematochezia, both
high-fibre diet. suggesting ischaemia. Gynaecological disorders, such as
ruptured ovarian cysts, ovarian torsion, ectopic pregnancy,
Hypermotility of the diverticular colon suggests that or pelvic inflammatory disease, can resemble acute
anticholinergic or antispasmodic drugs might improve diverticulitis in female patients. Pelvic ultrasound can be
symptoms by diminishing muscular contraction. helpful in obtaining an accurate diagnosis. Other forms of
Nonetheless, no adequately controlled therapeutic trials colitis, such as pseudomembranous or amoebic, can also
have shown a benefit. No rationale exists for use of mimic diverticulitis.
antibiotics or narcotic analgesics in uncomplicated
diverticular disease. 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 of diverticulitis include pericolic infiltration of fatty tissue,
examination and basic laboratory studies, such as white colonic wall thickening, and abscess formation (figure 3).
blood cell count, should be done in patients coming to In many trials comparing CT with barium enema in
clinical attention. Further studies should be reserved for suspected diverticulitis, sensitivities for CT of 93–98%
individuals in whom diagnosis remains uncertain, and specificities of 75–100% have been consistently
response to empiric treatment is suboptimal, or a reported, significantly more accurate than contrast
complication is suspected. enemas.46,49–51

Chest and abdominal radiographs should generally be Because of risk of perforation from either the device or
done in patients with clinically significant abdominal pain. air insufflation, endoscopy is generally avoided in initial
A chest radiograph taken while the patient is upright can assessment of the patient with acute diverticulitis. Its
aid detection of pneumoperitoneum and help to assess use should be restricted to situations in which diagnosis
cardiopulmonary status. Abdominal radiographs can show of diverticulitis is unclear. In such cases, limited
abnormal findings in 30–50% of patients,44,45 which sigmoidoscopy with minimum insufflation can be helpful
include small or large bowel dilation or ileus, to exclude other diagnoses, such as inflammatory,
pneumoperitoneum, bowel obstruction, or soft-tissue infectious, or ischaemic colitis.
densities suggesting abscesses.
Treatment
Contrast enemas—once the diagnostic standard—are Need for admission is the initial decision to be made in
limited by the fact that diverticulitis is mainly an uncomplicated diverticulitis, which is based on patient’s
extraluminal process. If they are to be undertaken, water- presentation, their ability to tolerate oral intake, severity
soluble contrast material should be used and a low- of illness, comorbid disease, and adequate outpatient
pressure single-contrast study done. Findings deemed support. Outpatients should be treated with a clear liquid
highly suggestive of diverticulitis include extravasated diet and a broad-spectrum oral antibiotic with activity
contrast material outlining an abscess cavity, intramural against anaerobes and gram-negative rods (in particular,
sinus tract, or fistula (figure 2).9,46 Absence of any Escherichia coli and Bacteroides fragilis).52 Symptomatic
diverticula should provoke reconsideration of the improvement should generally be evident within 2–3 days,
diagnosis. In retrospective analyses, contrast enema has at which time diet can be slowly advanced. Antibiotic
been shown to have a sensitivity of 62–94%, with false- treatment should be continued for 7–10 days. Patients
negative results in 2–15%.47,48 needing admission should have clear liquids or nothing by
mouth and intravenous fluids. Intravenous antibiotics
CT scanning has an increasing role in diagnosis, should be started, aimed mainly at colonic anaerobic and
and should be regarded as the diagnostic procedure of gram-negative flora.52 Improvement of symptoms should
choice. Abdominal and pelvic scanning is done with
intravenous, oral, and rectal contrast. Criteria suggestive

