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1. DIVERTICULITIS
By solomon L.(MD,Resident)

2. • Diverticula are small (0.5 to 1.0 cm in diameter) out pouchings of the
colon that occur in rows at sites of vascular penetration between the single
mesenteric taenia and one of the antimesenteric taeniae
• At the sites of most diverticula, the muscular layer is absent [Figure 1].
• Technically, such lesions are really pseudodiverticula; true diverticula
(which are much less common than pseudodiverticula) involve all layers
of the bowel wall
• Nevertheless, both pseudodiverticula and true diverticula are generally
referred to as diverticula

3. • The sigmoid colon is the most common site of diverticula:
• in 90% of patients with diverticulosis, the sigmoid colon is involved.
• If a diverticulum becomes inflamed as a result of obstruction by feces or
hardened mucus or of mucosal erosion, a localized perforation
(microperforation) may occur—a process known as diverticulitis
• The incidence of diverticulitis has been estimated to be about 10 to 25%
in patients with colonic diverticula
• Limited prospective data suggest that the risk of developing diverticulitis
is low in patients with symptomatic diverticulosis
• Both diverticulosis and variants of diverticulitis may be subsumed under
the more encompassing term diverticular disease.

4. • The incidence of diverticular disease increases with age.
• Diverticula are quite common in elderly patients, bein present in more than
80% of patients older than 85 years
• A diet containing refined carbohydrates and low-fiber substances, such as is
currently widespread in many developed countries (especially in the West),
has been associated with the emergence of this disease entity
• A low-residue diet facilitates the development of constipation, which can lead
to increased intraluminal pressure in the large bowel
• In addition, elevated elastin levels are commonly noted at colon wall sites
containing diverticula, and this change causes shortening of the taeniae
• High-pressure zones or areas of segmentation may develop [see Figure 2],
usually in the sigmoid colon, and diverticula begin to protrude at these
locations
• If microperforation of a thin-walled diverticulum takes place, local or,
uncommonly, widespread contamination with fecal organisms may ensue
• The pericolic tissue (typically, the mesentery and the pericolic fat) thus
becomes inflamed, whereas the mucosa tends to remain otherwise normal

6. • Several factors appear to promote the development of diverticular disease
and its complications, including
– decrease physical activity, obesity, intake of nonsteroidal antiinflammatory drugs
(NSAIDs), smoking, and constipation from any cause (e.g., diet or medications).
• The well-known Western afflictions cholelithiasis, diverticulosis, and
hiatal hernia frequently occur together (the Saint triad)
• Obesity has been associated with the intake of low-fiber diets, and
growing
numbers of young, obese patients with diverticulitis are being seen by
physicians
• Consumption of nuts, corn, or popcorn does not increase the incidence of
diverticulitis or diverticular bleeding

7. • Clinical Evaluation
history
Uncomplicated (Simple) Diverticulitis
• The classic symptoms of uncomplicated acute diverticulitis are left lower quadrant
abdominal pain, a low-grade fever, irregular bowel habits, and, possibly, urinary
symptoms if the affected colon is adjacent to the bladder
• If the sigmoid colon is highly redundant, pain may be greatest in the right lower
quadrant
• Diarrhea or constipation may occur, together with rectal urgency
• The differential diagnosis includes gynecologic and urinary disorders, perforated colon
carcinoma, Crohn disease, ischemic colitis, and, sometimes, appendicitis.
• Chronic diarrhea, multiple areas of colon involvement, perianal disease, perineal or
cutaneous fistulas, or extraintestinal signs are suggestive of Crohn disease
• Rectal bleeding should raise the possibility of inflammatory bowel disease, ischemia,
or carcinoma; such bleeding is uncommon with diverticulitis alone
• Given the prevalence of diverticula, it is not surprising that colon carcinoma may
coexist with diverticular disease [see Figure 3].

