Page 168 - Medicine and Surgery

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164 Chapter 4: Gastrointestinal system

Sex face. There is then necrosis within the wall and a site of
No sex predisposition. perforation may be seen.

Geography Investigations
Disease of Western civilisations. There are no diagnostic tests. FBC may show a raised
white cell count, CRP may be raised. Ultrasound is in-
Aetiology/pathophysiology creasingly being used but does not exclude the diagnosis.
Acute appendicitis typically commences with colicky CT of the abdomen or laparoscopy may be indicated if
pain suggesting that obstruction of the lumen may be another diagnosis is suspected. In women of childbear-
afactor, e.g. by lymphoid hyperplasia, faecoliths, adhe- ing age a pregnancy test should be performed to exclude
sions, fibrosis or neoplasia. The pain is initially felt in the an ectopic pregnancy.
periumbilical region due to the pattern of visceral inner-
vation, but becomes localised to the right iliac fossa as Management
the parietal peritoneum becomes inflamed. Accumula- Conservative treatment has little place, except in patients
tion of secretions result in distension, mucosal necrosis unfit for surgery. Fluid resuscitation may be required
and invasion of the wall by commensal bacteria. Inflam- prior to surgery and intravenous antibiotics are com-
mationandimpairmentofbloodsupplyleadtogangrene menced.
and perforation. Once perforation has occurred there is Under general anaesthetic the abdomen is opened
migration of the bacteria into the peritoneum (peritoni- by an incision along the skin crease passing through
tis).Theoutcomedependsontheabilityoftheomentum McBurney’s point (one third of the distance from a
and surrounding organs to contain the infection. line drawn from the anterior superior iliac spine to
the umbilicus). The muscle fibres in each muscle layer
Clinical features are then split in the line of their fibres (grid iron in-
This is a classic cause of an acute abdomen. Pain is ini- cision). The mesoappendix is divided with ligation of
tially periumbilical, then migrates to the right iliac fossa. the appendicular artery. The appendix is ligated at its
There is mild to moderate fever, nausea and anorexia. base and removed. The stump is invaginated with a
Vomiting is uncommon. The presentation may be less purse string suture. Peritoneal washout is performed
specific in the young, pregnant and elderly. Develop- if there is pus in the abdomen. The wound is then
ment of the disease may be over hours to days partly closed in layers.
depending on host resistance. If there is an appendix abscess this should be surgically
Once there is peritonitis, the patient will have severe drained.
pain,exacerbatedbymovementandhasarigidabdomen Discovery of a normal appendix means other pathol-
with tenderness and guarding over the right iliac fossa. ogy must be excluded (i.e. convert the operation to a
A mass may be felt through the abdominal wall or rec- diagnostic laparotomy). In most cases, the appendix is
tally particularly if the omentum is wrapped around the removed to avoid confusion if patients ever re-present
appendix, or an abscess has formed. with an acute abdomen.

Macroscopy Prognosis
The appendix appears swollen and the surface vascula- Uncomplicated appendicitis has an overall mortality of
ture is yellow. There is a rough, yellow, fibrinous exudate 0.1%. Mortality rates may be as high as 5% following
on the surface. perforation.

Microscopy Meckel’s diverticulum
Initially there is acute inflammation of the mucosa,
which undergoes ulceration. There may be pus in the Definition
lumen. As the condition progresses the inflammation An ileal diverticulum occurring as a result of persistence
spreads through the wall until it reaches the serosal sur- of part of the vitellointestinal duct.