Diverticular
disease
2.
Acquired. The wall of the diverticulum lacks a proper muscular coat. Most
alimentary diverticula are thought to be acquired.
Most of these diverticula arise from the
mesenteric side of the bowel probably as the result of mucosal herniation
through the point of entry of blood vessels.
Duodenal diverticulum
2. Secondary. Diverticula of the duodenal cap resulting from long-standing
duodenal ulceration (Fig. 57.11).
A
Meckel’s diverticulum possesses all three coats of the intestinal wall and has
its own blood supply. It is therefore vulnerable to infection and obstruction in
the same way as the appendix. In 20 per cent of cases the mucosa contains
heterotopic epithelium, namely, gastric, colonic or sometimes pancreatic tissue.
When present, the abnormal mucosa lines the greater part of the proximal end of
the pouch and extends sometimes for a short distance into the nearby ileum.
Although Meckel’s diverticulum occurs with equal frequency in both sexes, symptoms usually resulting from the epithelium contained in the diverticulum predominantly occur in males. In order of frequency,
these symptoms are as
follows.
1.
Severe haemorrhage, caused by peptic ulceration. The blood is passed per
rectum, and is maroon in colour. Although the patient may vomit, the vomit does
not contain blood. There is rarely any pain and sometimes the bleeding precedes
perforation. An operation is required for serious progressive gastrointestinal
bleeding. When no lesion in the stomach or duodenum can be found the terminal
150 cm of ileum should be carefully inspected.
2.
Intussusception. In most cases, the apex of the intussusception is the
swollen, inflamed, heterotopic epithelium at the mouth of the divertictilum.
3. Meckel’s diverticulitis, with or without perforation, may result from
obstruction by food residue. The symptoms are those of acute appendicitis and,
unless the appendix has already been removed, the diagnosis is impossible before
operation. When a diverticulum perforates the symptoms may simulate those of a
perforated duodenal ulcer. Whether or not the diverticulum is perforated urgent
surgery is required. In nonperforated cases an inflamed diverticulum should be
sought as soon as it has been demonstrated that the appendix and Fallopian tubes
are not at fault.
4. Chronic peptic ulceration. As the
diverticulum is part of the midgut,
the pain, although related to meals, is felt around the umbilicus.
5. Intestinal obstruction. The presence of a hand between the apex of the
diverticulum and the umbilicus may cause obstruction either by the band itself
or by a volvulus around it.
Radiology
Meckel’s diverticulum can he very difficult
to demonstrate by contrast radiology; small bowel enema would he the most
accurate investigation.
In cases of repeated gastrointestinal
haemorrhage of unknown cause where a Meckel’s diverticulum is suspected the
abdomen is imaged with gamma camera after the injection of 30—100 mic Ci
(111—370 x 1010 Bq) of 99”Tc-labelled pertechnetate
intravenously. This may localise heterotopic gastric mucosa revealing the site
of a Meckel’s diverticulum in 90 per cent of cases.
‘Silent’
Meckel’s diverticulum
An aphorism attributed to Dr Charles Mayo is:
‘a Meckel’s diverticulum is frequently suspected, often sought for and
seldom found’. A Meckel’s diverticulum usually remains symptomless
throughout life and is found only at necropsy. When a silent Meckel’s
diverticulum is encountered in the course of an abdominal operation, provided it
is wide-mouthed and the wall of the diverticulum does not feel thickened, it can
he left. Where there is doubt and it can he removed without appreciable
additional risk it should he resected.
Exceptionally
a Meckel’s diverticulum is found in an inguinal or a femoral hernia sac —
Littre’s hernia.
Meckel’s
diverticulectomy
A Meckel’s diverticulum which is broad based
should not he amputated at its base and invaginated in the same way as a
vermiform appendix, because of the risk of stricture. Furthermore this does not
remove heterotopic epithelium where it is present. The steps of diverticulectomy
are shown in Fig. 57.15. Alternatively, a linear stapler device maybe used.
Where there is induration of the base of the diverticulum extending into the
adjacent ileum, it is advisable to resect a short segment of ileum containing
the diverticulum, restoring continuity with an end-to-end anastomosis.
Colon
Diverticula of the colon are acquired
herniations of colonic mucosa, protruding through the circular muscle at the
points where the blood vessels penetrate the colonic wall. They tend to occur in
rows between the strips of longitudinal muscle, sometimes partly covered by
appendices epiploicae. The condition is most commonly found in the sigmoid
colon but the caecum can also be involved and on occasion the entire large bowel
can be affected. The rectum with its complete muscle layers is not affected. In
90 per cent of cases the sigmoid colon is involved and is almost always the site
of inflammation, i.e. diverticulitis. Some 5
per cent of patients have associated gallstones and hiatus hernia (Saint’s
triad).
Diverticular
disease is rare in Africans and Asians who eat a diet that contains natural
fibre. In Western countries, where
Diverticulosis
It is important to distinguish between
diverticulosis and the presence of diverticula which may be asymptomatic, and
clinical diverticular disease where the diverticula are causing symptoms.
Diverticula probably arise as a result of muscular inco ordination and spasm,
resulting in increased segmentation and intraluminal pressures. Excessive
segmentation in response to food, prostigmine and morphine is found in colonic
motility studies, and this exaggerated response is more apparent in symptomatic
than in asymptomatic individuals. On histological investigation the
diverticulum consists of a protrusion of mucous membranes covered with
peritoneum.