8. • Complicated Diverticulitis
• Some cases of diverticulitis are classified as complicated, meaning that the disease
process has progressed to obstruction, abscess or fistula formation, or free perforation
[see Figure 4].
• Complicated diverticulitis may be particularly challenging to manage especially
because patients may have no known history of diverticular disease
• Lower gastrointestinal (GI) bleeding is also a complication of diverticular disease in 30
to 50% of cases
• in fact, diverticula are the most common colonic cause of lower GI bleeding
• When diverticular hemorrhage occurs it is usually associated with diverticulosis rather
than with diverticulitis
• Approximately 50% of diverticular bleeding originates in the right colon, despite the
low incidence of diverticula in this segment of the colon.
• Patients tend to be elderly and to have cardiovascular disease and hypertension
• Regular intake of NSAIDs may increase the risk of this complication.
• Although patients may lose 1 to 2 units of blood, the bleeding usually ceases
spontaneously and expeditious operative treatment generally is not necessary

9. • The most common form of complicated diverticulitis involves the
development of a pericolic abscess, typically signaled by high fever, chills,
and lassitude
• Such abscesses may be small and localized or may extend to more distant
sites (e.g., the pelvis).
• They may be categorized according to the Hinchey classification of
diverticular perforations, in which stage I refers to a localized pericolic
abscess and stage II to a larger mesenteric abscess spreading toward the
pelvis [see Figure 5].
• On rare occasions, an abscess forms in the retroperitoneal tissues,
subsequently extending to distant sites such as the thigh or the flank
• The location of the abscess can be defined precisely by means of
computed tomography (CT) with contras

10. • Some abscesses rupture into adjacent tissues or viscera, resulting in the
formation of fistulas
• The fistulas most commonly seen in this setting (50 to 65% of cases) are
colovesical fistulas
• This complication is less common in women because of the protection
afforded by the uterus
• Symptoms of colovesical fistulas tend to involve the urinary tract (e.g.,
pneumaturia, hematuria, and urinary frequency)
• Fecaluria is diagnostic of colovesical or enterovesical fistulas
• Colovaginal fistulas (which account for 25% of all diverticular fistulas) are
usually seen in women who have undergone hysterectomies
• The diseased colon is adherent to the vaginal cuff
• Most commonly, patients complain of a foul vaginal discharge; however,
some patients present with stool emanating from the vagina

11. • About 10% of colon obstructions are attributable to diverticulitis
• Acute diverticulitis can cause colonic edema and a functional obstruction
that usually resolves with antibiotic infusion and bowel rest
• Stricture formation is more common, usually occurring as a consequence
of recurrent attacks of diverticulitis
• Circumferential pericolic fibrosis is noted, and marked angulation of the
pelvic colon with adherence to the pelvic sidewall may be seen
• Patients complain of constipation and narrowed stools
• Colonoscopy can be difficult and potentially dangerous in this setting
• Differentiating a diverticular stricture from carcinoma may be impossible
by any means short of resection
• The term malignant diverticulitis has been employed to describe an
extreme form of sigmoid diverticulitis that is characterized by an
extensive phlegmon and inflammatory reaction extending below the
peritoneal reflection, with a
tendency toward obstruction and fistula formation

12. • Malignant diverticulitis is seen in fewer than 5% of patients older than 50
years who are operated on for diverticulitis
• The process is reminiscent of Crohn disease, and CT scans demonstrate
extensive inflammation
• In this setting, a staged resection might be preferable to attempting a primary
resection through the pelvic phlegmon
• The degree of pelvic inflammation may subside significantly after diversion
• A dangerous but rare complication of acute diverticulitis (occurring in 1 to 2%
of cases) is free perforation,
• which includes both
– perforation of a diverticular abscess throughout the abdomen leading to generalized
peritonitis (purulent peritonitis; Hinchey stage III) and
– free spillage of stool thorough an open diverticulum into the peritoneal cavity (fecal
peritonitis; Hinchey stage IV)
• The overall mortality in this group is between 20 and 30%, that for purulent
peritonitis is approximately 13%, and that for fecal peritonitis is about 43%