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 is indicated. Surgery was previously the main option, but
advanced. If improvement continues, patients may be CT-guided percutaneous drainage of abdominal abscesses
discharged to complete a 7–10 day oral antibiotic course. is now used in preference when feasible. The advantage of
Failure of conservative medical treatment warrants a percutaneous catheter drainage is rapid control of sepsis
diligent search for complications, consideration of and patient stabilisation. Further, drainage might eliminate
alternative diagnoses, and surgical consultation. Most need for a two-stage procedure with interval colostomy,
patients admitted with acute diverticulitis will respond to instead allowing temporary palliative drainage and
conservative treatment, but 15–30% will need surgery subsequent single-stage resection.73,74
during that time.9,48,53 Free perforation with generalised
peritonitis, although uncommon, carries a high mortality Fistulas
rate (up to 35%) and needs urgent surgical intervention.9,48 When a diverticular phlegmon or abscess extends or
ruptures into an adjacent organ, fistulas can arise, the most
For most patients who respond well to conservative typical being colovesicular.75 Such fistulas have a two to one
treatment, an important clinical question subsequently male predominance, attributable to protection of the
revolves around likelihood of recurrence and role of bladder by the uterus and 50% rate of hysterectomy in
prophylactic surgical resection. Risk of recurrent female patients with colovesical fistulas. Pneumaturia and
symptoms after an attack of acute diverticulitis has been faecaluria are suggestive signs.76 Cystoscopy, cystography,
reported between 7% and 45%; a third is a reasonable and contrast radiographs or methylene blue studies can
approximation.9,48,53 Recurrent attacks are less likely to show fistula tracts. Single-stage operative resection with
respond to medical treatment and have a high mortality fistula closure can be undertaken in most patients.75,76
rate;48,53 thus, most authorities agree that elective resection Colovaginal fistulas are the next most frequent,
is indicated after two attacks of uncomplicated representing about 25% of all cases.75 Passage of stool or
diverticulitis.54–56 The risk-benefit analysis of such an flatus via the vagina is pathognomonic. Frequent vaginal
approach must be tailored with consideration of severity infections or copious discharge should prompt consid-
and responsiveness of the episode, general health of the eration of a colovaginal fistula. Treatment is surgical
patient, and risk of subsequent occurrence. Risk of resection of the diseased colon with repair of the contiguous
resection is an evolving factor, with reports of increasingly organ.56 Coloenteric, colouterine, coloureteral, and
favourable experiences with laparoscopic resections for colocutaneous fistulas arise much less typically.
diverticular disease.57–62 This approach might reduce the
threshold for resection in some patients by lowering Obstruction
operative morbidity. However, some patients will still have During an episode of acute diverticulitis, partial colonic
symptoms after surgical resection. obstruction can happen because of relative lumenal
narrowing from pericolic inflammation or compression
Diverticulitis in special situations from abscess formation. Colonic pseudo-obstruction can
Diverticulitis is seen in about 2–5% of people younger also take place. Acute diverticulitis might cause small bowel
than 40 years old,9,53 mainly in males.9,63,64 Disease is more obstruction or ileus if a loop of small intestine becomes
virulent in young patients, with 66–88% needing urgent incorporated into the inflammatory mass. These
surgery during their initial attack, with a high risk of presentations usually improve as inflammation subsides
recurrences or complications.9,63,65,66 Obesity can also be an with effective treatment; failure to do so should prompt
important risk factor in young people.67 For these reasons, surgical consultation.
and because of the low operative risk of an elective
procedure in an otherwise healthy young patient, resection Recurrent episodes of diverticulitis, sometimes sub-
is generally indicated after one well-documented episode clinical, can initiate progressive fibrosis and stricturing of
of uncomplicated diverticulitis.48,54 Others, however, have the colonic wall without persisting inflammation.
questioned this assertion.56,68,69 Ultimately, high-grade or complete obstruction can
happen, needing surgery. An insidious presentation with
Immunocompromised patients with diverticulitis may non-specific symptoms is typical. Generally, a stricture with
present with more subtle signs and symptoms than those uncertain cause is identified on barium enema. The
who are immunocompetent and represent a difficult important issue is to distinguish between a diverticular
diagnostic challenge. They are less likely to benefit from stricture and a stenosing neoplasm. Doctors should attempt
medical treatment and have a higher rate of free to make this differentiation by colonoscopy with biopsy, but
perforation, need for surgery, and postoperative mortality this procedure is not always possible.77 Strictures in which
than non-compromised patients.70,71 Because of this high malignant disease cannot be excluded should undergo
risk, some authorities have advocated elective resection surgical en bloc resection. A trial of endoscopic treatment
after one episode in an immunosuppressed individual.54 with balloon dilation can be attempted in patients in whom
neoplasm is judged sufficiently excluded.78–80 Early work
Complicated diverticulitis with colonic metal stents has suggested that they might
Abscess have a role in colonic obstruction due to diverticular
When perforation of a diverticulum takes place, a localised disease. Stenting can provide temporary decompression,
phlegmon initially develops; further spread can lead to allowing for bowel preparation and subsequent single-stage
formation of large local or distant abscesses. Clinical signs resection without diversion.81,82
suggesting abscess formation include a tender mass on
investigation or persistent fever despite an adequate trial Haemorrhage
of antibiotics. When an abscess is suspected, CT scanning Important lower gastrointestinal bleeding can be caused
is the best modality for making the diagnosis and following by diverticula, vascular ectasias, colitis, or neoplasms.10,83–85
its course. Diverticular sources have been reported to be the most
typically identified cause, accounting for greater than 40%
Small pericolic abscesses can generally be treated of lower gastrointestinal bleeding episodes.86,87 Severe
conservatively with continued antibiotics and bowel haemorrhage can arise in 3–5% of patients with
rest.56,72 In patients in whom surgery is needed, a single- diverticulosis.10,88,89 Despite the fact that most diverticula
stage resection and anastomosis can generally be done.
For those with distant or unresolving abscesses, drainage