There is thickening of the circular muscle fibres of the taeniae and the
intestine develops a concertina or sawtooth appearance on barium enema (Fig.
57.16). The diverticula occur between the muscle clefts making the mucosal
surface appear trabeculated. The elastin content of the taenia coli is increased
compared with controls.
Diverticulitis
Diverticulitis is the result of inflammation
of one or more diverticula, usually with some pericolitis. Episodes of diverticulitis
may be followed by years free of
symptoms, but the condition is essentially progressive — the longer the
duration the worse the symptoms and the greater the risk of complications.
Diverticulitis is not a precancerous condition, but cancer may coexist.
The
complications are the following:
1.
recurrent periodic inflammation and pain — in some
patients these
episodes may be clinically silent;
2. perforation leading to
general peritonitis or local
(pericolic) abscess
formation;
3. intestinal obstruction:
(a) in the sigmoid as a
result of progressive fibrosis causing stenosis,
(b)
in the small intestine caused by adherent loops of small
intestine on the pericolitis;
4. haemorrhage:
diverticulitis may present with profuse
colonic haemorrhage in
17 per cent of cases, often
requiring blood
transfusions;
5. fistula
formation (vesicocolic, vaginocolic, enterocolic,
colocutaneous) occurs in
5 per cent of cases, vesicolic
being the most common.
Diverticulitis.
Persistent lower abdominal pain, usually in the left iliac fossa with or without
peritonitis in patients of either sex over the age of 40, could be caused by
diverticulitis. Fever, malaise and leucocytosis can differentiate diverticulitis
from painful diverticulosis. The patient may pass loose stools or may be
constipated; the lower abdomen is tender especially on the left but occasionally
also in the right iliac fossa if the sigmoid loop lies across the midline. The
sigmoid colon is often palpable, tender and thickened. Rectal examination may
but does not usually reveal a tender mass. The condition has been likened to
left-sided appendicitis. Any urinary symptoms may herald the formation of a
vesicocolic fistula which leads to pneumaturia (flatus in the urine) and even
faeces in the urine.
Diagnosis
Sigmoidoscopy.
The mucosa may be normal and in acute attacks the sigmoidoscopy will be painful
and the mucosa inflamed. Colonoscopy or flexible sigmoidoscopy is more helpful (Fig.
57.18). The necks of diverticula can be seen and the narrowed area of
diverticulitis can be entered, but on occasion not passed because of the
severity of disease. The differential diagnosis from a carcinoma can be
impossible if a tight stenosis prevents endoscopy.
Diverticulosis should be treated with a
high-residue diet containing roughage in the form of wholemeal bread, flour,
fruit and vegetables. Bulk formers such as bran, Celevac, Isogel and Fybogel may
be given until the stools are soft. Painful diverticular disease may require bed
rest and antispasmodics.
Acute
diverticulitis is treated by bed rest and intravenous antibiotics (usually
cefuroxime and metronidazole). After the acute attack has subsided and if the
diagnosis has not already been confirmed by CT, a barium enema should be carried
out.
Operative
procedures for diverticular disease. Some 10 per cent of patients require an
operation either for recurrent attacks which make life a misery or for the
complications of diverticulitis.
2.
If there is obstruction, inflammatory oedema and adhesions or the bowel
is loaded with faeces, a Hartmann’s operation is the procedure of choice. The
involved area is resected. The rectum is closed at the penitoneal reflection,
and the left colon brought out as a left iliac fossa colostomy. The once
popular staged procedures using a preliminary transverse colostomy are now
rarely used except by inexperienced surgeons because of the high mortality
associated with them. In selected obstructed cases the bowel can be cleaned by
on-table lavage, placing a urinary
3.
In acute perforation, peritonitis soon becomes general and may be
purulent, which has a mortality rate of about 15 per cent. Gross faecal
peritonitis carries more than a 50 per cent mortality rate and pneumoperitoneum
is usually present; the diagnosis may not be confirmed until emergency
laparotomy. There is a choice of procedures:
(a) primary resection
and Hartmann’s procedure (see above);
(b) primary resection
and anastomosis after on-table lavage in selected cases;
(c) exteriorisation of
the affected bowel which is then opened as a colostomy, now rarely used;
(d)
suture of the perforation with drainage with or without proximal
defunction. In selected cases with a small leak and minimal soiling.
4. Fistulae can only be cured by resection of the diseased bowel and closure
of the fistula. In the case of a colovesical fistula it is usually possible to
‘pinch off’ the affected bowel
5. Haemorrhage from diverticulitis must be distinguished from
angiodysplasia. It usually responds to conservative management and occasionally
requires resection. On-table lavage and colonoscopy may be necessary to localise
the bleeding site.
Diverticular
disease and carcinoma coexist in 12 per cent of cases. Exploration may be
necessary but, even then, differentiation may be difficult until histological
investigations are available (Table 57.1). Weight loss, falling haemoglobin and
persistently positive occult blood are sinister features.
Solitary
diverticulum of the caecum and ascending colon is rare and is congenital, and
may present with symptoms and signs identical to those of acute appendicitis.
Extensive
diverticular disease can sometimes affect the right colon. This, however, is
rare in the West hut more common in Eastern countries. In Japan, China, Malaysia
and Korea, right-sided disease is twice as common as left-sided disease.