13. • physical examination
Complicated Diverticulitis
• In a patient with a pericolic abscess, a mass may be detectable on abdominal,
rectal, or pelvic examination
• In a patient with a colovaginal fistula, a site of granulation tissue and
drainage is seen at the apex of the vaginal cuff
• In a patient with obstruction, there may be marked abdominal distention,
usually of slow onset; abdominal tenderness may or may not be present, but if
tears develop in the cecal taeniae, right lower quadrant tenderness is typically
seen
• In a patient with a free perforation, there is marked abdominal tenderness,
usually commencing suddenly in the left lower quadrant and spreading within
hours to the remainder of the abdomen
• Hypotension and oliguria may develop later
• Patients with rectal bleeding usually have no complaints of abdominal pain
or tenderness, and they may be hypovolemic and hypotensive, depending on
the rapidity of the bleeding

14. • Investigative Studies
• Imaging
• The most useful diagnostic imaging study in the setting of suspected
diverticulitis is a CT scan with oral and rectal contrast
• Localized thickening of the bowel wall or inflammation of the adjacent
pericolic fat is suggestive of diverticulitis
• extraluminal air or fluid collections are sometimes seen together with
diverticula [see Figure 6].
• The most frequent findings (seen in 70 to 100% of cases) are bowel wall
thickening, fat stranding, and diverticula
• In some cases, small abscesses in the mesocolon or bowel wall are not
detected
• The diagnosis of carcinoma cannot be excluded definitively when there is
thickening of the bowel wall ---MRI prefered

15. • Although CT has tended to replace contrast studies in the evaluation of
diverticulitis, the latter may be more useful in differentiating carcinoma from
diverticulitis
• A contrast study can also be complementary when the CT scan raises the
suspicion of carcinoma
• When diverticulitis is suspected, water soluble contrast material should be
used instead of barium because of the complications that follow extravasation
of barium [see Figure 8 and Figure 9]
• Furthermore, in the acute setting, only the left colon should be evaluated
• Carcinoma is suggested by an abrupt transition to an abnormal mucosa over a
relatively short segment;
• diverticulitis is usually characterized by a gradual transition into diseased
colon over a longer segment, with the mucosa remaining intact.
• If the contrast study reveals extravasation of contrast outlining an abscess
cavity [see Figure 9], an intramural sinus tract, or a fistula, diverticulitis is
likely.

16. • Colonoscopy is avoided when acute diverticulitis is suspected because of the
risk of perforation.
• It may, however, be done 6 to 8 weeks after the process subsides to rule out
other disorders (e.g., colon cancer) [see Figure 10].
• When a patient does not respond to therapy, gentle flexible sigmoidoscopy
may detect a carcinoma or some other abnormality.
• If diverticular disease is advanced, the endoscopic procedure may be difficult;
the diverticular segment must be fully traversed for the examiner to be able to
exclude a neoplasm with confidence
• When major lower GI bleeding occurs, colonoscopy is done to search for
polyps, carcinoma, or a site of diverticular bleeding.
• In the case of massive bleeding, selective arteriography is useful for localizing
the source, and superselective embolization frequently quells the
hemorrhage.
The actual risk of bowel ischemia is low when superselective techniques are
employed.
• Bleeding at the time of arteriography may be facilitated by the infusion of
heparin or urokinase; however, this is a risky approach that should be taken
only

17. • when other attempts at localization have failed and recurrent
bouts of bleeding have occurred
• When a colovesical fistula occurs, contrast CT with narrow
cuts in the pelvis can be very helpful
• The classic findings are sigmoid diverticula, thickening of the bladder and
the colon, air in the bladder, opacification of the fistula tract and the
bladder, and, possibly, an abscess [see Figure 11].
• Cystoscopy is less specific, showing possible edema or erythema at the
site of the fistula.
• A contrast enema helps rule out malignant disease

18. • The diagnostic tests that are most useful for detecting colovaginal fistulas
are contrast CT and vaginography via a Foley catheter
• Charcoal ingestion helps confirm the presence of colovesical or
colovaginal fistulas
• On rare occasions, colocutaneous fistulas may develop, causing erythema
and breakdown of the skin
• Colouterine fistulas may occur as well; these are also quite rare

