Appendicitis and Peritonitis
The appendix
• a normal true diverticulum of the cecum that is prone to
acute and chronic inflammation
• Acute appendicitis is most common in adolescents and
young adults, but may occur in any age group
• The lifetime risk for appendicitis is 7%; males are
affected slightly more often than females
• Despite the prevalence of acute appendicitis, the
diagnosis can be difficult to confirm preoperatively and
may be confused with mesenteric lymphadenitis, acute
salpingitis, ectopic pregnancy, mittelschmerz and Meckel
diverticulitis
Appendicitis: Pathogenesis
• luminal obstruction, usually caused by a small stone-like
mass of stool, or fecalith, or, less commonly, enlarged
lymph node during infection, a gallstone, tumour, or
mass of worms
• Luminal obstruction  Progressive increases in
intraluminal pressure compromise venous outflow 
ischemic injury
• Ischemic injury + stasis of luminal contents
 bacterial proliferation  inflammatory
responses including tissue oedema and
neutrophilic infiltration of the lumen, muscular
wall, and periappendiceal soft tissues
Appendicitis: Morphology
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In early acute appendicitis subserosal vessels are congested and there is a
modest perivascular neutrophilic infiltrate within all layers of the wall
The inflammatory reaction transforms the normal glistening serosa into a
dull, granular, erythematous surface
Diagnosis of acute appendicitis requires neutrophilic infiltration of the
muscularis propria. Although mucosal neutrophils and focal superficial
ulceration are often present, these are not specific markers of acute
appendicitis.
In severe cases a prominent neutrophilic exudate  serosal fibrinopurulent
reaction
 focal abscesses may form within the wall (acute suppurative appendicitis)
 further appendiceal compromise areas of hemorrhagic ulceration and
gangrenous necrosis that extends to the serosa (acute gangrenous
appendicitis), which is often followed by rupture and suppurative peritonitis.
Appendicitis: Clinical Features
CLASSIC Clinical Features
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Vague, often colicky, periumbilical pain (or epigastric) that ultimately localizes to the right lower quadrant (occurs
in only 66% of patients. However, in a male patient these symptoms are sufficient to advise surgical exploration.) \
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Within 12 hours, pain shifts to right lower quadrant, with steady ache worsened by walking or coughing
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nausea, vomiting, low-grade fever, and a mildly elevated peripheral white cell count
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A classic physical finding is McBurney's sign, deep tenderness located two thirds of the distance from the
umbilicus to the right anterior superior iliac spine (McBurney's point)
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Localized tenderness with guarding in the right lower quadrant
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Rebound tenderness
COMPLICATIONS
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appendiceal perforation
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If the process evolves slowly, adjacent organs such as the terminal ileum, cecum, and omentum may wall off the
appendiceal area so that a localized abscess will develop
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rupture of primary appendiceal abscesses may produce fistulas between the appendix and bladder, small
intestine, sigmoid, or cecum
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peritonitis
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Pyelophlebitis (Septic thrombophlebitis (pylephlebitis) of the portal venous system
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portal venous thrombosis
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liver abscess
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bacteremia
NOTE:
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recurrent acute appendicitis does occur, often with complete resolution of inflammation and symptoms between
attacks
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Recurrent acute appendicitis may also occur if a long appendiceal stump is left after initial appendectomy.
Tumors of the Appendix
• The most common tumour of the appendix is the carcinoid. It is
usually discovered incidentally. Although intramural and transmural
extension may be evident, nodal metastases are very infrequent,
and distant spread is exceptionally rare
• Conventional adenomas or non-mucin-producing adenocarcinomas
also occur in the appendix and may cause obstruction and
enlargement that mimics acute appendicitis
• Mucocele, a dilated appendix filled with mucin, may simply
represent an obstructed appendix containing inspissated mucin or
be a consequence of mucinous cystadenoma or mucinous
cystadenocarcinoma
• With cystadenocarcinoma, invasion through the appendiceal wall
can lead to intraperitoneal seeding and spread. In the most
advanced cases the abdomen fills with mucus and fibrosis , a
condition called pseudomyxoma peritoneii
Peritonitis
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Inflammation of the serosal membrane that lines the abdominal cavity
and the organs contained therein
Bacterial peritonitis
• occurs when bacteria from the gastrointestinal lumen are released
into the abdominal cavity, typically following perforation.
• occurs most commonly as a complication of acute appendicitis,
peptic ulcer, cholecystitis, diverticulitis, and intestinal ischemia.
Acute salpingitis, abdominal trauma, and peritoneal dialysis are
other potential sources of contaminating bacteria.
• E. coli, streptococci, S. aureus, enterococci, and C. perfringens are
implicated most often but virtually any bacteria can be associated
with bacterial peritonitis.
Clinical Presentation: Peritonitis
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Acute peritonitis is most often infectious and is usually related to a perforated viscus
(and called secondary peritonitis). When no intraabdominal source is identified,
infectious peritonitis is called primary or spontaneous.
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The cardinal manifestations of peritonitis are
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acute abdominal pain and tenderness, usually with fever
The location of the pain depends on the underlying cause and whether the inflammation is
localized or generalized.
Rigidity of the abdominal wall is common in both localized and generalized peritonitis.
Bowel sounds are usually absent.
Tachycardia, hypotension, and signs of dehydration are common.
Leukocytosis and marked acidosis are common laboratory findings.
Plain abdominal films may show dilation of large and small bowel with oedema of the bowel
wall. Free air under the diaphragm is associated with a perforated viscus. CT and/or
ultrasonography can identify the presence of free fluid or an abscess. When ascites is
present, diagnostic paracentesis with cell count (>250 neutrophils/ L is usual in peritonitis),
protein and lactate dehydrogenase levels, and culture is essential. In elderly and
immunosuppressed patients, signs of peritoneal irritation may be more difficult to detect.
Peritoneum: Tumours
• Most tumors of the peritoneum are malignant and can be divided into
primary and secondary forms.
• Primary tumors arising from peritoneal lining are mesotheliomas that
are similar to tumors of the pleura and pericardium. Peritoneal
mesotheliomas are almost always associated with significant asbestos
exposure. It has been hypothesized that swallowed asbestos fibers
somehow penetrate through the intestinal wall to reach the
peritoneum.
• Secondary tumors of the peritoneum are quite common. In any form of
advanced cancer, direct spread to the serosal surface or metastatic
seeding (peritoneal carcinomatosis) may occur. The most common
tumors producing diffuse serosal implants are ovarian and pancreatic
adenocarcinoma. Appendiceal mucinous carcinomas may
produce pseudomyxoma peritoneii. However, any intra-abdominal
malignancy, as well as a wide variety of tumors of extra-abdominal
origin, may spread to the peritoneum.
• Robbin’s
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