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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 articles.89,96 Fluid and blood product resuscitation needs
bleeding may more often be located in the proximal immediate attention. Exclusion of an upper gastro-
colon.10,88,90–93 intestinal source by endoscopy is warranted, because
10–15% of patients with haematochezia will have an
Pathophysiology upper gastrointestinal tract cause. Flexible sigmoidoscopy
Microangiography on resected specimens from patients is an appropriate initial approach to rule out an obvious
with bleeding diverticula shows intimal thickening and rectosigmoid lesion, and can be done either unprepared or
medial thinning of the vasa recta as it courses over the after enema administration. If no cause is identified,
dome of the diverticulum.90 These changes arise further assessment with non-invasive (nuclear
asymetrically towards the lumen and lead to segmental scintigraphy) or invasive (angiography, colonoscopy)
weakening of the artery, predisposing to rupture. Factors techniques can be undertaken in an attempt to localise
that initiate this arterial change are unknown, although and treat the bleeding source.
inflammation does not seem to be a contributing factor.
This finding accords with the clinical impression that Scintigraphy has several theoretical advantages in
bleeding rarely complicates diverticulitis. assessment of lower gastrointestinal bleeding. It is non-
invasive and sensitive to bleeding rates as low as
The association of use of non-steroidal anti- 0·1 mL/min. Furthermore, once labelled, red cells remain
inflammatories (NSAIDs) with ulcer disease and upper active for up to 24 h, permitting repeat imaging in the
gastrointestinal bleeding is well documented, but data patient with intermittent bleeding.97 At best, however,
have also implicated these drugs in diverticular bleeding. nuclear scans provide information only about the
In a large prospective series of patients with lower anatomic site of bleeding, not its cause, and have no
gastrointestinal bleeding (in whom 50% were diver- therapeutic potential. Further, accuracy of predicting the
ticular), a bleeding risk with NSAIDs was reported that bleeding site has been questioned.98 In view of the high
was equal to that of duodenal ulcer.94 In the Health sensitivity and relative simplicity of scintigraphy, however,
Professionals Follow-up Study,95 regular NSAID use was many centres use this method as a screening test before
associated with raised risk of diverticular bleeding. angiography, to keep the number of negative angiograms
Whether patients with diverticulosis should be counselled to a minimum and allow for selection of a specific artery
to avoid NSAIDs—as is done for ulcer patients—or use for injection.97
COX2 selective agents—is still conjecture.
Angiography has a sensitivity for lower gastrointestinal
Clinical features bleeding at a rate of 0·5 mL/min, although this value is
Clinical presentation of diverticular haemorrhage is from animal work.83 An important use of diagnostic
usually one of an abrupt painless onset. The patient can angiography is to identify the site of bleeding with enough
have mild lower abdominal cramps or the urge to accuracy to allow selective hemicolectomy, rather than
defecate, followed by passage of voluminous red or empirical subtotal colectomy, although accuracy has been
maroon blood or clots. While melaena can sometimes questioned.99 An additional role for angiography rests in
happen with a slowly bleeding right colon lesion, the its therapeutic potential. Intra-arterial vasopressin can
arterial nature of diverticular bleeding makes this control haemorrhage in more than 90% of patients.100
presentation uncommon. Presence of colonic diverticula This treatment is usually only temporary, however,
should not be judged an adequate explanation for a because up to half of treated people will rebleed with
positive faecal occult blood test or as a cause of iron discontinuation of infusion. Nonetheless, even temporary
deficiency anaemia. Haemorrhage ceases spontaneously in control of bleeding can allow semielective surgical
70–80% of patients, and rebleeding rates range from 22% procedure in a well-prepared patient, rather than
to 38%.88,89,92 The chance of a third bleeding episode can emergency resection, with concomitant reduction in
be as high as 50%, leading many doctors to recommend surgical morbidity.100 Angiographic embolisation of very
surgical resection after a second bleeding episode, similar distal bleeding branches (subselective) is also effective and
to recommendations made for recurrent divericulitis.54,88 safe.101

Diagnosis and management For most patients, diverticular bleeding is self-limited.
Overall management of lower gastrointestinal bleeding is Subsequent colonoscopy should be done to elucidate the
beyond the scope of this review, but is described in other 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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electrolyte solution to prepare the colon for emergent 20 Wess L, Eastwood MA, Wess TJ, Busuttil A, Miller A. Cross linking
colonoscopy has been shown to be safe and effective.107–109 of collagen is increased in colonic diverticulosis. Gut 1995; 37: 91–94.
In small series, endoscopy has been used to control acute
bleeding (figure 4).110–118 In a cohort of 48 patients with 21 Simpson J, Scholefield JH, Spiller RC. Pathogenesis of colonic
lower gastrointestinal bleeding,118 ten had definite signs of diverticula. Br J Surg 2002; 89: 546–54.
diverticular haemorrhage and were treated endoscopi-
cally, and none had recurrent bleeding. In a historical 22 Arfwidsson S, Kock N, Lehmann L, Winberg T. Pathogenesis of
control group of 17 patients not treated with multiple diverticula of the sigmoid colon in diverticular diseases.
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None declared. Dis Colon Rectum 1991; 34: 339–42.

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