19. • Management
medical
• Uncomplicated diverticulitis is usually managed on an outpatient basis by
instituting a liquid or low-residue diet and administering an oral antibiotic
combination that covers anaerobes and gram-negative organisms (e.g.,
ciprofloxacin with metronidazole or clindamycin) over a period of 7 to 10
days
• Provided that symptoms and signs have subsided, the colon may be evaluated
more fully several weeks later with a contrast study or colonoscopy if the
diagnosis of diverticular disease has not already been established
• If symptoms worsen, hospitalization should be considered
• Over the long term, patients should be maintained on a high-fiber diet,
although
it may take months for the diet to have an effect on symptoms
• Limited trials suggest that other substances such as probiotics and
antiinflammatory agents such as mesalazine may help prevent recurrent
attacks

20. • If more significant physical findings and symptoms of toxicity develop,
hospitalization is warranted [see Figure 12]
• Patients are placed on a nihil per os (NPO) regimen, and intravenous
fluids and antibiotics are administered (e.g., a third-generation
cephalosporin with metronidazole) until abdominal pain and
tenderness have resolved and bowel function has returned
• As a rule, resolution occurs within several days
• If there is clinical evidence of intestinal obstruction or ileus, a nasogastric
tube
is placed
• In most cases, ileus-related symptoms resolve with antibiotic treatment
• CT scans are useful for establishing the correct diagnosis in the emergency
department
• furthermore, the severity of diverticulitis on CT scans predicts the risk of
subsequent medical failure

21. • Following the sedimentation rate may be helpful in assessing the effectiveness of
treatment
• Most patients recover with conservative management alone
• By observing early trends in the leukocyte count and the maximum temperature
in patients with acute diverticulitis, one can predict whether they will recover
quickly as expected or if they will likely require prolonged intravenous antibiotics
and/ or an operation
• It has been estimated that 15 to 30% of patients admitted with acute diverticulitis
will require surgical treatment during the same admission
• If fever and leukocytosis persist despite antibiotic therapy, the presence of an
abscess should be suspected
• Small (< 5 cm) abscesses may respond to antibiotic infusion and bowel rest
• Larger abscesses that are localized and isolated may be accessible to percutaneous
drainage [see Figure 13]
• Generally, this technique is reserved for abscesses greater than 5 cm in diameter in
low-risk patients who are not immunocompromised
• It often leads to resolution of sepsis and the resulting symptoms and signs (e.g.,
abdominal pain and tenderness and leukocytosis), usually within 72 hours,
thereby facilitating subsequent elective surgical resection of the colon

22. • If the catheter drainage amounts to more than 500 mL/day after the first
24 hours, a fistula should be suspected
• Before the catheter is removed, a CT scan is done with injection of
contrast material through the tube to determine whether the cavity has
collapsed
• If this approach fails (as it usually does in patients with multiple or
multiloculated abscesses), an expeditious operation may be
necessary
• An initial surgical procedure is required in about 20% of case

23. • surgical
• 20% of patients with diverticulitis require surgical treatment
• Most surgical procedures are reserved for patients who experience recurrent
episodes of acute diverticulitis that necessitate treatment (inpatient or
outpatient) or who have complicated diverticulitis
• The most common indication for elective resection is recurrent attacks—
that is, several episodes of acute diverticulitis documented by
studies such as CT
• Rerecurrences may be more common than recurrences
• the American Society of Colon and Rectal Surgeons recommended sigmoid
resection after two attacks of diverticulitis
• Current practice guidelines state that the recommendation to perform elective
sigmoid resection after recovery from uncomplicated acute diverticulitis
should be made on a case-by-case basis
• The decision-making process should be influenced by the age and medical
condition of the patient, the frequency and severity of attacks, and the
presence of symptoms after the acute attack

24. • Elective resection is generally recommended after an episode of
complicated diverticulitis
• Efforts are made to time surgical treatment so that it takes place during a
quiescent period 8 to 10 weeks after the last attack
• Barium enema or colonoscopy may be employed to evaluate the
diverticular disease and rule out carcinoma
• The bowel can then be prepared mechanically and with antibiotics (e.g.,
oral neomycin and metronidazole on the day before operation
• Elective resection is a common sequel to successful percutaneous drainage
of a pelvic abscess in an otherwise healthy, well-nourished patient
• The timing of surgery may be guided by
• the extent of the inflammatory changes (as documented by CT scanning)
and
• the patient’s clinical course
• Most patients can be operated upon within 6 weeks

25. • Elective resection is the preferred approach to diverticular fistulas as well
• Colovesical fistulas are usually resected because of
• the risk of urinary sepsis and
• the concern that a malignancy might be overlooked
• Elective resection is done via either the open route or, increasingly, the
laparoscopic route
• Minimally invasive procedures have several advantages over conventional
procedures
• decreased intraoperative trauma, fewer postoperative adhesions, reduced
postoperative pain, shorter duration of ileus, quicker discharge from the
hospital, and earlier return to work
• Such procedures can be done safely in obese patients, and the conversion
rate is now low

26. • Some patients with complicated diverticulitis require emergency resection
because of free perforation and widespread peritonitis
• One of the unfortunate limitations of the Hinchey classification is that it
does not take comorbidities into account
• Because the bowel is not prepared before operation, the surgeon may feel
uncomfortable doing an anastomosis
• On-table lavage may be considered if contamination is minimal, but it
adds to the time spent under anesthesia during an emergency procedure
• As a general rule, resection and immediate anastomosis (open or
laparoscopic) are suitable for Hinchey stage I and perhaps stage II
diverticular perforations,
• whereas resection with diversion (the Hartmann procedure) is the gold
standard
for stage III and especially stage IV
• This recommendation is based on the finding that an anastomosis
involving the left colon is risky when performed under emergency
conditions

27. • The once-popular three-stage procedures are now of historical interest
only
• There are some reports of successful outcomes for type III and type IV
cases after extensive abdominal lavage and two-layer anastomoses or
• after on-table lavage of the colonic contents to allow primary anastomosis
• recent reports : laparoscopic peritoneal lavage and intraperitoneal
drainage for the treatment of purulent peritonitis (Hinchey III)
• Morbidity has been low, and a delayed laparoscopic sigmoid resection has
been possible
• Grading of comorbidities with classification systems such as APACHE II or
the Mannheim peritonitis index can facilitate decision making with
respect to the question of anastomosis versus diversion
• The surgeon’s decision must be individualized on the basis of each
patient’s condition and needs

28. • Currently, surgeons encountering acute diverticulitis are more likely to do
one-stage resections, as opposed to Hartmann procedures, than they once
were
• The advantage of the one-stage approach is
– the colostomy takedown,
– frequent postoperative complications, and
– attendant 4% mortality are avoided
• Furthermore, at least 30% of patients who undergo a Hartmann
procedure never return for colostomy closure
• A primary anastomosis can be protected with a proximal ileostomy as well
• Transverse colostomy and loop ileostomy appear to be equally safe,
although skin changes may be more problematic after a colostomy and an
ileostomy closure tends to be less complex than a colostomy closure
• On-table lavage may also be used as an adjunct to anastomosis

29. • Potential complications include
• ureteral injuries;
• anastomotic leakage, anastomotic stricture, and postoperative intra-
abdominal abscesses;
• perioperative bleeding involving the mesentery, adhesions, the splenic
capsule, or the presacral venous plexus;
• postoperative small bowel obstruction;
• stomal complications;
• wound infection, wound dehiscence, and abdominal compartment
syndrome;
• acute respiratory distress syndrome; and
• multiple organ dysfunction syndrome
• Even after successful operations, some patients continue to have
abdominal pain attributable to factors such as irritable bowel syndrome

32. • Large bowel obstruction secondary to diverticulitis can lead to
considerable morbidity and may necessitate surgical intervention
• The obstruction is usually partial [see Figure 14 and Figure 15], allowing
preparation of the bowel in many cases
• High-grade obstruction represents a complex problem
• If the cecum is dilated to a diameter of 10 cm or greater and there is
tenderness in the right lower quadrant, expeditious surgery is necessary
because of the risk of cecal necrosis and perforation
• High-grade obstruction with fecal loading of the colon is usually managed
by performing a Hartmann procedure, although on-table lavage may be
considered
• A survey of GI surgeons in USA indicated that 50% would opt for a one
stage procedure in low-risk patients with obstruction,
• whereas 94% would opt for a staged procedure in high-risk patients

33. • Small bowel obstruction may also complicate the clinical picture
• Mechanical small bowel obstruction may occur as a consequence of
adherence of the small bowel to a focus of diverticulitis, especially in the
presence of a large pericolic abscess
• Whereas small bowel obstruction tends to cause periumbilical crampy
abdominal pain and vomiting, these characteristic manifestations may be
obscured in part by pain attributed to diverticulitis
• The concern in this situation is that ischemic small bowel may be ignored,
with potentially disastrous consequences
• Diarrhea should trigger the suspicion of colonic disease, and formation of
a fistula into the small bowel should raise the possibility of Crohn disease
• CT scanning often helps the surgeon differentiate between primary and
secondary small bowel obstruction, but, ultimately, exploration

34. • surgery may be required for both diagnosis and treatment
• Lower GI bleeding caused by diverticular disease rarely calls for emergency
resection because the bleeding is self limited in most patients (80 to 90%)
• Furthermore, active diverticulitis is rare when active bleeding is the
presenting
symptom
• Attempts are made to establish the active bleeding site by means of
colonoscopy, tagged red blood cell nuclear scans, or angiography; barium
contrast studies have no role to play in this situation.
• Emergency resection is indicated if the bleeding is life-threatening and if
colonic angiography and attempted super selective embolization prove
unsuccessful
• In an unstable patient, total abdominal colectomy is necessary if the site of
bleeding is unknown, although identification of the bleeding site with
intraoperative colonoscopy has been reported
• In a stable patient with ongoing bleeding, repeat angiography at a later time is
appropriate, or so-called pharmacoangiography (infusion of heparin) can be
employed in an attempt to induce bleeding

35. • Special Types of Diverticulitis
• cecal diverticulitis
In the United States, diverticulitis rarely involves the cecum or the right
colon
• Right-side diverticula occur in only 15% of patients in Western countries,
compared with 75% in Singapore
• The incidence of cecal diverticulitis appears to be related to the number of
diverticula present
• A classification system has been proposed that divides cecal diverticulitis
into
four grades [see Figure 16] to facilitate comparisons between
different clinical series and to help surgeons formulate treatment plans in
the operating room
• Some cecal diverticula are true diverticula, containing all layers of the
bowel wall, but the majority are pseudodiverticula. Diverticulitis of the
hepatic flexure and the transverse colon is even less common
and can present with symptoms suggesting appendicitis

36. • Patients with right-side disease tend to be younger and to
have less generalized peritonitis than patients with left-side
diverticulitis.67,68 Because they typically present with right
lower quadrant pain, fever, and leukocytosis, acute appendicitis is usually
suspected. CT scans are helpful for differentiating cecal diverticulitis from
appendicitis or colon cancer [see
Figure 17].69 If cecal diverticulitis is suspected (as in a patient
who has previously undergone appendectomy or in a patient
with known right-side diverticulosis who has experienced
similar attacks in the past), medical management with observation and
antibiotics is generally the favored strategy, just as
with simple sigmoid diverticulitis. In Japan, where right-side
diverticulitis is more common, medical treatment has been
successfully used for recurrent attacks of uncomplicated
right-side diverticulitis.70 After a few weeks, colonoscopy
should be performed to rule out a colonic neoplasm

37. • If the patient has significant peritonitis or the diagnosis is
unclear, laparoscopy or laparotomy is indicated. It is important that one or the other be done
because the mortality associated with delayed treatment of perforated cecal diverticulitis
is high. In our institution, laparoscopy is usually employed; if
the diagnosis is unclear, laparotomy is recommended. When
inflammation is localized and minimal, colectomy is unnecessary, and incidental
appendectomy should be considered if
the cecum is uninvolved at the base of the appendix.71 If
desired, the diverticulum may be removed as well.
Diverticulectomy should be done only if (1) carcinoma
can be ruled out, (2) the resection margins are free of inflammation, (3) the ileocecal valve
and the blood supply of the
bowel are not compromised, and (4) perforation, gangrene,
and abscess are absent.67 Localized diverticulectomy, in general, should be reserved for
grade I and grade II disease.67
Sometimes, the ostium of the inflamed diverticulum is palpable if the cecum is mobilized
surgically. On-table cecoscopy through the appendiceal stump has also been helpful in
establishing the diagnosis in the operating room.71 Grade III
and IV cecal diverticulitis may be difficult to differentiate
from carcinoma; resection is favored for these lesions. An
anastomosis may be created if contamination is limited, but,
generally, primary resection, ileostomy, and a mucous fistula
are favored for treatment of grade IV disease.

38. • diverticulitis in young patients
Diverticulitis in patients younger than 40 years has been a
focus of considerable attention in the literature, although this
group represents only about 2 to 5% of the patients in large
series.32 The incidence of diverticulitis in young patients may
be increasing, and obese Latino men appear to be at particular risk.72 This
predominance in males reflects a tendency to
underdiagnose acute diverticulitis in young women.73 Some
authors have asserted that diverticulitis is particularly virulent
in young patients; however, current data tend not to support
this concept, suggesting that patients with mild diverticulitis
are misdiagnosed when hospitalized or are treated as outpatients. The high
rate of early operation in young patients
probably reflects misdiagnosis of diverticulitis as acute appendicitis rather
than the development of particularly severe
forms of diverticulitis.72 Patients found to have uncomplicated acute
diverticulitis may, if desired, undergo incidental
appendectomy in conjunction with medical treatment of
diverticulitis

39. • Unlike elderly patients, hospitalized young patients with
diverticulitis tend to have few comorbidities other than
obesity. Furthermore, young patients hospitalized for diverticulitis tend to
have relatively advanced disease, perhaps as
a consequence of delayed diagnosis, whereas elderly patients
hospitalized with an admitting diagnosis of diverticulitis tend
to exhibit a wider spectrum of disease severity. Young patients
appear not to have a higher rate of recurrent diverticulitis
than older patients do; thus, aggressive resection is not necessary at the time
of the first attack.72 However, a finding of
advanced diverticulitis on CT scans is a predictor of subsequent disease
complications in this population.74
In general, diverticulitis should be approached in the same
fashion in younger patients as in older patients.74 The
pathophysiology of the disease is probably identical. As in the
elderly, elective resection is recommended after recurrent
attacks, not after a single attack; with follow-up, the majority
of patients hospitalized with acute diverticulitis do not require
operation.

40. • diverticulitis in
immunocompromised patients
In view of their known predisposition to infection, immunocompromised
patients (e.g., chronic alcoholics, transplant patients, and persons with
metastatic tumors who are
receiving chemotherapy) with diverticulitis are at particular
risk.77 There is no evidence that the incidence of diverticulitis is higher in
this population than in the general population, but it is clear that
immunocompromised patients have
higher rates of operation once diverticulitis develops and
that their postoperative mortality is higher.78 Corticosteroid
intake causes a number of significant problems, such as
thinning of the colonic wall, lessening of the physical findings with
diverticulitis, and an attenuated inflammatory
response

41. • Any immunocompromised patient with abdominal pain
should be evaluated aggressively. Contrast-enhanced CT is
the imaging study of choice. The risk of perforation is
increased in this setting, as is the risk of postoperative
complications such as wound dehiscence. For an immunocompromised
patient who has recovered from an episode of
symptomatic diverticulitis, elective surgical treatment is recommended. A
renal transplant patient with asymptomatic
diverticulosis, however, need not undergo prophylactic colectomy.
Pretransplantation colonic screening of patients older
than 50 years does not reliably predict posttransplantation
colonic complications.

42. • atypical presentations
Diverticulitis may give rise to various unusual manifestations involving
multiple organ systems [see Table 1]. Not
surprisingly, immunocompromised patients are at particular risk.
Retroperitoneal abscesses can track into anatomic planes
(e.g., along the psoas muscle) or through the obturator foramen to areas
such as the neck, the thigh, the knee, the groin,
and the genitalia. CT scanning is essential to outline the
extent of such abscesses. Contrast enemas show the diverticula along with
a sinus tract into the abscess cavity. Cultures
of the abscess demonstrate the presence of colonic organisms

43. • such as Bacteroides fragilis. Definitive treatment consists of
wide abscess drainage and colon resection. Without aggressive surgical
management, mortality is high.
The protean manifestations of diverticulitis also include
pylephlebitis (which causes liver abscesses), arthritis, and
skin changes. Diverticulitis has, in fact, replaced appendicitis as the most
common source of liver abscesses of portal
origin. Simple abscesses may be drained percutaneously if
they are not too large, and multiple loculated abscesses may
be managed with open drainage. The main risk factors for
mortality from liver abscesses are immunosuppression,
underlying malignancy, the presence of multiple organisms,
and liver dysfunction. If the decision is made to perform a
colectomy, the procedure may be done after drainage of the
liver abscess or simultaneously with drainage during an
open procedure

45. • giant diverticula
An anatomic curiosity sometimes encountered in patients
with diverticular disease is a giant diverticulum, also termed
a giant gas cyst or a pneumocyst of the colon.80 These lesions,
which may reach diameters of 40 cm, are believed to develop
as a consequence of a ball-valve mechanism created by intermittent occlusion
of the neck by fecal material that traps air
in the diverticulum. Most giant diverticula are minimally
symptomatic, causing only mild abdominal pain, and perforation is rare. A
mobile mass may be palpable, and the gas-filled
cyst can be seen on plain abdominal films. As many as two
thirds of giant diverticula are opacified during a barium
enema and can thereby be differentiated from other abnormalities (e.g., a
mesenteric cyst, emphysematous cholecystitis, or a colon duplication) [see
Figure 18]. The cyst tends to
adhere densely to adjacent structures (e.g., the bladder and
the small bowel). The treatment of choice is resection of the
colon and the cyst; performing diverticulectomy alone can
lead to the development of a colocutaneous fistula

46. • recurrent diverticulitis after resection
Recurrent diverticulitis is rare after a colectomy for diverticulitis, occurring in
1 to 10% of patients.81 As many as 3%
of patients who have undergone resection for diverticulitis
will require repeat resection. The differential diagnosis
includes Crohn disease, irritable bowel syndrome, carcinoma,
and ischemic colitis. CT and colonoscopy should be carried
out. Particular care should be taken to review pathologic
specimens for evidence of Crohn disease.
The only significant determinant of recurrent diverticulitis is
the level of the anastomosis; the high pressure in the sigmoid
colon distal to the anastomosis appears to be responsible
• In one study, the risk of recurrence was four times greater in
patients with a colosigmoid anastomosis than in those with a
colorectal anastomosis.82 Reoperation requires a dissection that
commences in noninflamed tissue. Dissection may be particularly difficult
near the pelvic sidewall because of fibrosis; ureteral stenting may facilitate
identification of the ureters

47. • subacute and atypical diverticulitis
A small number of patients experience recurrent episodes
of left lower quadrant abdominal pain that are not accompanied by the classic findings
of acute diverticulitis (e.g., fever
and leukocytosis). The inflammatory changes associated with
diverticula in this subgroup have been referred to as atypical,
subacute, or smoldering diverticulitis.83,84 In this setting,
there is not always a direct association between endoscopic
and clinical findings; endoscopic evidence of diverticular
inflammation has been seen in asymptomatic patients.85 It
has been suggested that there is a relation between diverticular disease and colitis.86
Patients with chronic lower abdominal pain should undergo imaging studies and
endoscopic
evaluation, and other disorders (e.g., irritable bowel syndrome, inflammatory bowel
disease, drug-induced symptoms, and bowel ischemia) should be excluded. In most
cases
of atypical diverticulitis, endoscopic findings are normal.84 In
carefully selected patients, colectomy often eliminates the
abdominal pain, and many of these patients are eventually
found to have histologic signs of acute and chronic mucosal
inflammation